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The evolutionary history of a phylogenetically distinct group of organisms (a clade) can be traced by using a phylogenetic tree. Such phylogenetic trees can also be used to measure the amount of evolutionary history captured by each member species (node) in the tree. Evolutionary Distinctness (ED) and Evolutionary Distinct and Globally Endangered Score (EDGE) are two such vital parameters that could elucidate the phylogenetic history captured in member species. Birds evolved from a lineage led by dinosaurs over a period of ~100 million years and today the class Aves is a highly specious lineage with over 10,000 extant species. About 5% of the global avian diversity is represented in Sri Lanka with 34 endemic species. Here we quantify the evolutionary distinctness of Sri Lankan avifauna using a phylo-genetic tree constructed for all the 342 bird species that are found in 71 Important Bird Areas (IBAs) of Sri Lanka. We constructed the tree from DNA sequence archives at www.birdtree.org using bioinformatics tools and higher-order phylogenetic backbones. ED and EDGE scores of all 342 birds were calculated in R Package. Batrachostomus moniliger (Ceylon Frogmouth) is the most evolutionary distinct (ED) species in Sri Lanka, while Otus thilohoffmanni (Serendib Scops-owl) is the most evolutionary distinct endangered lineage (EDGE) of the country. Harpactes fasciatus (Malabar Trogon), Pitta brachyura (Indian Pitta), Phoenicopterus roseus (Greater Flamingo) and Tachybaptus ruficollis (Little Grebe) are the rest of the top 5 species with highest ED. Centropus chlororhynchus (Green-billed Coucal), Myophonus blighi (Ceylon Whistling-thrush), Leptoptilos javanicus (Lesser Adjutant) and Pelecanus philippensis (Spot-billed Pelican) are the rest of the highest EDGE species in Sri Lanka. Members of order Charadriiformes (shorebirds, terns and gulls) in general have the lowest ED values. The species that have evolved recently and have sister or closely related species have relatively low ED. A species that has a high EDGE score is an isolated node in the phylogenetic tree and a globally threatened species. We believe that these parameters will give a novel evolutionary perspective for both wildlife managers and birders on avifauna of Sri Lanka.
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WILDLANKA Vol.5, No.1, pp. 001 - 010, 2017.
Copyright 2017 Department of Wildlife Conservation, Sri Lanka.
EVOLUTIONARY DISTINCTIVENESS OF
SRI LANKAN AVIFAUNA
D.K. ABEYRAMA and S.S. SENEVIRATNE*
Avian Evolution Node, Department of Zoology and Environment Sciences, Faculty of Science,
University of Colombo, Colombo 03, Sri Lanka
*sam@sci.cmb.ac.lk
ABSTRACT - The evolutionary history of a phylogenetically distinct group of organisms (a
clade) can be traced by using a phylogenetic tree. Such phylogenetic trees can also be used to
measure the amount of evolutionary history captured by each member species (node) in the
tree. Evolutionary Distinctness (ED) and Evolutionary Distinct and Globally Endangered
Score (EDGE) are two such vital parameters that could elucidate the phylogenetic history
captured in member species. Birds evolved from a lineage led by dinosaurs over a period of
~100 million years and today the class Aves is a highly specious lineage with over 10,000 extant
species. About 5% of the global avian diversity is represented in Sri Lanka with 34 endemic
species. Here we quantify the evolutionary distinctness of Sri Lankan avifauna using a phylo-
genetic tree constructed for all the 342 bird species that are found in 71 Important Bird Areas
(IBAs) of Sri Lanka. We constructed the tree from DNA sequence archives at
www.birdtree.org using bioinformatics tools and higher-order phylogenetic backbones. ED
and EDGE scores of all 342 birds were calculated in R Package. Batrachostomus moniliger
(Ceylon Frogmouth) is the most evolutionary distinct (ED) species in Sri Lanka, while Otus
thilohoffmanni (Serendib Scops-owl) is the most evolutionary distinct endangered lineage
(EDGE) of the country. Harpactes fasciatus (Malabar Trogon), Pitta brachyura (Indian Pitta),
Phoenicopterus roseus (Greater Flamingo) and Tachybaptus ruficollis (Little Grebe) are the
rest of the top 5 species with highest ED. Centropus chlororhynchus (Green-billed Coucal),
Myophonus blighi (Ceylon Whistling-thrush), Leptoptilos javanicus (Lesser Adjutant) and
Pelecanus philippensis (Spot-billed Pelican) are the rest of the highest EDGE species in Sri
Lanka. Members of order Charadriiformes (shorebirds, terns and gulls) in general have the
lowest ED values. The species that have evolved recently and have sister or closely related
species have relatively low ED. A species that has a high EDGE score is an isolated node in the
phylogenetic tree and a globally threatened species. We believe that these parameters will give
a novel evolutionary perspective for both wildlife managers and birders on avifauna of Sri
Lanka.
KEY WORDS : avifauna, birds, evolutionary distinctness, evolutionary distinct and globally endan-
gered Score, Phylogeny, Sri Lanka
INTRODUCTION
Birds have evolved from a lineage led by
dinosaurs over a period of ~100 million years
(Brusatte et al., 2015). The explosive radiation
in this lineage however had been taken place in
~50 MYA, which made them highly diverged
with about 10,000 extant species (Jetz et al.,
2012). Of that about 500 species of birds, 5% of
the global avian diversity, is represented in Sri
Lanka (Rasmussen & Anderton, 2005). Sri
Lanka is a continental island in the Indian
Ocean which is periodically connected with the
mainland India throughout its geological history
(MacArthur & Wilson, 1967). As a result the
avifauna of the island is widely considered as a
subset of Indian Avifauna (Ripley et al., 1949;
Bossuyt et al., 2004). However Sri Lanka
carries a unique avifaunal diversity through
accommodating 34 endemic bird species
(Fernando et al., 2016, Rasmussen & Anderton,
2005). The endemicity birds in Sri Lanka
(7.43%) is highest in the region. About 240
resident species, 220 winter migrants and 40
pelagic seabirds comprise the rest of the bird
diversity of the Island (National Red List of Sri
Lanka, 2012). Does each of these 500 species of
birds found in Sri Lanka carry a similar
evolutionary significance in representing 100
million years of their evolutionary history?
The evolutionary history of a
phylogenetically distinct group of organisms
(clade) can be traced using a phylogenetic tree,
in which the tips and nodes of the tree stand for
descendant taxa and their common ancestors
respectively (Vellend et al., 2007). Nee and
May, (1997) suggested that the more distal
nodes (i.e. species) that a branch carries, the
lower the amount of evolutionary history
captured by each of its distal nodes in that
particular branch (Fig. 01). Based on this
principle several phylogenetic parameters are
being developed in the recent past to measure
how much evolutionary history is captured by a
single species (Box 01). Evolutionary
Distinctness (ED), and Evolutionary Distinct
and Globally Endangered Score (EDGE score)
are two of such key parameters that can be used
to quantify the amount of phylogenetic history
captured by the given entity (Jetz et al., 2014).
In this paper the evolutionary distinctness of
Sri Lankan avifauna is quantified using a
phylogenetic tree constructed for all the 342
bird species that are found in 71 Important Bird
Areas (IBAs; www.birdlife.org/worldwide/
programmes/sites-ibas) of Sri Lanka. We
constructed the tree from DNA sequence
archives in global genetic databases
(www.birdtree.org) using bioinformatics tools
and higher-order phylogenetic backbones
(Hackett et al., 2008).
MATERIALS AND METHODS
Total species list, which contains all
recorded species in 71 IBAs was obtained from
the IBA database of the Field Ornithology
Group of Sri Lanka. The list was fed into the
option ‘Phylogeny subsets’ of ‘www.birdtree.
org’ and a set of 5000 phylogenetic trees was
generated. ‘Hackett All Species: a set of 10000
trees with 9993 OTUs each’, which refers to the
database of species in the study by Hackett et al.
(2008) that contains 10,000 trees each with
9,993 operational units was selected as the
source of trees.
To generate the grand tree for all 342
species recorded, we followed four main steps.
For the construction of the tree we combined
relaxed clock molecular trees of well supported
clades with a backbone which contained
representatives from each clade (Jetz et al.,
2012). As the first step each species was
assigned to one of the 158 clades which arise
from the 158 tips of the backbone trees. Then
relaxed-clock trees were constructed for each
clade. The species that do not have genetic
information were plugged in to their relevant
clades using the information obtained by
combining the relaxed clock trees and available
taxonomic information (Jetz et al., 2012). The
final tree was constructed by merging trees from
either of the previous two steps with time
calibrated relaxed molecular clock backbone
trees (Jetz et al., 2012; www.birdtree.org).
A consensus tree (Fig. 02) was generated
from the file of 5000 phylogenetic trees
generated by www.birdtree.org using
‘TreeAnnotator v1.8.2’ of the software BEAST
(BEAST v1.8.2). First 100 trees were discarded
as ‘burnin trees’. ‘User target tree’ was selected
as the target tree type while ‘Median heights’
was selected as the node heights. Posterior
probability for the tree was 0.75 (Drummond et
al., 2007). R platform (R Development Core
Team) was used to measure the Evolutionary
Distinctiveness (ED) and EDGE scores for each
species.
The consensus tree was generated using
‘Treeannotator’ and saved in .tre format. Using
the R codes below, the ED of all 342 species
were calculated.
To calculate the Evolutionary Distinctiveness
Originality<-evol.distinc
(tree,type="fair.proportion")
We used EDGE = ln(1+ED) + GE * ln(2), to
calculate the EDGE scores for each species in
the list (Isaac et al.,2007).
Where,
ED= Evolutionary Distinctiveness
GE= Red list category weight
(Least Concern=0, Near Threatened and
Conservation Dependent=1, Vulnerable=2,
Endangered=3, Critically Endangered=4)
We ranked all 342 species based on their ED
and EDGE values.
The global ED and EDGE scores of birds
were taken from Jetz et al. (2014).
RESULTS
According to our calculations the Ceylon
Frogmouth (B. moniliger), Malabar Trogon (H.
fasciatus), Indian Pitta (P. brachyura), Greater
Flamingo (P. roseus), Little Grebe (T.
ruficollis), Spot-billed Pelican (Pelecanus
philippensis), Eurasian Hoopoe (Upupa epops),
Osprey (Pandion haliaetus), Black-winged Kite
(Elanus caeruleus) and Oriental Bay-owl
(Phodilus badius) are the ten most evolutionary
distinct (ED) species of birds found in Sri Lanka
(Table 01, Fig. 03).
The ten most evolutionary distinct
endangered species (EDGE) of the country are
Serendib Scops-owl (O. thilohoffmanni),
Green-billed Coucal (C. chlororhynchus),
Ceylon Whistling-thrush (M. blighi), Lesser
Adjutant (L. javanicus), Spot-billed Pelican (P.
philippensis), Ceylon Blue Magpie (Urocissa
ornata), Red-faced Malkoha (Phaenicophaeus
pyrrhocephalus), Malabar Pied Hornbill
(Anthracoceros coronatus), Ceylon
Wood-pigeon (Columba torringtoniae) and
Black-headed Ibis (Threskiornis
melanocephalus) (Table 02, Fig 04).
Seabirds belong to Fig 04 the order
Charedriiformes such as the Roseate Tern
(Sterna dougallii), Common Tern (Sterna
hirundo), Sandwich Tern (Sterna
sandvicensis), Lesser Crested Tern (Sterna
bengalensis) and Great Crested Tern (Sterna
bergii) have the lowest evolutionary
significance and EDGE scores among Sri
Lankan birds.
DISCUSSION
Not all species carry the same evolutionary
significance because the members from
different clades of the tree of life have different
levels of phylogenetic isolation (Brusatte et al.,
2015). In birds, members of the order
Passeriformes have relatively low evolutionary
distinctiveness than that of some members of
non-passerine clades (Jetz et al., 2014). The
species with high evolutionary distinctiveness
(ED) mostly underwent relatively older
speciation events where the ones with low ED
have recent divergent history (Hackett et al.,
2008). Furthermore, species with lower ED
have diverged recently and are not isolated in
the tree of life as they have numerous close
relatives near its distal node (Redding et al.,
2008). Species that have higher ED are isolated
in the phylogenetic tree that is mainly due to
extinction of the member species. According to
the phylogenetic relationships of birds in Sri
Lanka (Fig. 02), it is clear that Ceylon
Frogmouth is isolated in the phylogenetic tree
and has speciated long ago. As a result Ceylon
Frogmouth has the greatest evolutionary
significance (75.2995) among Sri Lankan birds.
It is noteworthy that no endemic species is listed
as the top 10 species with highest ED (Table
01). The reason may be that these endemic
species have diverged recently and still they
have sister or closely related species in Sri
Lanka (Rasmussen & Anderton, 2005; Ripley &
Beehler, 1990). For example, Zosterops
ceylonensis (Highland White-eye) which is an
endemic species has Zosterops palpebrosus
(Oriental White-eye) as its sister species. The
ED of these two species are the same and is
relatively low (11.9007). Among the 34
endemic bird species of Sri Lanka (Table 03),
Ocyceros gingalensis (Ceylon Grey Hornbill)
has the highest ED (49.0085), followed by
Green-billed Coucal, Loriculus beryllinus
(Ceylon Lorikeet), Glaucidium castanonotum
(Chestnut-backed Owlet) and Galloperdix
bicalcarata (Ceylon Spurfowl). Among
endemics Sturnus albofrontatus (White-faced
Starling) has the lowest ED (11.7064) followed
by Chrysocolaptes stricklandi (Layard’s
Flameback), Gracula ptilogenys (Ceylon
Hill-myna), Turdoides rufescens (Ceylon Rufus
Babbler) and Highland White-eye.
The order of ranking is different between
the global ranking of ED and the Sri Lankan
ranking of ED. For example, Indian Pitta, which
ranks 3rd in the local ranking, is 10th when these
10 species are arranged according to their
global rankings. Osprey in the other hand ranks
8th in the local list, is 1st when it is taken in the
order of global rankings. The reason for this is
in the local context, Indian Pitta is a monotypic
genus, so its ED goes up when only the birds of
Sri Lanka are considered, but when consider the
global phylogeny, there are 30 species of pittas
(Fig. 02). In the case of Osprey, it is a
monotypic genus in both local (Fig. 02) and
global contexts. So the ED of Osprey is high
locally and globally. As described previously,
the EDGE score of a species depends on both
the ED and the IUCN red list status of that
species (Isaac et al., 2007). Therefore, to have a
high EDGE score, the species should be an
isolated node in the phylogenetic tree with a
globally threatened status. Our results showed
that the Serendib Scops-owl has the highest
EDGE score (5.26). Serendib Scops-owl
however has a relatively low ED (23.00) but it is
an endangered endemic. Ceylon Frogmouth
topped the list for highest ED, but it is 13th
species in the EDGE list. Six species out of the
10 top ranked evolutionary distinct endangered
lineages, are endemic to Sri Lanka (Table 03).
However the ED of all these endemic species
are relatively low.
The order of ranking is again different when
considering the National Red List and Global
Red List for the calculations of EDGE score.
The Serendib Scops-owl which is 1st when
using Global Red List is the 23rd when using
National Red List, while Slaty-legged Crake
(Rallina eurizonoides) is 66th when using
Global Red List but is 1st when National Red
List is used. We stick to Global IUCN rankings
because the National Red List tend to
overemphasise several small populations of
globally widespread species such as
Slaty-legged Crake, Yellow-legged Green
Pigeon (Treron phoenicopterus) and Indian
Courser (Cursorius coromandelicus), all of
them are Critically Endangered in the Local
IUCN list due to small population size. On the
other hand, some of the range restricted Sri
Lankan endemics are lower in the National Red
List’s vulnerability index even though they are
range-restricted endangered species in the
IUCN Global list.
The evolutionary past of a clade can be
traced through phylogenetic trees. Such
phylogenetic trees can also be used to measure
the amount of evolutionary history captured by
its member species. Evolutionary Distinctness
(ED) and Evolutionary Distinct and Globally
Endangered Score (EDGE) are two such vital
parameters that could elucidate the
phylogenetic history captured in member
species. Using the total species recorded in
IBAs of Sri Lanka we constructed a
phylogenetic tree to evaluate the ED and EDGE
scores of Sri Lankan Birds. Ceylon Frogmouth
is the most evolutionary distinct (ED) species in
the island, while Serendib Scops-owl is the
most evolutionary distinct endangered lineage
(EDGE). Members of order Charadriiformes in
general have the lowest ED values.
ACKNOWLEDGEMENT
We are grateful to Dr. Praveen Karanth and
the members of the Evolving Phylo - Lab at the
Indian Institute of Science and Dr. Arne Mooers
at the Simon Fraser University, Canada for
assistance with the phylogenetic tools. The
Field Ornithology Group of Sri Lanka provided
the IBA database for this study. Department of
Zoology and Environment Sciences, University
of Colombo provided funding for DA and SS
for this study. We also thank Mr. Hasitha Perera
and Dr. Gehan Rajeev for providing bird images
and Dr. Nishanthi Perera and Dr. Hashendra
Kathriarrachchi for commenting on the manu-
script.
INTRODUCTION
Birds have evolved from a lineage led by
dinosaurs over a period of ~100 million years
(Brusatte et al., 2015). The explosive radiation
in this lineage however had been taken place in
~50 MYA, which made them highly diverged
with about 10,000 extant species (Jetz et al.,
2012). Of that about 500 species of birds, 5% of
the global avian diversity, is represented in Sri
Lanka (Rasmussen & Anderton, 2005). Sri
Lanka is a continental island in the Indian
Ocean which is periodically connected with the
mainland India throughout its geological history
(MacArthur & Wilson, 1967). As a result the
002May, 2017]
avifauna of the island is widely considered as a
subset of Indian Avifauna (Ripley et al., 1949;
Bossuyt et al., 2004). However Sri Lanka
carries a unique avifaunal diversity through
accommodating 34 endemic bird species
(Fernando et al., 2016, Rasmussen & Anderton,
2005). The endemicity birds in Sri Lanka
(7.43%) is highest in the region. About 240
resident species, 220 winter migrants and 40
pelagic seabirds comprise the rest of the bird
diversity of the Island (National Red List of Sri
Lanka, 2012). Does each of these 500 species of
birds found in Sri Lanka carry a similar
evolutionary significance in representing 100
million years of their evolutionary history?
The evolutionary history of a
phylogenetically distinct group of organisms
(clade) can be traced using a phylogenetic tree,
in which the tips and nodes of the tree stand for
descendant taxa and their common ancestors
respectively (Vellend et al., 2007). Nee and
May, (1997) suggested that the more distal
nodes (i.e. species) that a branch carries, the
lower the amount of evolutionary history
captured by each of its distal nodes in that
particular branch (Fig. 01). Based on this
principle several phylogenetic parameters are
being developed in the recent past to measure
how much evolutionary history is captured by a
single species (Box 01). Evolutionary
Distinctness (ED), and Evolutionary Distinct
and Globally Endangered Score (EDGE score)
are two of such key parameters that can be used
to quantify the amount of phylogenetic history
captured by the given entity (Jetz et al., 2014).
EVOLUTIONARY DISTINCTIVENESS OF SRI LANKAN AVIFAUNA
In this paper the evolutionary distinctness of
Sri Lankan avifauna is quantified using a
phylogenetic tree constructed for all the 342
bird species that are found in 71 Important Bird
Areas (IBAs; www.birdlife.org/worldwide/
programmes/sites-ibas) of Sri Lanka. We
constructed the tree from DNA sequence
archives in global genetic databases
(www.birdtree.org) using bioinformatics tools
and higher-order phylogenetic backbones
(Hackett et al., 2008).
MATERIALS AND METHODS
Total species list, which contains all
recorded species in 71 IBAs was obtained from
the IBA database of the Field Ornithology
Group of Sri Lanka. The list was fed into the
option ‘Phylogeny subsets’ of ‘www.birdtree.
org’ and a set of 5000 phylogenetic trees was
generated. ‘Hackett All Species: a set of 10000
trees with 9993 OTUs each’, which refers to the
database of species in the study by Hackett et al.
(2008) that contains 10,000 trees each with
9,993 operational units was selected as the
source of trees.
To generate the grand tree for all 342
species recorded, we followed four main steps.
For the construction of the tree we combined
relaxed clock molecular trees of well supported
clades with a backbone which contained
representatives from each clade (Jetz et al.,
2012). As the first step each species was
assigned to one of the 158 clades which arise
from the 158 tips of the backbone trees. Then
relaxed-clock trees were constructed for each
clade. The species that do not have genetic
information were plugged in to their relevant
clades using the information obtained by
combining the relaxed clock trees and available
taxonomic information (Jetz et al., 2012). The
final tree was constructed by merging trees from
either of the previous two steps with time
calibrated relaxed molecular clock backbone
trees (Jetz et al., 2012; www.birdtree.org).
A consensus tree (Fig. 02) was generated
from the file of 5000 phylogenetic trees
generated by www.birdtree.org using
‘TreeAnnotator v1.8.2’ of the software BEAST
(BEAST v1.8.2). First 100 trees were discarded
as ‘burnin trees’. ‘User target tree’ was selected
as the target tree type while ‘Median heights’
was selected as the node heights. Posterior
probability for the tree was 0.75 (Drummond et
al., 2007). R platform (R Development Core
Team) was used to measure the Evolutionary
Distinctiveness (ED) and EDGE scores for each
species.
The consensus tree was generated using
‘Treeannotator’ and saved in .tre format. Using
the R codes below, the ED of all 342 species
were calculated.
To calculate the Evolutionary Distinctiveness
Originality<-evol.distinc
(tree,type="fair.proportion")
We used EDGE = ln(1+ED) + GE * ln(2), to
calculate the EDGE scores for each species in
the list (Isaac et al.,2007).
Where,
ED= Evolutionary Distinctiveness
GE= Red list category weight
(Least Concern=0, Near Threatened and
Conservation Dependent=1, Vulnerable=2,
Endangered=3, Critically Endangered=4)
We ranked all 342 species based on their ED
and EDGE values.
The global ED and EDGE scores of birds
were taken from Jetz et al. (2014).
RESULTS
According to our calculations the Ceylon
Frogmouth (B. moniliger), Malabar Trogon (H.
fasciatus), Indian Pitta (P. brachyura), Greater
Flamingo (P. roseus), Little Grebe (T.
ruficollis), Spot-billed Pelican (Pelecanus
philippensis), Eurasian Hoopoe (Upupa epops),
Osprey (Pandion haliaetus), Black-winged Kite
(Elanus caeruleus) and Oriental Bay-owl
(Phodilus badius) are the ten most evolutionary
distinct (ED) species of birds found in Sri Lanka
(Table 01, Fig. 03).
Evolutionary Distinctness (ED) is a measure of isolation (of species) in the phylogenetic tree.
Higher the Evolutionary Distinctness of a species, lower the number of closely related species
it has in the phylogenetic tree (Jetz et al., 2014). ED score for a species is calculated by
assigning a value to each branch (which is equal to branch length), dividing it by the number of
species diverge from the branch and taking the summation of values for all the branches in its
evolutionary path from the root of phylogeny to the present (Fig 01; Isaac et al., 2007).
Evolutionary Distinct and Globally Endangered (EDGE) Score is an index derived from
combining ED scores with the IUCN red list categories (Butchart et al., 2010). It is a measure
of the evolutionary distinctness of endangered lineages.
BOX 1: Two parameters used to quantify the amount of evolutionary history captured by a member
species (node) in a phylogenetic tree.
The ten most evolutionary distinct
endangered species (EDGE) of the country are
Serendib Scops-owl (O. thilohoffmanni),
Green-billed Coucal (C. chlororhynchus),
Ceylon Whistling-thrush (M. blighi), Lesser
Adjutant (L. javanicus), Spot-billed Pelican (P.
philippensis), Ceylon Blue Magpie (Urocissa
ornata), Red-faced Malkoha (Phaenicophaeus
pyrrhocephalus), Malabar Pied Hornbill
(Anthracoceros coronatus), Ceylon
Wood-pigeon (Columba torringtoniae) and
Black-headed Ibis (Threskiornis
melanocephalus) (Table 02, Fig 04).
Seabirds belong to Fig 04 the order
Charedriiformes such as the Roseate Tern
(Sterna dougallii), Common Tern (Sterna
hirundo), Sandwich Tern (Sterna
sandvicensis), Lesser Crested Tern (Sterna
bengalensis) and Great Crested Tern (Sterna
bergii) have the lowest evolutionary
significance and EDGE scores among Sri
Lankan birds.
DISCUSSION
Not all species carry the same evolutionary
significance because the members from
different clades of the tree of life have different
levels of phylogenetic isolation (Brusatte et al.,
2015). In birds, members of the order
Passeriformes have relatively low evolutionary
distinctiveness than that of some members of
non-passerine clades (Jetz et al., 2014). The
species with high evolutionary distinctiveness
(ED) mostly underwent relatively older
speciation events where the ones with low ED
have recent divergent history (Hackett et al.,
2008). Furthermore, species with lower ED
have diverged recently and are not isolated in
the tree of life as they have numerous close
relatives near its distal node (Redding et al.,
2008). Species that have higher ED are isolated
in the phylogenetic tree that is mainly due to
extinction of the member species. According to
the phylogenetic relationships of birds in Sri
Lanka (Fig. 02), it is clear that Ceylon
Frogmouth is isolated in the phylogenetic tree
and has speciated long ago. As a result Ceylon
Frogmouth has the greatest evolutionary
significance (75.2995) among Sri Lankan birds.
It is noteworthy that no endemic species is listed
as the top 10 species with highest ED (Table
01). The reason may be that these endemic
species have diverged recently and still they
have sister or closely related species in Sri
Lanka (Rasmussen & Anderton, 2005; Ripley &
Beehler, 1990). For example, Zosterops
ceylonensis (Highland White-eye) which is an
endemic species has Zosterops palpebrosus
(Oriental White-eye) as its sister species. The
ED of these two species are the same and is
relatively low (11.9007). Among the 34
endemic bird species of Sri Lanka (Table 03),
Ocyceros gingalensis (Ceylon Grey Hornbill)
has the highest ED (49.0085), followed by
Green-billed Coucal, Loriculus beryllinus
(Ceylon Lorikeet), Glaucidium castanonotum
(Chestnut-backed Owlet) and Galloperdix
bicalcarata (Ceylon Spurfowl). Among
endemics Sturnus albofrontatus (White-faced
Starling) has the lowest ED (11.7064) followed
by Chrysocolaptes stricklandi (Layard’s
Flameback), Gracula ptilogenys (Ceylon
Hill-myna), Turdoides rufescens (Ceylon Rufus
Babbler) and Highland White-eye.
The order of ranking is different between
the global ranking of ED and the Sri Lankan
ranking of ED. For example, Indian Pitta, which
ranks 3rd in the local ranking, is 10th when these
10 species are arranged according to their
global rankings. Osprey in the other hand ranks
8th in the local list, is 1st when it is taken in the
order of global rankings. The reason for this is
in the local context, Indian Pitta is a monotypic
genus, so its ED goes up when only the birds of
Sri Lanka are considered, but when consider the
global phylogeny, there are 30 species of pittas
(Fig. 02). In the case of Osprey, it is a
monotypic genus in both local (Fig. 02) and
global contexts. So the ED of Osprey is high
locally and globally. As described previously,
the EDGE score of a species depends on both
the ED and the IUCN red list status of that
species (Isaac et al., 2007). Therefore, to have a
high EDGE score, the species should be an
isolated node in the phylogenetic tree with a
globally threatened status. Our results showed
that the Serendib Scops-owl has the highest
EDGE score (5.26). Serendib Scops-owl
however has a relatively low ED (23.00) but it is
an endangered endemic. Ceylon Frogmouth
topped the list for highest ED, but it is 13th
species in the EDGE list. Six species out of the
10 top ranked evolutionary distinct endangered
lineages, are endemic to Sri Lanka (Table 03).
However the ED of all these endemic species
are relatively low.
The order of ranking is again different when
considering the National Red List and Global
Red List for the calculations of EDGE score.
The Serendib Scops-owl which is 1st when
using Global Red List is the 23rd when using
National Red List, while Slaty-legged Crake
(Rallina eurizonoides) is 66th when using
Global Red List but is 1st when National Red
List is used. We stick to Global IUCN rankings
because the National Red List tend to
overemphasise several small populations of
globally widespread species such as
Slaty-legged Crake, Yellow-legged Green
Pigeon (Treron phoenicopterus) and Indian
Courser (Cursorius coromandelicus), all of
them are Critically Endangered in the Local
IUCN list due to small population size. On the
other hand, some of the range restricted Sri
Lankan endemics are lower in the National Red
List’s vulnerability index even though they are
range-restricted endangered species in the
IUCN Global list.
The evolutionary past of a clade can be
traced through phylogenetic trees. Such
phylogenetic trees can also be used to measure
the amount of evolutionary history captured by
its member species. Evolutionary Distinctness
(ED) and Evolutionary Distinct and Globally
Endangered Score (EDGE) are two such vital
parameters that could elucidate the
phylogenetic history captured in member
species. Using the total species recorded in
IBAs of Sri Lanka we constructed a
phylogenetic tree to evaluate the ED and EDGE
scores of Sri Lankan Birds. Ceylon Frogmouth
is the most evolutionary distinct (ED) species in
the island, while Serendib Scops-owl is the
most evolutionary distinct endangered lineage
(EDGE). Members of order Charadriiformes in
general have the lowest ED values.
ACKNOWLEDGEMENT
We are grateful to Dr. Praveen Karanth and
the members of the Evolving Phylo - Lab at the
Indian Institute of Science and Dr. Arne Mooers
at the Simon Fraser University, Canada for
assistance with the phylogenetic tools. The
Field Ornithology Group of Sri Lanka provided
the IBA database for this study. Department of
Zoology and Environment Sciences, University
of Colombo provided funding for DA and SS
for this study. We also thank Mr. Hasitha Perera
and Dr. Gehan Rajeev for providing bird images
and Dr. Nishanthi Perera and Dr. Hashendra
Kathriarrachchi for commenting on the manu-
script.
INTRODUCTION
Birds have evolved from a lineage led by
dinosaurs over a period of ~100 million years
(Brusatte et al., 2015). The explosive radiation
in this lineage however had been taken place in
~50 MYA, which made them highly diverged
with about 10,000 extant species (Jetz et al.,
2012). Of that about 500 species of birds, 5% of
the global avian diversity, is represented in Sri
Lanka (Rasmussen & Anderton, 2005). Sri
Lanka is a continental island in the Indian
Ocean which is periodically connected with the
mainland India throughout its geological history
(MacArthur & Wilson, 1967). As a result the
avifauna of the island is widely considered as a
subset of Indian Avifauna (Ripley et al., 1949;
Bossuyt et al., 2004). However Sri Lanka
carries a unique avifaunal diversity through
accommodating 34 endemic bird species
(Fernando et al., 2016, Rasmussen & Anderton,
2005). The endemicity birds in Sri Lanka
(7.43%) is highest in the region. About 240
resident species, 220 winter migrants and 40
pelagic seabirds comprise the rest of the bird
diversity of the Island (National Red List of Sri
Lanka, 2012). Does each of these 500 species of
birds found in Sri Lanka carry a similar
evolutionary significance in representing 100
million years of their evolutionary history?
The evolutionary history of a
phylogenetically distinct group of organisms
(clade) can be traced using a phylogenetic tree,
in which the tips and nodes of the tree stand for
descendant taxa and their common ancestors
respectively (Vellend et al., 2007). Nee and
May, (1997) suggested that the more distal
nodes (i.e. species) that a branch carries, the
lower the amount of evolutionary history
captured by each of its distal nodes in that
particular branch (Fig. 01). Based on this
principle several phylogenetic parameters are
being developed in the recent past to measure
how much evolutionary history is captured by a
single species (Box 01). Evolutionary
Distinctness (ED), and Evolutionary Distinct
and Globally Endangered Score (EDGE score)
are two of such key parameters that can be used
to quantify the amount of phylogenetic history
captured by the given entity (Jetz et al., 2014).
WILDLANKA [Vol. 5, No. 1003
In this paper the evolutionary distinctness of
Sri Lankan avifauna is quantified using a
phylogenetic tree constructed for all the 342
bird species that are found in 71 Important Bird
Areas (IBAs; www.birdlife.org/worldwide/
programmes/sites-ibas) of Sri Lanka. We
constructed the tree from DNA sequence
archives in global genetic databases
(www.birdtree.org) using bioinformatics tools
and higher-order phylogenetic backbones
(Hackett et al., 2008).
MATERIALS AND METHODS
Total species list, which contains all
recorded species in 71 IBAs was obtained from
the IBA database of the Field Ornithology
Group of Sri Lanka. The list was fed into the
option ‘Phylogeny subsets’ of ‘www.birdtree.
org’ and a set of 5000 phylogenetic trees was
generated. ‘Hackett All Species: a set of 10000
trees with 9993 OTUs each’, which refers to the
database of species in the study by Hackett et al.
(2008) that contains 10,000 trees each with
9,993 operational units was selected as the
source of trees.
To generate the grand tree for all 342
species recorded, we followed four main steps.
For the construction of the tree we combined
relaxed clock molecular trees of well supported
clades with a backbone which contained
representatives from each clade (Jetz et al.,
2012). As the first step each species was
assigned to one of the 158 clades which arise
from the 158 tips of the backbone trees. Then
relaxed-clock trees were constructed for each
clade. The species that do not have genetic
information were plugged in to their relevant
clades using the information obtained by
combining the relaxed clock trees and available
taxonomic information (Jetz et al., 2012). The
final tree was constructed by merging trees from
either of the previous two steps with time
calibrated relaxed molecular clock backbone
trees (Jetz et al., 2012; www.birdtree.org).
A consensus tree (Fig. 02) was generated
from the file of 5000 phylogenetic trees
generated by www.birdtree.org using
‘TreeAnnotator v1.8.2’ of the software BEAST
(BEAST v1.8.2). First 100 trees were discarded
as ‘burnin trees’. ‘User target tree’ was selected
as the target tree type while ‘Median heights’
was selected as the node heights. Posterior
probability for the tree was 0.75 (Drummond et
al., 2007). R platform (R Development Core
Team) was used to measure the Evolutionary
Distinctiveness (ED) and EDGE scores for each
species.
The consensus tree was generated using
‘Treeannotator’ and saved in .tre format. Using
the R codes below, the ED of all 342 species
were calculated.
To calculate the Evolutionary Distinctiveness
Originality<-evol.distinc
(tree,type="fair.proportion")
We used EDGE = ln(1+ED) + GE * ln(2), to
calculate the EDGE scores for each species in
the list (Isaac et al.,2007).
Where,
ED= Evolutionary Distinctiveness
GE= Red list category weight
(Least Concern=0, Near Threatened and
Conservation Dependent=1, Vulnerable=2,
Endangered=3, Critically Endangered=4)
We ranked all 342 species based on their ED
and EDGE values.
The global ED and EDGE scores of birds
were taken from Jetz et al. (2014).
RESULTS
According to our calculations the Ceylon
Frogmouth (B. moniliger), Malabar Trogon (H.
fasciatus), Indian Pitta (P. brachyura), Greater
Flamingo (P. roseus), Little Grebe (T.
ruficollis), Spot-billed Pelican (Pelecanus
philippensis), Eurasian Hoopoe (Upupa epops),
Osprey (Pandion haliaetus), Black-winged Kite
(Elanus caeruleus) and Oriental Bay-owl
(Phodilus badius) are the ten most evolutionary
distinct (ED) species of birds found in Sri Lanka
(Table 01, Fig. 03).
FIGURE 1: Basic procedure for calculating ED
for 7 hypothetical species. Numbers above the
branches are the branch lengths and numbers
below are the number of descendent taxa.
MYBP means millions of years before present
(Isaac et al., 2007).
FIGURE 2: Phylogenetic tree of total 342 bird species reported in IBAs of Sri Lanka.
The ten most evolutionary distinct
endangered species (EDGE) of the country are
Serendib Scops-owl (O. thilohoffmanni),
Green-billed Coucal (C. chlororhynchus),
Ceylon Whistling-thrush (M. blighi), Lesser
Adjutant (L. javanicus), Spot-billed Pelican (P.
philippensis), Ceylon Blue Magpie (Urocissa
ornata), Red-faced Malkoha (Phaenicophaeus
pyrrhocephalus), Malabar Pied Hornbill
(Anthracoceros coronatus), Ceylon
Wood-pigeon (Columba torringtoniae) and
Black-headed Ibis (Threskiornis
melanocephalus) (Table 02, Fig 04).
Seabirds belong to Fig 04 the order
Charedriiformes such as the Roseate Tern
(Sterna dougallii), Common Tern (Sterna
hirundo), Sandwich Tern (Sterna
sandvicensis), Lesser Crested Tern (Sterna
bengalensis) and Great Crested Tern (Sterna
bergii) have the lowest evolutionary
significance and EDGE scores among Sri
Lankan birds.
DISCUSSION
Not all species carry the same evolutionary
significance because the members from
different clades of the tree of life have different
levels of phylogenetic isolation (Brusatte et al.,
2015). In birds, members of the order
Passeriformes have relatively low evolutionary
distinctiveness than that of some members of
non-passerine clades (Jetz et al., 2014). The
species with high evolutionary distinctiveness
(ED) mostly underwent relatively older
speciation events where the ones with low ED
have recent divergent history (Hackett et al.,
2008). Furthermore, species with lower ED
have diverged recently and are not isolated in
the tree of life as they have numerous close
relatives near its distal node (Redding et al.,
2008). Species that have higher ED are isolated
in the phylogenetic tree that is mainly due to
extinction of the member species. According to
the phylogenetic relationships of birds in Sri
Lanka (Fig. 02), it is clear that Ceylon
Frogmouth is isolated in the phylogenetic tree
and has speciated long ago. As a result Ceylon
Frogmouth has the greatest evolutionary
significance (75.2995) among Sri Lankan birds.
It is noteworthy that no endemic species is listed
as the top 10 species with highest ED (Table
01). The reason may be that these endemic
species have diverged recently and still they
have sister or closely related species in Sri
Lanka (Rasmussen & Anderton, 2005; Ripley &
Beehler, 1990). For example, Zosterops
ceylonensis (Highland White-eye) which is an
endemic species has Zosterops palpebrosus
(Oriental White-eye) as its sister species. The
ED of these two species are the same and is
relatively low (11.9007). Among the 34
endemic bird species of Sri Lanka (Table 03),
Ocyceros gingalensis (Ceylon Grey Hornbill)
has the highest ED (49.0085), followed by
Green-billed Coucal, Loriculus beryllinus
(Ceylon Lorikeet), Glaucidium castanonotum
(Chestnut-backed Owlet) and Galloperdix
bicalcarata (Ceylon Spurfowl). Among
endemics Sturnus albofrontatus (White-faced
Starling) has the lowest ED (11.7064) followed
by Chrysocolaptes stricklandi (Layard’s
Flameback), Gracula ptilogenys (Ceylon
Hill-myna), Turdoides rufescens (Ceylon Rufus
Babbler) and Highland White-eye.
The order of ranking is different between
the global ranking of ED and the Sri Lankan
ranking of ED. For example, Indian Pitta, which
ranks 3rd in the local ranking, is 10th when these
10 species are arranged according to their
global rankings. Osprey in the other hand ranks
8th in the local list, is 1st when it is taken in the
order of global rankings. The reason for this is
in the local context, Indian Pitta is a monotypic
genus, so its ED goes up when only the birds of
Sri Lanka are considered, but when consider the
global phylogeny, there are 30 species of pittas
(Fig. 02). In the case of Osprey, it is a
monotypic genus in both local (Fig. 02) and
global contexts. So the ED of Osprey is high
locally and globally. As described previously,
the EDGE score of a species depends on both
the ED and the IUCN red list status of that
species (Isaac et al., 2007). Therefore, to have a
high EDGE score, the species should be an
isolated node in the phylogenetic tree with a
globally threatened status. Our results showed
that the Serendib Scops-owl has the highest
EDGE score (5.26). Serendib Scops-owl
however has a relatively low ED (23.00) but it is
an endangered endemic. Ceylon Frogmouth
topped the list for highest ED, but it is 13th
species in the EDGE list. Six species out of the
10 top ranked evolutionary distinct endangered
lineages, are endemic to Sri Lanka (Table 03).
However the ED of all these endemic species
are relatively low.
The order of ranking is again different when
considering the National Red List and Global
Red List for the calculations of EDGE score.
The Serendib Scops-owl which is 1st when
using Global Red List is the 23rd when using
National Red List, while Slaty-legged Crake
(Rallina eurizonoides) is 66th when using
Global Red List but is 1st when National Red
List is used. We stick to Global IUCN rankings
because the National Red List tend to
overemphasise several small populations of
globally widespread species such as
Slaty-legged Crake, Yellow-legged Green
Pigeon (Treron phoenicopterus) and Indian
Courser (Cursorius coromandelicus), all of
them are Critically Endangered in the Local
IUCN list due to small population size. On the
other hand, some of the range restricted Sri
Lankan endemics are lower in the National Red
List’s vulnerability index even though they are
range-restricted endangered species in the
IUCN Global list.
The evolutionary past of a clade can be
traced through phylogenetic trees. Such
phylogenetic trees can also be used to measure
the amount of evolutionary history captured by
its member species. Evolutionary Distinctness
(ED) and Evolutionary Distinct and Globally
Endangered Score (EDGE) are two such vital
parameters that could elucidate the
phylogenetic history captured in member
species. Using the total species recorded in
IBAs of Sri Lanka we constructed a
phylogenetic tree to evaluate the ED and EDGE
scores of Sri Lankan Birds. Ceylon Frogmouth
is the most evolutionary distinct (ED) species in
the island, while Serendib Scops-owl is the
most evolutionary distinct endangered lineage
(EDGE). Members of order Charadriiformes in
general have the lowest ED values.
ACKNOWLEDGEMENT
We are grateful to Dr. Praveen Karanth and
the members of the Evolving Phylo - Lab at the
Indian Institute of Science and Dr. Arne Mooers
at the Simon Fraser University, Canada for
assistance with the phylogenetic tools. The
Field Ornithology Group of Sri Lanka provided
the IBA database for this study. Department of
Zoology and Environment Sciences, University
of Colombo provided funding for DA and SS
for this study. We also thank Mr. Hasitha Perera
and Dr. Gehan Rajeev for providing bird images
and Dr. Nishanthi Perera and Dr. Hashendra
Kathriarrachchi for commenting on the manu-
script.
INTRODUCTION
Birds have evolved from a lineage led by
dinosaurs over a period of ~100 million years
(Brusatte et al., 2015). The explosive radiation
in this lineage however had been taken place in
~50 MYA, which made them highly diverged
with about 10,000 extant species (Jetz et al.,
2012). Of that about 500 species of birds, 5% of
the global avian diversity, is represented in Sri
Lanka (Rasmussen & Anderton, 2005). Sri
Lanka is a continental island in the Indian
Ocean which is periodically connected with the
mainland India throughout its geological history
(MacArthur & Wilson, 1967). As a result the
avifauna of the island is widely considered as a
subset of Indian Avifauna (Ripley et al., 1949;
Bossuyt et al., 2004). However Sri Lanka
carries a unique avifaunal diversity through
accommodating 34 endemic bird species
(Fernando et al., 2016, Rasmussen & Anderton,
2005). The endemicity birds in Sri Lanka
(7.43%) is highest in the region. About 240
resident species, 220 winter migrants and 40
pelagic seabirds comprise the rest of the bird
diversity of the Island (National Red List of Sri
Lanka, 2012). Does each of these 500 species of
birds found in Sri Lanka carry a similar
evolutionary significance in representing 100
million years of their evolutionary history?
The evolutionary history of a
phylogenetically distinct group of organisms
(clade) can be traced using a phylogenetic tree,
in which the tips and nodes of the tree stand for
descendant taxa and their common ancestors
respectively (Vellend et al., 2007). Nee and
May, (1997) suggested that the more distal
nodes (i.e. species) that a branch carries, the
lower the amount of evolutionary history
captured by each of its distal nodes in that
particular branch (Fig. 01). Based on this
principle several phylogenetic parameters are
being developed in the recent past to measure
how much evolutionary history is captured by a
single species (Box 01). Evolutionary
Distinctness (ED), and Evolutionary Distinct
and Globally Endangered Score (EDGE score)
are two of such key parameters that can be used
to quantify the amount of phylogenetic history
captured by the given entity (Jetz et al., 2014).
004May, 2017] EVOLUTIONARY DISTINCTIVENESS OF SRI LANKAN AVIFAUNA
In this paper the evolutionary distinctness of
Sri Lankan avifauna is quantified using a
phylogenetic tree constructed for all the 342
bird species that are found in 71 Important Bird
Areas (IBAs; www.birdlife.org/worldwide/
programmes/sites-ibas) of Sri Lanka. We
constructed the tree from DNA sequence
archives in global genetic databases
(www.birdtree.org) using bioinformatics tools
and higher-order phylogenetic backbones
(Hackett et al., 2008).
MATERIALS AND METHODS
Total species list, which contains all
recorded species in 71 IBAs was obtained from
the IBA database of the Field Ornithology
Group of Sri Lanka. The list was fed into the
option ‘Phylogeny subsets’ of ‘www.birdtree.
org’ and a set of 5000 phylogenetic trees was
generated. ‘Hackett All Species: a set of 10000
trees with 9993 OTUs each’, which refers to the
database of species in the study by Hackett et al.
(2008) that contains 10,000 trees each with
9,993 operational units was selected as the
source of trees.
To generate the grand tree for all 342
species recorded, we followed four main steps.
For the construction of the tree we combined
relaxed clock molecular trees of well supported
clades with a backbone which contained
representatives from each clade (Jetz et al.,
2012). As the first step each species was
assigned to one of the 158 clades which arise
from the 158 tips of the backbone trees. Then
relaxed-clock trees were constructed for each
clade. The species that do not have genetic
information were plugged in to their relevant
clades using the information obtained by
combining the relaxed clock trees and available
taxonomic information (Jetz et al., 2012). The
final tree was constructed by merging trees from
either of the previous two steps with time
calibrated relaxed molecular clock backbone
trees (Jetz et al., 2012; www.birdtree.org).
A consensus tree (Fig. 02) was generated
from the file of 5000 phylogenetic trees
generated by www.birdtree.org using
‘TreeAnnotator v1.8.2’ of the software BEAST
(BEAST v1.8.2). First 100 trees were discarded
as ‘burnin trees’. ‘User target tree’ was selected
as the target tree type while ‘Median heights’
was selected as the node heights. Posterior
probability for the tree was 0.75 (Drummond et
al., 2007). R platform (R Development Core
Team) was used to measure the Evolutionary
Distinctiveness (ED) and EDGE scores for each
species.
The consensus tree was generated using
‘Treeannotator’ and saved in .tre format. Using
the R codes below, the ED of all 342 species
were calculated.
To calculate the Evolutionary Distinctiveness
Originality<-evol.distinc
(tree,type="fair.proportion")
We used EDGE = ln(1+ED) + GE * ln(2), to
calculate the EDGE scores for each species in
the list (Isaac et al.,2007).
Where,
ED= Evolutionary Distinctiveness
GE= Red list category weight
(Least Concern=0, Near Threatened and
Conservation Dependent=1, Vulnerable=2,
Endangered=3, Critically Endangered=4)
We ranked all 342 species based on their ED
and EDGE values.
The global ED and EDGE scores of birds
were taken from Jetz et al. (2014).
RESULTS
According to our calculations the Ceylon
Frogmouth (B. moniliger), Malabar Trogon (H.
fasciatus), Indian Pitta (P. brachyura), Greater
Flamingo (P. roseus), Little Grebe (T.
ruficollis), Spot-billed Pelican (Pelecanus
philippensis), Eurasian Hoopoe (Upupa epops),
Osprey (Pandion haliaetus), Black-winged Kite
(Elanus caeruleus) and Oriental Bay-owl
(Phodilus badius) are the ten most evolutionary
distinct (ED) species of birds found in Sri Lanka
(Table 01, Fig. 03).
FIGURE 3: Some of the most evolutionary distinct (ED) species of birds in Sri Lanka: A. Ceylon
Frogmouth (B. moniliger), B. Malabar Trogon (H. fasciatus), C. Eurasian Hoopoe (U. epops), D.
Indian Pitta (P. brachyura), E. Little Grebe (T. ruficollis), and F. Greater Flamingo (P. roseus).
Photo credit: Hasitha Perera (images A - F).
The ten most evolutionary distinct
endangered species (EDGE) of the country are
Serendib Scops-owl (O. thilohoffmanni),
Green-billed Coucal (C. chlororhynchus),
Ceylon Whistling-thrush (M. blighi), Lesser
Adjutant (L. javanicus), Spot-billed Pelican (P.
philippensis), Ceylon Blue Magpie (Urocissa
ornata), Red-faced Malkoha (Phaenicophaeus
pyrrhocephalus), Malabar Pied Hornbill
(Anthracoceros coronatus), Ceylon
Wood-pigeon (Columba torringtoniae) and
Black-headed Ibis (Threskiornis
melanocephalus) (Table 02, Fig 04).
Seabirds belong to Fig 04 the order
Charedriiformes such as the Roseate Tern
(Sterna dougallii), Common Tern (Sterna
hirundo), Sandwich Tern (Sterna
sandvicensis), Lesser Crested Tern (Sterna
bengalensis) and Great Crested Tern (Sterna
bergii) have the lowest evolutionary
significance and EDGE scores among Sri
Lankan birds.
DISCUSSION
Not all species carry the same evolutionary
significance because the members from
different clades of the tree of life have different
levels of phylogenetic isolation (Brusatte et al.,
2015). In birds, members of the order
Passeriformes have relatively low evolutionary
distinctiveness than that of some members of
non-passerine clades (Jetz et al., 2014). The
species with high evolutionary distinctiveness
(ED) mostly underwent relatively older
speciation events where the ones with low ED
have recent divergent history (Hackett et al.,
2008). Furthermore, species with lower ED
have diverged recently and are not isolated in
the tree of life as they have numerous close
relatives near its distal node (Redding et al.,
2008). Species that have higher ED are isolated
in the phylogenetic tree that is mainly due to
extinction of the member species. According to
the phylogenetic relationships of birds in Sri
Lanka (Fig. 02), it is clear that Ceylon
Frogmouth is isolated in the phylogenetic tree
and has speciated long ago. As a result Ceylon
Frogmouth has the greatest evolutionary
significance (75.2995) among Sri Lankan birds.
It is noteworthy that no endemic species is listed
as the top 10 species with highest ED (Table
01). The reason may be that these endemic
species have diverged recently and still they
have sister or closely related species in Sri
Lanka (Rasmussen & Anderton, 2005; Ripley &
Beehler, 1990). For example, Zosterops
ceylonensis (Highland White-eye) which is an
endemic species has Zosterops palpebrosus
(Oriental White-eye) as its sister species. The
ED of these two species are the same and is
relatively low (11.9007). Among the 34
endemic bird species of Sri Lanka (Table 03),
Ocyceros gingalensis (Ceylon Grey Hornbill)
has the highest ED (49.0085), followed by
Green-billed Coucal, Loriculus beryllinus
(Ceylon Lorikeet), Glaucidium castanonotum
(Chestnut-backed Owlet) and Galloperdix
bicalcarata (Ceylon Spurfowl). Among
endemics Sturnus albofrontatus (White-faced
Starling) has the lowest ED (11.7064) followed
by Chrysocolaptes stricklandi (Layard’s
Flameback), Gracula ptilogenys (Ceylon
Hill-myna), Turdoides rufescens (Ceylon Rufus
Babbler) and Highland White-eye.
The order of ranking is different between
the global ranking of ED and the Sri Lankan
ranking of ED. For example, Indian Pitta, which
ranks 3rd in the local ranking, is 10th when these
10 species are arranged according to their
global rankings. Osprey in the other hand ranks
8th in the local list, is 1st when it is taken in the
order of global rankings. The reason for this is
in the local context, Indian Pitta is a monotypic
genus, so its ED goes up when only the birds of
Sri Lanka are considered, but when consider the
global phylogeny, there are 30 species of pittas
(Fig. 02). In the case of Osprey, it is a
monotypic genus in both local (Fig. 02) and
global contexts. So the ED of Osprey is high
locally and globally. As described previously,
the EDGE score of a species depends on both
the ED and the IUCN red list status of that
species (Isaac et al., 2007). Therefore, to have a
high EDGE score, the species should be an
isolated node in the phylogenetic tree with a
globally threatened status. Our results showed
that the Serendib Scops-owl has the highest
EDGE score (5.26). Serendib Scops-owl
however has a relatively low ED (23.00) but it is
an endangered endemic. Ceylon Frogmouth
topped the list for highest ED, but it is 13th
species in the EDGE list. Six species out of the
10 top ranked evolutionary distinct endangered
lineages, are endemic to Sri Lanka (Table 03).
However the ED of all these endemic species
are relatively low.
The order of ranking is again different when
considering the National Red List and Global
Red List for the calculations of EDGE score.
The Serendib Scops-owl which is 1st when
using Global Red List is the 23rd when using
National Red List, while Slaty-legged Crake
(Rallina eurizonoides) is 66th when using
Global Red List but is 1st when National Red
List is used. We stick to Global IUCN rankings
because the National Red List tend to
overemphasise several small populations of
globally widespread species such as
Slaty-legged Crake, Yellow-legged Green
Pigeon (Treron phoenicopterus) and Indian
Courser (Cursorius coromandelicus), all of
them are Critically Endangered in the Local
IUCN list due to small population size. On the
other hand, some of the range restricted Sri
Lankan endemics are lower in the National Red
List’s vulnerability index even though they are
range-restricted endangered species in the
IUCN Global list.
The evolutionary past of a clade can be
traced through phylogenetic trees. Such
phylogenetic trees can also be used to measure
the amount of evolutionary history captured by
its member species. Evolutionary Distinctness
(ED) and Evolutionary Distinct and Globally
Endangered Score (EDGE) are two such vital
parameters that could elucidate the
phylogenetic history captured in member
species. Using the total species recorded in
IBAs of Sri Lanka we constructed a
phylogenetic tree to evaluate the ED and EDGE
scores of Sri Lankan Birds. Ceylon Frogmouth
is the most evolutionary distinct (ED) species in
the island, while Serendib Scops-owl is the
most evolutionary distinct endangered lineage
(EDGE). Members of order Charadriiformes in
general have the lowest ED values.
ACKNOWLEDGEMENT
We are grateful to Dr. Praveen Karanth and
the members of the Evolving Phylo - Lab at the
Indian Institute of Science and Dr. Arne Mooers
at the Simon Fraser University, Canada for
assistance with the phylogenetic tools. The
Field Ornithology Group of Sri Lanka provided
the IBA database for this study. Department of
Zoology and Environment Sciences, University
of Colombo provided funding for DA and SS
for this study. We also thank Mr. Hasitha Perera
and Dr. Gehan Rajeev for providing bird images
and Dr. Nishanthi Perera and Dr. Hashendra
Kathriarrachchi for commenting on the manu-
script.
INTRODUCTION
Birds have evolved from a lineage led by
dinosaurs over a period of ~100 million years
(Brusatte et al., 2015). The explosive radiation
in this lineage however had been taken place in
~50 MYA, which made them highly diverged
with about 10,000 extant species (Jetz et al.,
2012). Of that about 500 species of birds, 5% of
the global avian diversity, is represented in Sri
Lanka (Rasmussen & Anderton, 2005). Sri
Lanka is a continental island in the Indian
Ocean which is periodically connected with the
mainland India throughout its geological history
(MacArthur & Wilson, 1967). As a result the
avifauna of the island is widely considered as a
subset of Indian Avifauna (Ripley et al., 1949;
Bossuyt et al., 2004). However Sri Lanka
carries a unique avifaunal diversity through
accommodating 34 endemic bird species
(Fernando et al., 2016, Rasmussen & Anderton,
2005). The endemicity birds in Sri Lanka
(7.43%) is highest in the region. About 240
resident species, 220 winter migrants and 40
pelagic seabirds comprise the rest of the bird
diversity of the Island (National Red List of Sri
Lanka, 2012). Does each of these 500 species of
birds found in Sri Lanka carry a similar
evolutionary significance in representing 100
million years of their evolutionary history?
The evolutionary history of a
phylogenetically distinct group of organisms
(clade) can be traced using a phylogenetic tree,
in which the tips and nodes of the tree stand for
descendant taxa and their common ancestors
respectively (Vellend et al., 2007). Nee and
May, (1997) suggested that the more distal
nodes (i.e. species) that a branch carries, the
lower the amount of evolutionary history
captured by each of its distal nodes in that
particular branch (Fig. 01). Based on this
principle several phylogenetic parameters are
being developed in the recent past to measure
how much evolutionary history is captured by a
single species (Box 01). Evolutionary
Distinctness (ED), and Evolutionary Distinct
and Globally Endangered Score (EDGE score)
are two of such key parameters that can be used
to quantify the amount of phylogenetic history
captured by the given entity (Jetz et al., 2014).
WILDLANKA [Vol. 5, No. 1005
In this paper the evolutionary distinctness of
Sri Lankan avifauna is quantified using a
phylogenetic tree constructed for all the 342
bird species that are found in 71 Important Bird
Areas (IBAs; www.birdlife.org/worldwide/
programmes/sites-ibas) of Sri Lanka. We
constructed the tree from DNA sequence
archives in global genetic databases
(www.birdtree.org) using bioinformatics tools
and higher-order phylogenetic backbones
(Hackett et al., 2008).
MATERIALS AND METHODS
Total species list, which contains all
recorded species in 71 IBAs was obtained from
the IBA database of the Field Ornithology
Group of Sri Lanka. The list was fed into the
option ‘Phylogeny subsets’ of ‘www.birdtree.
org’ and a set of 5000 phylogenetic trees was
generated. ‘Hackett All Species: a set of 10000
trees with 9993 OTUs each’, which refers to the
database of species in the study by Hackett et al.
(2008) that contains 10,000 trees each with
9,993 operational units was selected as the
source of trees.
To generate the grand tree for all 342
species recorded, we followed four main steps.
For the construction of the tree we combined
relaxed clock molecular trees of well supported
clades with a backbone which contained
representatives from each clade (Jetz et al.,
2012). As the first step each species was
assigned to one of the 158 clades which arise
from the 158 tips of the backbone trees. Then
relaxed-clock trees were constructed for each
clade. The species that do not have genetic
information were plugged in to their relevant
clades using the information obtained by
combining the relaxed clock trees and available
taxonomic information (Jetz et al., 2012). The
final tree was constructed by merging trees from
either of the previous two steps with time
calibrated relaxed molecular clock backbone
trees (Jetz et al., 2012; www.birdtree.org).
A consensus tree (Fig. 02) was generated
from the file of 5000 phylogenetic trees
generated by www.birdtree.org using
‘TreeAnnotator v1.8.2’ of the software BEAST
(BEAST v1.8.2). First 100 trees were discarded
as ‘burnin trees’. ‘User target tree’ was selected
as the target tree type while ‘Median heights’
was selected as the node heights. Posterior
probability for the tree was 0.75 (Drummond et
al., 2007). R platform (R Development Core
Team) was used to measure the Evolutionary
Distinctiveness (ED) and EDGE scores for each
species.
The consensus tree was generated using
‘Treeannotator’ and saved in .tre format. Using
the R codes below, the ED of all 342 species
were calculated.
To calculate the Evolutionary Distinctiveness
Originality<-evol.distinc
(tree,type="fair.proportion")
We used EDGE = ln(1+ED) + GE * ln(2), to
calculate the EDGE scores for each species in
the list (Isaac et al.,2007).
Where,
ED= Evolutionary Distinctiveness
GE= Red list category weight
(Least Concern=0, Near Threatened and
Conservation Dependent=1, Vulnerable=2,
Endangered=3, Critically Endangered=4)
We ranked all 342 species based on their ED
and EDGE values.
The global ED and EDGE scores of birds
were taken from Jetz et al. (2014).
RESULTS
According to our calculations the Ceylon
Frogmouth (B. moniliger), Malabar Trogon (H.
fasciatus), Indian Pitta (P. brachyura), Greater
Flamingo (P. roseus), Little Grebe (T.
ruficollis), Spot-billed Pelican (Pelecanus
philippensis), Eurasian Hoopoe (Upupa epops),
Osprey (Pandion haliaetus), Black-winged Kite
(Elanus caeruleus) and Oriental Bay-owl
(Phodilus badius) are the ten most evolutionary
distinct (ED) species of birds found in Sri Lanka
(Table 01, Fig. 03).
TABLE 1: Description of 10 bird species that have the highest evolutionary distinctiveness (ED) in
Sri Lanka
ED Scientific Name Common IUCN status Breeding
Local Global English Name Status
Rank Rank
01 281 Batrachostomus moniliger Ceylon Frogmouth Least Concern Breeding
resident
02 847 Harpactes fasciatus Malabar Trogon Least Concern Breeding
resident
03 1426 Pitta brachyura Indian Pitta Least Concern Winter
migrant
04 435 Phoenicopterus roseus Greater Flamingo Least Concern Winter
migrant and
summer
loiterer
05 320 Tachybaptus ruficollis Little Grebe Least Concern Breeding
resident
06 292 Pelecanus philippensis Spot-billed Pelican Near Breeding
Threatened resident
07 49 Upupa epops Eurasian Hoopoe Least Concern Breeding
resident
08 08 Pandion haliaetus Osprey Least Concern Rare migrant
09 726 Elanus caeruleus Black-winged Kite Least Concern Breeding
resident
10 109 Phodilus badius Oriental Bay-owl Least Concern Rare breeding
resident
The ten most evolutionary distinct
endangered species (EDGE) of the country are
Serendib Scops-owl (O. thilohoffmanni),
Green-billed Coucal (C. chlororhynchus),
Ceylon Whistling-thrush (M. blighi), Lesser
Adjutant (L. javanicus), Spot-billed Pelican (P.
philippensis), Ceylon Blue Magpie (Urocissa
ornata), Red-faced Malkoha (Phaenicophaeus
pyrrhocephalus), Malabar Pied Hornbill
(Anthracoceros coronatus), Ceylon
Wood-pigeon (Columba torringtoniae) and
Black-headed Ibis (Threskiornis
melanocephalus) (Table 02, Fig 04).
Seabirds belong to Fig 04 the order
Charedriiformes such as the Roseate Tern
(Sterna dougallii), Common Tern (Sterna
hirundo), Sandwich Tern (Sterna
sandvicensis), Lesser Crested Tern (Sterna
bengalensis) and Great Crested Tern (Sterna
bergii) have the lowest evolutionary
significance and EDGE scores among Sri
Lankan birds.
DISCUSSION
Not all species carry the same evolutionary
significance because the members from
different clades of the tree of life have different
levels of phylogenetic isolation (Brusatte et al.,
2015). In birds, members of the order
Passeriformes have relatively low evolutionary
distinctiveness than that of some members of
non-passerine clades (Jetz et al., 2014). The
species with high evolutionary distinctiveness
(ED) mostly underwent relatively older
speciation events where the ones with low ED
have recent divergent history (Hackett et al.,
2008). Furthermore, species with lower ED
have diverged recently and are not isolated in
the tree of life as they have numerous close
relatives near its distal node (Redding et al.,
2008). Species that have higher ED are isolated
in the phylogenetic tree that is mainly due to
extinction of the member species. According to
the phylogenetic relationships of birds in Sri
Lanka (Fig. 02), it is clear that Ceylon
Frogmouth is isolated in the phylogenetic tree
and has speciated long ago. As a result Ceylon
Frogmouth has the greatest evolutionary
significance (75.2995) among Sri Lankan birds.
It is noteworthy that no endemic species is listed
as the top 10 species with highest ED (Table
01). The reason may be that these endemic
species have diverged recently and still they
have sister or closely related species in Sri
Lanka (Rasmussen & Anderton, 2005; Ripley &
Beehler, 1990). For example, Zosterops
ceylonensis (Highland White-eye) which is an
endemic species has Zosterops palpebrosus
(Oriental White-eye) as its sister species. The
ED of these two species are the same and is
relatively low (11.9007). Among the 34
endemic bird species of Sri Lanka (Table 03),
Ocyceros gingalensis (Ceylon Grey Hornbill)
has the highest ED (49.0085), followed by
Green-billed Coucal, Loriculus beryllinus
(Ceylon Lorikeet), Glaucidium castanonotum
(Chestnut-backed Owlet) and Galloperdix
bicalcarata (Ceylon Spurfowl). Among
endemics Sturnus albofrontatus (White-faced
Starling) has the lowest ED (11.7064) followed
by Chrysocolaptes stricklandi (Layard’s
Flameback), Gracula ptilogenys (Ceylon
Hill-myna), Turdoides rufescens (Ceylon Rufus
Babbler) and Highland White-eye.
The order of ranking is different between
the global ranking of ED and the Sri Lankan
ranking of ED. For example, Indian Pitta, which
ranks 3rd in the local ranking, is 10th when these
10 species are arranged according to their
global rankings. Osprey in the other hand ranks
8th in the local list, is 1st when it is taken in the
order of global rankings. The reason for this is
in the local context, Indian Pitta is a monotypic
genus, so its ED goes up when only the birds of
Sri Lanka are considered, but when consider the
global phylogeny, there are 30 species of pittas
(Fig. 02). In the case of Osprey, it is a
monotypic genus in both local (Fig. 02) and
global contexts. So the ED of Osprey is high
locally and globally. As described previously,
the EDGE score of a species depends on both
the ED and the IUCN red list status of that
species (Isaac et al., 2007). Therefore, to have a
high EDGE score, the species should be an
isolated node in the phylogenetic tree with a
globally threatened status. Our results showed
that the Serendib Scops-owl has the highest
EDGE score (5.26). Serendib Scops-owl
however has a relatively low ED (23.00) but it is
an endangered endemic. Ceylon Frogmouth
topped the list for highest ED, but it is 13th
species in the EDGE list. Six species out of the
10 top ranked evolutionary distinct endangered
lineages, are endemic to Sri Lanka (Table 03).
However the ED of all these endemic species
are relatively low.
The order of ranking is again different when
considering the National Red List and Global
Red List for the calculations of EDGE score.
The Serendib Scops-owl which is 1st when
using Global Red List is the 23rd when using
National Red List, while Slaty-legged Crake
(Rallina eurizonoides) is 66th when using
Global Red List but is 1st when National Red
List is used. We stick to Global IUCN rankings
because the National Red List tend to
overemphasise several small populations of
globally widespread species such as
Slaty-legged Crake, Yellow-legged Green
Pigeon (Treron phoenicopterus) and Indian
Courser (Cursorius coromandelicus), all of
them are Critically Endangered in the Local
IUCN list due to small population size. On the
other hand, some of the range restricted Sri
Lankan endemics are lower in the National Red
List’s vulnerability index even though they are
range-restricted endangered species in the
IUCN Global list.
The evolutionary past of a clade can be
traced through phylogenetic trees. Such
phylogenetic trees can also be used to measure
the amount of evolutionary history captured by
its member species. Evolutionary Distinctness
(ED) and Evolutionary Distinct and Globally
Endangered Score (EDGE) are two such vital
parameters that could elucidate the
phylogenetic history captured in member
species. Using the total species recorded in
IBAs of Sri Lanka we constructed a
phylogenetic tree to evaluate the ED and EDGE
scores of Sri Lankan Birds. Ceylon Frogmouth
is the most evolutionary distinct (ED) species in
the island, while Serendib Scops-owl is the
most evolutionary distinct endangered lineage
(EDGE). Members of order Charadriiformes in
general have the lowest ED values.
ACKNOWLEDGEMENT
We are grateful to Dr. Praveen Karanth and
the members of the Evolving Phylo - Lab at the
Indian Institute of Science and Dr. Arne Mooers
at the Simon Fraser University, Canada for
assistance with the phylogenetic tools. The
Field Ornithology Group of Sri Lanka provided
the IBA database for this study. Department of
Zoology and Environment Sciences, University
of Colombo provided funding for DA and SS
for this study. We also thank Mr. Hasitha Perera
and Dr. Gehan Rajeev for providing bird images
and Dr. Nishanthi Perera and Dr. Hashendra
Kathriarrachchi for commenting on the manu-
script.
INTRODUCTION
Birds have evolved from a lineage led by
dinosaurs over a period of ~100 million years
(Brusatte et al., 2015). The explosive radiation
in this lineage however had been taken place in
~50 MYA, which made them highly diverged
with about 10,000 extant species (Jetz et al.,
2012). Of that about 500 species of birds, 5% of
the global avian diversity, is represented in Sri
Lanka (Rasmussen & Anderton, 2005). Sri
Lanka is a continental island in the Indian
Ocean which is periodically connected with the
mainland India throughout its geological history
(MacArthur & Wilson, 1967). As a result the
avifauna of the island is widely considered as a
subset of Indian Avifauna (Ripley et al., 1949;
Bossuyt et al., 2004). However Sri Lanka
carries a unique avifaunal diversity through
accommodating 34 endemic bird species
(Fernando et al., 2016, Rasmussen & Anderton,
2005). The endemicity birds in Sri Lanka
(7.43%) is highest in the region. About 240
resident species, 220 winter migrants and 40
pelagic seabirds comprise the rest of the bird
diversity of the Island (National Red List of Sri
Lanka, 2012). Does each of these 500 species of
birds found in Sri Lanka carry a similar
evolutionary significance in representing 100
million years of their evolutionary history?
The evolutionary history of a
phylogenetically distinct group of organisms
(clade) can be traced using a phylogenetic tree,
in which the tips and nodes of the tree stand for
descendant taxa and their common ancestors
respectively (Vellend et al., 2007). Nee and
May, (1997) suggested that the more distal
nodes (i.e. species) that a branch carries, the
lower the amount of evolutionary history
captured by each of its distal nodes in that
particular branch (Fig. 01). Based on this
principle several phylogenetic parameters are
being developed in the recent past to measure
how much evolutionary history is captured by a
single species (Box 01). Evolutionary
Distinctness (ED), and Evolutionary Distinct
and Globally Endangered Score (EDGE score)
are two of such key parameters that can be used
to quantify the amount of phylogenetic history
captured by the given entity (Jetz et al., 2014).
006May, 2017] EVOLUTIONARY DISTINCTIVENESS OF SRI LANKAN AVIFAUNA
In this paper the evolutionary distinctness of
Sri Lankan avifauna is quantified using a
phylogenetic tree constructed for all the 342
bird species that are found in 71 Important Bird
Areas (IBAs; www.birdlife.org/worldwide/
programmes/sites-ibas) of Sri Lanka. We
constructed the tree from DNA sequence
archives in global genetic databases
(www.birdtree.org) using bioinformatics tools
and higher-order phylogenetic backbones
(Hackett et al., 2008).
MATERIALS AND METHODS
Total species list, which contains all
recorded species in 71 IBAs was obtained from
the IBA database of the Field Ornithology
Group of Sri Lanka. The list was fed into the
option ‘Phylogeny subsets’ of ‘www.birdtree.
org’ and a set of 5000 phylogenetic trees was
generated. ‘Hackett All Species: a set of 10000
trees with 9993 OTUs each’, which refers to the
database of species in the study by Hackett et al.
(2008) that contains 10,000 trees each with
9,993 operational units was selected as the
source of trees.
To generate the grand tree for all 342
species recorded, we followed four main steps.
For the construction of the tree we combined
relaxed clock molecular trees of well supported
clades with a backbone which contained
representatives from each clade (Jetz et al.,
2012). As the first step each species was
assigned to one of the 158 clades which arise
from the 158 tips of the backbone trees. Then
relaxed-clock trees were constructed for each
clade. The species that do not have genetic
information were plugged in to their relevant
clades using the information obtained by
combining the relaxed clock trees and available
taxonomic information (Jetz et al., 2012). The
final tree was constructed by merging trees from
either of the previous two steps with time
calibrated relaxed molecular clock backbone
trees (Jetz et al., 2012; www.birdtree.org).
A consensus tree (Fig. 02) was generated
from the file of 5000 phylogenetic trees
generated by www.birdtree.org using
‘TreeAnnotator v1.8.2’ of the software BEAST
(BEAST v1.8.2). First 100 trees were discarded
as ‘burnin trees’. ‘User target tree’ was selected
as the target tree type while ‘Median heights’
was selected as the node heights. Posterior
probability for the tree was 0.75 (Drummond et
al., 2007). R platform (R Development Core
Team) was used to measure the Evolutionary
Distinctiveness (ED) and EDGE scores for each
species.
The consensus tree was generated using
‘Treeannotator’ and saved in .tre format. Using
the R codes below, the ED of all 342 species
were calculated.
To calculate the Evolutionary Distinctiveness
Originality<-evol.distinc
(tree,type="fair.proportion")
We used EDGE = ln(1+ED) + GE * ln(2), to
calculate the EDGE scores for each species in
the list (Isaac et al.,2007).
Where,
ED= Evolutionary Distinctiveness
GE= Red list category weight
(Least Concern=0, Near Threatened and
Conservation Dependent=1, Vulnerable=2,
Endangered=3, Critically Endangered=4)
We ranked all 342 species based on their ED
and EDGE values.
The global ED and EDGE scores of birds
were taken from Jetz et al. (2014).
RESULTS
According to our calculations the Ceylon
Frogmouth (B. moniliger), Malabar Trogon (H.
fasciatus), Indian Pitta (P. brachyura), Greater
Flamingo (P. roseus), Little Grebe (T.
ruficollis), Spot-billed Pelican (Pelecanus
philippensis), Eurasian Hoopoe (Upupa epops),
Osprey (Pandion haliaetus), Black-winged Kite
(Elanus caeruleus) and Oriental Bay-owl
(Phodilus badius) are the ten most evolutionary
distinct (ED) species of birds found in Sri Lanka
(Table 01, Fig. 03).
The ten most evolutionary distinct
endangered species (EDGE) of the country are
Serendib Scops-owl (O. thilohoffmanni),
Green-billed Coucal (C. chlororhynchus),
Ceylon Whistling-thrush (M. blighi), Lesser
Adjutant (L. javanicus), Spot-billed Pelican (P.
philippensis), Ceylon Blue Magpie (Urocissa
ornata), Red-faced Malkoha (Phaenicophaeus
pyrrhocephalus), Malabar Pied Hornbill
(Anthracoceros coronatus), Ceylon
Wood-pigeon (Columba torringtoniae) and
Black-headed Ibis (Threskiornis
melanocephalus) (Table 02, Fig 04).
Seabirds belong to Fig 04 the order
Charedriiformes such as the Roseate Tern
(Sterna dougallii), Common Tern (Sterna
hirundo), Sandwich Tern (Sterna
sandvicensis), Lesser Crested Tern (Sterna
bengalensis) and Great Crested Tern (Sterna
bergii) have the lowest evolutionary
significance and EDGE scores among Sri
Lankan birds.
DISCUSSION
Not all species carry the same evolutionary
significance because the members from
different clades of the tree of life have different
levels of phylogenetic isolation (Brusatte et al.,
2015). In birds, members of the order
Passeriformes have relatively low evolutionary
distinctiveness than that of some members of
non-passerine clades (Jetz et al., 2014). The
species with high evolutionary distinctiveness
(ED) mostly underwent relatively older
speciation events where the ones with low ED
have recent divergent history (Hackett et al.,
2008). Furthermore, species with lower ED
have diverged recently and are not isolated in
the tree of life as they have numerous close
relatives near its distal node (Redding et al.,
2008). Species that have higher ED are isolated
in the phylogenetic tree that is mainly due to
extinction of the member species. According to
the phylogenetic relationships of birds in Sri
Lanka (Fig. 02), it is clear that Ceylon
Frogmouth is isolated in the phylogenetic tree
and has speciated long ago. As a result Ceylon
Frogmouth has the greatest evolutionary
significance (75.2995) among Sri Lankan birds.
It is noteworthy that no endemic species is listed
as the top 10 species with highest ED (Table
01). The reason may be that these endemic
species have diverged recently and still they
have sister or closely related species in Sri
Lanka (Rasmussen & Anderton, 2005; Ripley &
Beehler, 1990). For example, Zosterops
ceylonensis (Highland White-eye) which is an
endemic species has Zosterops palpebrosus
(Oriental White-eye) as its sister species. The
ED of these two species are the same and is
relatively low (11.9007). Among the 34
endemic bird species of Sri Lanka (Table 03),
Ocyceros gingalensis (Ceylon Grey Hornbill)
has the highest ED (49.0085), followed by
Green-billed Coucal, Loriculus beryllinus
(Ceylon Lorikeet), Glaucidium castanonotum
(Chestnut-backed Owlet) and Galloperdix
bicalcarata (Ceylon Spurfowl). Among
endemics Sturnus albofrontatus (White-faced
Starling) has the lowest ED (11.7064) followed
by Chrysocolaptes stricklandi (Layard’s
Flameback), Gracula ptilogenys (Ceylon
Hill-myna), Turdoides rufescens (Ceylon Rufus
Babbler) and Highland White-eye.
The order of ranking is different between
the global ranking of ED and the Sri Lankan
ranking of ED. For example, Indian Pitta, which
ranks 3rd in the local ranking, is 10th when these
10 species are arranged according to their
global rankings. Osprey in the other hand ranks
8th in the local list, is 1st when it is taken in the
order of global rankings. The reason for this is
in the local context, Indian Pitta is a monotypic
genus, so its ED goes up when only the birds of
Sri Lanka are considered, but when consider the
global phylogeny, there are 30 species of pittas
(Fig. 02). In the case of Osprey, it is a
monotypic genus in both local (Fig. 02) and
global contexts. So the ED of Osprey is high
locally and globally. As described previously,
the EDGE score of a species depends on both
the ED and the IUCN red list status of that
species (Isaac et al., 2007). Therefore, to have a
high EDGE score, the species should be an
isolated node in the phylogenetic tree with a
globally threatened status. Our results showed
that the Serendib Scops-owl has the highest
EDGE score (5.26). Serendib Scops-owl
however has a relatively low ED (23.00) but it is
an endangered endemic. Ceylon Frogmouth
topped the list for highest ED, but it is 13th
species in the EDGE list. Six species out of the
10 top ranked evolutionary distinct endangered
lineages, are endemic to Sri Lanka (Table 03).
However the ED of all these endemic species
are relatively low.
The order of ranking is again different when
considering the National Red List and Global
Red List for the calculations of EDGE score.
The Serendib Scops-owl which is 1st when
using Global Red List is the 23rd when using
National Red List, while Slaty-legged Crake
(Rallina eurizonoides) is 66th when using
Global Red List but is 1st when National Red
List is used. We stick to Global IUCN rankings
because the National Red List tend to
overemphasise several small populations of
globally widespread species such as
Slaty-legged Crake, Yellow-legged Green
Pigeon (Treron phoenicopterus) and Indian
Courser (Cursorius coromandelicus), all of
them are Critically Endangered in the Local
IUCN list due to small population size. On the
other hand, some of the range restricted Sri
Lankan endemics are lower in the National Red
List’s vulnerability index even though they are
range-restricted endangered species in the
IUCN Global list.
The evolutionary past of a clade can be
traced through phylogenetic trees. Such
phylogenetic trees can also be used to measure
the amount of evolutionary history captured by
its member species. Evolutionary Distinctness
(ED) and Evolutionary Distinct and Globally
Endangered Score (EDGE) are two such vital
parameters that could elucidate the
phylogenetic history captured in member
species. Using the total species recorded in
IBAs of Sri Lanka we constructed a
phylogenetic tree to evaluate the ED and EDGE
scores of Sri Lankan Birds. Ceylon Frogmouth
is the most evolutionary distinct (ED) species in
the island, while Serendib Scops-owl is the
most evolutionary distinct endangered lineage
(EDGE). Members of order Charadriiformes in
general have the lowest ED values.
ACKNOWLEDGEMENT
We are grateful to Dr. Praveen Karanth and
the members of the Evolving Phylo - Lab at the
Indian Institute of Science and Dr. Arne Mooers
at the Simon Fraser University, Canada for
assistance with the phylogenetic tools. The
Field Ornithology Group of Sri Lanka provided
the IBA database for this study. Department of
Zoology and Environment Sciences, University
of Colombo provided funding for DA and SS
for this study. We also thank Mr. Hasitha Perera
and Dr. Gehan Rajeev for providing bird images
and Dr. Nishanthi Perera and Dr. Hashendra
Kathriarrachchi for commenting on the manu-
script.
FIGURE 4: Some of the most evolutionary distinct and endangered (EDGE) species of birds in Sri
Lanka: A. Serendib Scops-owl (O. thilohoffmani), B. Green-billed Coucal (C. chlororhynchus), C.
Ceylon Whistling-thrush (M. blighi), D. Lesser Adjutant (L. javanicus), and E. Ceylon Blue Magpie
(U. ornata).
Photo credit: Hasitha Perera (images A, D, E) and Gehan Rajeev (images B, C).
INTRODUCTION
Birds have evolved from a lineage led by
dinosaurs over a period of ~100 million years
(Brusatte et al., 2015). The explosive radiation
in this lineage however had been taken place in
~50 MYA, which made them highly diverged
with about 10,000 extant species (Jetz et al.,
2012). Of that about 500 species of birds, 5% of
the global avian diversity, is represented in Sri
Lanka (Rasmussen & Anderton, 2005). Sri
Lanka is a continental island in the Indian
Ocean which is periodically connected with the
mainland India throughout its geological history
(MacArthur & Wilson, 1967). As a result the
avifauna of the island is widely considered as a
subset of Indian Avifauna (Ripley et al., 1949;
Bossuyt et al., 2004). However Sri Lanka
carries a unique avifaunal diversity through
accommodating 34 endemic bird species
(Fernando et al., 2016, Rasmussen & Anderton,
2005). The endemicity birds in Sri Lanka
(7.43%) is highest in the region. About 240
resident species, 220 winter migrants and 40
pelagic seabirds comprise the rest of the bird
diversity of the Island (National Red List of Sri
Lanka, 2012). Does each of these 500 species of
birds found in Sri Lanka carry a similar
evolutionary significance in representing 100
million years of their evolutionary history?
The evolutionary history of a
phylogenetically distinct group of organisms
(clade) can be traced using a phylogenetic tree,
in which the tips and nodes of the tree stand for
descendant taxa and their common ancestors
respectively (Vellend et al., 2007). Nee and
May, (1997) suggested that the more distal
nodes (i.e. species) that a branch carries, the
lower the amount of evolutionary history
captured by each of its distal nodes in that
particular branch (Fig. 01). Based on this
principle several phylogenetic parameters are
being developed in the recent past to measure
how much evolutionary history is captured by a
single species (Box 01). Evolutionary
Distinctness (ED), and Evolutionary Distinct
and Globally Endangered Score (EDGE score)
are two of such key parameters that can be used
to quantify the amount of phylogenetic history
captured by the given entity (Jetz et al., 2014).
WILDLANKA [Vol. 5, No. 1007
In this paper the evolutionary distinctness of
Sri Lankan avifauna is quantified using a
phylogenetic tree constructed for all the 342
bird species that are found in 71 Important Bird
Areas (IBAs; www.birdlife.org/worldwide/
programmes/sites-ibas) of Sri Lanka. We
constructed the tree from DNA sequence
archives in global genetic databases
(www.birdtree.org) using bioinformatics tools
and higher-order phylogenetic backbones
(Hackett et al., 2008).
MATERIALS AND METHODS
Total species list, which contains all
recorded species in 71 IBAs was obtained from
the IBA database of the Field Ornithology
Group of Sri Lanka. The list was fed into the
option ‘Phylogeny subsets’ of ‘www.birdtree.
org’ and a set of 5000 phylogenetic trees was
generated. ‘Hackett All Species: a set of 10000
trees with 9993 OTUs each’, which refers to the
database of species in the study by Hackett et al.
(2008) that contains 10,000 trees each with
9,993 operational units was selected as the
source of trees.
To generate the grand tree for all 342
species recorded, we followed four main steps.
For the construction of the tree we combined
relaxed clock molecular trees of well supported
clades with a backbone which contained
representatives from each clade (Jetz et al.,
2012). As the first step each species was
assigned to one of the 158 clades which arise
from the 158 tips of the backbone trees. Then
relaxed-clock trees were constructed for each
clade. The species that do not have genetic
information were plugged in to their relevant
clades using the information obtained by
combining the relaxed clock trees and available
taxonomic information (Jetz et al., 2012). The
final tree was constructed by merging trees from
either of the previous two steps with time
calibrated relaxed molecular clock backbone
trees (Jetz et al., 2012; www.birdtree.org).
A consensus tree (Fig. 02) was generated
from the file of 5000 phylogenetic trees
generated by www.birdtree.org using
‘TreeAnnotator v1.8.2’ of the software BEAST
(BEAST v1.8.2). First 100 trees were discarded
as ‘burnin trees’. ‘User target tree’ was selected
as the target tree type while ‘Median heights’
was selected as the node heights. Posterior
probability for the tree was 0.75 (Drummond et
al., 2007). R platform (R Development Core
Team) was used to measure the Evolutionary
Distinctiveness (ED) and EDGE scores for each
species.
The consensus tree was generated using
‘Treeannotator’ and saved in .tre format. Using
the R codes below, the ED of all 342 species
were calculated.
To calculate the Evolutionary Distinctiveness
Originality<-evol.distinc
(tree,type="fair.proportion")
We used EDGE = ln(1+ED) + GE * ln(2), to
calculate the EDGE scores for each species in
the list (Isaac et al.,2007).
Where,
ED= Evolutionary Distinctiveness
GE= Red list category weight
(Least Concern=0, Near Threatened and
Conservation Dependent=1, Vulnerable=2,
Endangered=3, Critically Endangered=4)
We ranked all 342 species based on their ED
and EDGE values.
The global ED and EDGE scores of birds
were taken from Jetz et al. (2014).
RESULTS
According to our calculations the Ceylon
Frogmouth (B. moniliger), Malabar Trogon (H.
fasciatus), Indian Pitta (P. brachyura), Greater
Flamingo (P. roseus), Little Grebe (T.
ruficollis), Spot-billed Pelican (Pelecanus
philippensis), Eurasian Hoopoe (Upupa epops),
Osprey (Pandion haliaetus), Black-winged Kite
(Elanus caeruleus) and Oriental Bay-owl
(Phodilus badius) are the ten most evolutionary
distinct (ED) species of birds found in Sri Lanka
(Table 01, Fig. 03).
TABLE 2: Description of 10 most evolutionary distinct endangered lineages (EDGE) of birds in Sri
Lanka
Local Global Scientific Name Common IUCN status Breeding
Rank Rank English Name Status
01 406 Otus thilohoffmanni Serendib Scops-owl Endangered Endemic
02 248 Centropus chlororhynchus Green-billed Coucal Vulnerable Endemic
03 504 Myophonus blighi Ceylon Endangered Endemic
Whistling-thrush
04 223 Leptoptilos javanicus Lesser Adjutant Vulnerable Breeding
Resident
05 557 Pelecanus philippensis Spot-billed Pelican Near Breeding
Threatened Resident
06 1079 Urocissa ornata Ceylon Vulnerable Endemic
Blue Magpie
07 460 Phaenicophaeus Red-faced Malkoha Vulnerable Endemic
pyrrhocephalus
08 1222 Anthracoceros coronatus Malabar Pied Near Breeding
Hornbill Threatened Resident
09 1233 Columba torringtoniae Ceylon Vulnerable Endemic
Wood-pigeon
10 1022 Threskiornis Black-headed Ibis Near Breeding
melanocephalus Threatened Resident
The ten most evolutionary distinct
endangered species (EDGE) of the country are
Serendib Scops-owl (O. thilohoffmanni),
Green-billed Coucal (C. chlororhynchus),
Ceylon Whistling-thrush (M. blighi), Lesser
Adjutant (L. javanicus), Spot-billed Pelican (P.
philippensis), Ceylon Blue Magpie (Urocissa
ornata), Red-faced Malkoha (Phaenicophaeus
pyrrhocephalus), Malabar Pied Hornbill
(Anthracoceros coronatus), Ceylon
Wood-pigeon (Columba torringtoniae) and
Black-headed Ibis (Threskiornis
melanocephalus) (Table 02, Fig 04).
Seabirds belong to Fig 04 the order
Charedriiformes such as the Roseate Tern
(Sterna dougallii), Common Tern (Sterna
hirundo), Sandwich Tern (Sterna
sandvicensis), Lesser Crested Tern (Sterna
bengalensis) and Great Crested Tern (Sterna
bergii) have the lowest evolutionary
significance and EDGE scores among Sri
Lankan birds.
DISCUSSION
Not all species carry the same evolutionary
significance because the members from
different clades of the tree of life have different
levels of phylogenetic isolation (Brusatte et al.,
2015). In birds, members of the order
Passeriformes have relatively low evolutionary
distinctiveness than that of some members of
non-passerine clades (Jetz et al., 2014). The
species with high evolutionary distinctiveness
(ED) mostly underwent relatively older
speciation events where the ones with low ED
have recent divergent history (Hackett et al.,
2008). Furthermore, species with lower ED
have diverged recently and are not isolated in
the tree of life as they have numerous close
relatives near its distal node (Redding et al.,
2008). Species that have higher ED are isolated
in the phylogenetic tree that is mainly due to
extinction of the member species. According to
the phylogenetic relationships of birds in Sri
Lanka (Fig. 02), it is clear that Ceylon
Frogmouth is isolated in the phylogenetic tree
and has speciated long ago. As a result Ceylon
Frogmouth has the greatest evolutionary
significance (75.2995) among Sri Lankan birds.
It is noteworthy that no endemic species is listed
as the top 10 species with highest ED (Table
01). The reason may be that these endemic
species have diverged recently and still they
have sister or closely related species in Sri
Lanka (Rasmussen & Anderton, 2005; Ripley &
Beehler, 1990). For example, Zosterops
ceylonensis (Highland White-eye) which is an
endemic species has Zosterops palpebrosus
(Oriental White-eye) as its sister species. The
ED of these two species are the same and is
relatively low (11.9007). Among the 34
endemic bird species of Sri Lanka (Table 03),
Ocyceros gingalensis (Ceylon Grey Hornbill)
has the highest ED (49.0085), followed by
Green-billed Coucal, Loriculus beryllinus
(Ceylon Lorikeet), Glaucidium castanonotum
(Chestnut-backed Owlet) and Galloperdix
bicalcarata (Ceylon Spurfowl). Among
endemics Sturnus albofrontatus (White-faced
Starling) has the lowest ED (11.7064) followed
by Chrysocolaptes stricklandi (Layard’s
Flameback), Gracula ptilogenys (Ceylon
Hill-myna), Turdoides rufescens (Ceylon Rufus
Babbler) and Highland White-eye.
The order of ranking is different between
the global ranking of ED and the Sri Lankan
ranking of ED. For example, Indian Pitta, which
ranks 3rd in the local ranking, is 10th when these
10 species are arranged according to their
global rankings. Osprey in the other hand ranks
8th in the local list, is 1st when it is taken in the
order of global rankings. The reason for this is
in the local context, Indian Pitta is a monotypic
genus, so its ED goes up when only the birds of
Sri Lanka are considered, but when consider the
global phylogeny, there are 30 species of pittas
(Fig. 02). In the case of Osprey, it is a
monotypic genus in both local (Fig. 02) and
global contexts. So the ED of Osprey is high
locally and globally. As described previously,
the EDGE score of a species depends on both
the ED and the IUCN red list status of that
species (Isaac et al., 2007). Therefore, to have a
high EDGE score, the species should be an
isolated node in the phylogenetic tree with a
globally threatened status. Our results showed
that the Serendib Scops-owl has the highest
EDGE score (5.26). Serendib Scops-owl
however has a relatively low ED (23.00) but it is
an endangered endemic. Ceylon Frogmouth
topped the list for highest ED, but it is 13th
species in the EDGE list. Six species out of the
10 top ranked evolutionary distinct endangered
lineages, are endemic to Sri Lanka (Table 03).
However the ED of all these endemic species
are relatively low.
The order of ranking is again different when
considering the National Red List and Global
Red List for the calculations of EDGE score.
The Serendib Scops-owl which is 1st when
using Global Red List is the 23rd when using
National Red List, while Slaty-legged Crake
(Rallina eurizonoides) is 66th when using
Global Red List but is 1st when National Red
List is used. We stick to Global IUCN rankings
because the National Red List tend to
overemphasise several small populations of
globally widespread species such as
Slaty-legged Crake, Yellow-legged Green
Pigeon (Treron phoenicopterus) and Indian
Courser (Cursorius coromandelicus), all of
them are Critically Endangered in the Local
IUCN list due to small population size. On the
other hand, some of the range restricted Sri
Lankan endemics are lower in the National Red
List’s vulnerability index even though they are
range-restricted endangered species in the
IUCN Global list.
The evolutionary past of a clade can be
traced through phylogenetic trees. Such
phylogenetic trees can also be used to measure
the amount of evolutionary history captured by
its member species. Evolutionary Distinctness
(ED) and Evolutionary Distinct and Globally
Endangered Score (EDGE) are two such vital
parameters that could elucidate the
phylogenetic history captured in member
species. Using the total species recorded in
IBAs of Sri Lanka we constructed a
phylogenetic tree to evaluate the ED and EDGE
scores of Sri Lankan Birds. Ceylon Frogmouth
is the most evolutionary distinct (ED) species in
the island, while Serendib Scops-owl is the
most evolutionary distinct endangered lineage
(EDGE). Members of order Charadriiformes in
general have the lowest ED values.
ACKNOWLEDGEMENT
We are grateful to Dr. Praveen Karanth and
the members of the Evolving Phylo - Lab at the
Indian Institute of Science and Dr. Arne Mooers
at the Simon Fraser University, Canada for
assistance with the phylogenetic tools. The
Field Ornithology Group of Sri Lanka provided
the IBA database for this study. Department of
Zoology and Environment Sciences, University
of Colombo provided funding for DA and SS
for this study. We also thank Mr. Hasitha Perera
and Dr. Gehan Rajeev for providing bird images
and Dr. Nishanthi Perera and Dr. Hashendra
Kathriarrachchi for commenting on the manu-
script.
INTRODUCTION
Birds have evolved from a lineage led by
dinosaurs over a period of ~100 million years
(Brusatte et al., 2015). The explosive radiation
in this lineage however had been taken place in
~50 MYA, which made them highly diverged
with about 10,000 extant species (Jetz et al.,
2012). Of that about 500 species of birds, 5% of
the global avian diversity, is represented in Sri
Lanka (Rasmussen & Anderton, 2005). Sri
Lanka is a continental island in the Indian
Ocean which is periodically connected with the
mainland India throughout its geological history
(MacArthur & Wilson, 1967). As a result the
avifauna of the island is widely considered as a
subset of Indian Avifauna (Ripley et al., 1949;
Bossuyt et al., 2004). However Sri Lanka
carries a unique avifaunal diversity through
accommodating 34 endemic bird species
(Fernando et al., 2016, Rasmussen & Anderton,
2005). The endemicity birds in Sri Lanka
(7.43%) is highest in the region. About 240
resident species, 220 winter migrants and 40
pelagic seabirds comprise the rest of the bird
diversity of the Island (National Red List of Sri
Lanka, 2012). Does each of these 500 species of
birds found in Sri Lanka carry a similar
evolutionary significance in representing 100
million years of their evolutionary history?
The evolutionary history of a
phylogenetically distinct group of organisms
(clade) can be traced using a phylogenetic tree,
in which the tips and nodes of the tree stand for
descendant taxa and their common ancestors
respectively (Vellend et al., 2007). Nee and
May, (1997) suggested that the more distal
nodes (i.e. species) that a branch carries, the
lower the amount of evolutionary history
captured by each of its distal nodes in that
particular branch (Fig. 01). Based on this
principle several phylogenetic parameters are
being developed in the recent past to measure
how much evolutionary history is captured by a
single species (Box 01). Evolutionary
Distinctness (ED), and Evolutionary Distinct
and Globally Endangered Score (EDGE score)
are two of such key parameters that can be used
to quantify the amount of phylogenetic history
captured by the given entity (Jetz et al., 2014).
008May, 2017] EVOLUTIONARY DISTINCTIVENESS OF SRI LANKAN AVIFAUNA
In this paper the evolutionary distinctness of
Sri Lankan avifauna is quantified using a
phylogenetic tree constructed for all the 342
bird species that are found in 71 Important Bird
Areas (IBAs; www.birdlife.org/worldwide/
programmes/sites-ibas) of Sri Lanka. We
constructed the tree from DNA sequence
archives in global genetic databases
(www.birdtree.org) using bioinformatics tools
and higher-order phylogenetic backbones
(Hackett et al., 2008).
MATERIALS AND METHODS
Total species list, which contains all
recorded species in 71 IBAs was obtained from
the IBA database of the Field Ornithology
Group of Sri Lanka. The list was fed into the
option ‘Phylogeny subsets’ of ‘www.birdtree.
org’ and a set of 5000 phylogenetic trees was
generated. ‘Hackett All Species: a set of 10000
trees with 9993 OTUs each’, which refers to the
database of species in the study by Hackett et al.
(2008) that contains 10,000 trees each with
9,993 operational units was selected as the
source of trees.
To generate the grand tree for all 342
species recorded, we followed four main steps.
For the construction of the tree we combined
relaxed clock molecular trees of well supported
clades with a backbone which contained
representatives from each clade (Jetz et al.,
2012). As the first step each species was
assigned to one of the 158 clades which arise
from the 158 tips of the backbone trees. Then
relaxed-clock trees were constructed for each
clade. The species that do not have genetic
information were plugged in to their relevant
clades using the information obtained by
combining the relaxed clock trees and available
taxonomic information (Jetz et al., 2012). The
final tree was constructed by merging trees from
either of the previous two steps with time
calibrated relaxed molecular clock backbone
trees (Jetz et al., 2012; www.birdtree.org).
A consensus tree (Fig. 02) was generated
from the file of 5000 phylogenetic trees
generated by www.birdtree.org using
‘TreeAnnotator v1.8.2’ of the software BEAST
(BEAST v1.8.2). First 100 trees were discarded
as ‘burnin trees’. ‘User target tree’ was selected
as the target tree type while ‘Median heights’
was selected as the node heights. Posterior
probability for the tree was 0.75 (Drummond et
al., 2007). R platform (R Development Core
Team) was used to measure the Evolutionary
Distinctiveness (ED) and EDGE scores for each
species.
The consensus tree was generated using
‘Treeannotator’ and saved in .tre format. Using
the R codes below, the ED of all 342 species
were calculated.
To calculate the Evolutionary Distinctiveness
Originality<-evol.distinc
(tree,type="fair.proportion")
We used EDGE = ln(1+ED) + GE * ln(2), to
calculate the EDGE scores for each species in
the list (Isaac et al.,2007).
Where,
ED= Evolutionary Distinctiveness
GE= Red list category weight
(Least Concern=0, Near Threatened and
Conservation Dependent=1, Vulnerable=2,
Endangered=3, Critically Endangered=4)
We ranked all 342 species based on their ED
and EDGE values.
The global ED and EDGE scores of birds
were taken from Jetz et al. (2014).
RESULTS
According to our calculations the Ceylon
Frogmouth (B. moniliger), Malabar Trogon (H.
fasciatus), Indian Pitta (P. brachyura), Greater
Flamingo (P. roseus), Little Grebe (T.
ruficollis), Spot-billed Pelican (Pelecanus
philippensis), Eurasian Hoopoe (Upupa epops),
Osprey (Pandion haliaetus), Black-winged Kite
(Elanus caeruleus) and Oriental Bay-owl
(Phodilus badius) are the ten most evolutionary
distinct (ED) species of birds found in Sri Lanka
(Table 01, Fig. 03).
TABLE 3: Evolutionary distinctiveness and EDGE scores of 34 endemic species of birds in Sri
Lanka
Rank Scientific Name Common IUCN ED EDGE
English Name Status
1 Ocyceros gingalensis Ceylon Grey Hornbill LC 49.01 3.91
2 Centropus chlororhynchus Green-billed Coucal VU 42.13 5.15
3 Loriculus beryllinus Ceylon Lorikeet LC 41.42 3.75
4 Glaucidium castanonotum Chestnut-backed Owlet NT 34.25 4.26
5 Galloperdix bicalcarata Ceylon Spurfowl LC 28.26 3.38
6 Gallus lafayetii Ceylon Junglefowl LC 25.16 3.26
7 Urocissa ornata Ceylon Blue Magpie VU 24.38 4.62
8
Phaenicophaeus pyrrhocephalus
Red-faced Malkoha VU 24.15 4.61
9 Psittacula calthropae Layard’s Parakeet LC 24.04 3.22
10 Tephrodornis pondicerianu Common Woodshrike LC 23.74 3.21
11 Dicaeum vincens Legge’s Flowerpecker NT 23.33 3.89
12 Otus thilohoffmanni Serendib Scops-owl EN 22.99 5.26
13 Columba torringtoniae Ceylon Wood-pigeon VU 22.64 4.55
14 Treron pompadora Sri Lanka Green-pigeon LC 22.50 3.16
15 Megalaima flavifrons Yellow-fronted Barbet LC 21.38 3.11
16 Hirundo daurica Red-rumped Swallow LC 20.75 3.088
17 Zoothera imbricata Sri Lanka Scaly Thrush NT 20.55 3.76
18 Megalaima rubricapillus Crimson-fronted Barbet LC 19.26 3.01
19 Bradypterus palliseri Ceylon Bush-warbler NT 18.92 3.68
20 Pycnonotus melanicterus Black-capped Bulbul LC 18.55 2.98
21 Pycnonotus penicillatus Yellow-eared Bulbul NT 18.41 3.66
22 Myophonus blighi Ceylon Whistling-thrush EN 18.38 5.04
23 Pellorneum fuscocapillus Brown-capped Babbler LC 18.19 2.95
24 Eumyias sordidus Dusky-blue Flycatcher NT 17.82 3.63
25 Dinopium psarodes Red-backed Flameback LC 16.72 2.87
26 Pomatorhinus melanurus Sri Lanka Scimitar-babbler LC 16.18 2.84
27 Zoothera spiloptera Spot-winged Thrush NT 15.87 3.52
28 Garrulax cinereifrons Ashy-headed Laughingthrush VU 14.93 4.15
29 Chrysocolaptes stricklandi Layard’s Flameback LC 14.21 2.72
30 Gracula ptilogenys Ceylon Hill-Myna NT 14.02 3.40
31 Turdoides rufescens Ceylon Rufus Babbler NT 13.11 3.34
32 Zosterops ceylonensis Highland White-eye LC 11.90 2.56
33 Sturnus albofrontatus White-faced Starling VU 11.70 3.93
34 Dicrurus lophorhinus Ceylon Crested Drongo LC 19.11 3.00
The ten most evolutionary distinct
endangered species (EDGE) of the country are
Serendib Scops-owl (O. thilohoffmanni),
Green-billed Coucal (C. chlororhynchus),
Ceylon Whistling-thrush (M. blighi), Lesser
Adjutant (L. javanicus), Spot-billed Pelican (P.
philippensis), Ceylon Blue Magpie (Urocissa
ornata), Red-faced Malkoha (Phaenicophaeus
pyrrhocephalus), Malabar Pied Hornbill
(Anthracoceros coronatus), Ceylon
Wood-pigeon (Columba torringtoniae) and
Black-headed Ibis (Threskiornis
melanocephalus) (Table 02, Fig 04).
Seabirds belong to Fig 04 the order
Charedriiformes such as the Roseate Tern
(Sterna dougallii), Common Tern (Sterna
hirundo), Sandwich Tern (Sterna
sandvicensis), Lesser Crested Tern (Sterna
bengalensis) and Great Crested Tern (Sterna
bergii) have the lowest evolutionary
significance and EDGE scores among Sri
Lankan birds.
DISCUSSION
Not all species carry the same evolutionary
significance because the members from
different clades of the tree of life have different
levels of phylogenetic isolation (Brusatte et al.,
2015). In birds, members of the order
Passeriformes have relatively low evolutionary
distinctiveness than that of some members of
non-passerine clades (Jetz et al., 2014). The
species with high evolutionary distinctiveness
(ED) mostly underwent relatively older
speciation events where the ones with low ED
have recent divergent history (Hackett et al.,
2008). Furthermore, species with lower ED
have diverged recently and are not isolated in
the tree of life as they have numerous close
relatives near its distal node (Redding et al.,
2008). Species that have higher ED are isolated
in the phylogenetic tree that is mainly due to
extinction of the member species. According to
the phylogenetic relationships of birds in Sri
Lanka (Fig. 02), it is clear that Ceylon
Frogmouth is isolated in the phylogenetic tree
and has speciated long ago. As a result Ceylon
Frogmouth has the greatest evolutionary
significance (75.2995) among Sri Lankan birds.
It is noteworthy that no endemic species is listed
as the top 10 species with highest ED (Table
01). The reason may be that these endemic
species have diverged recently and still they
have sister or closely related species in Sri
Lanka (Rasmussen & Anderton, 2005; Ripley &
Beehler, 1990). For example, Zosterops
ceylonensis (Highland White-eye) which is an
endemic species has Zosterops palpebrosus
(Oriental White-eye) as its sister species. The
ED of these two species are the same and is
relatively low (11.9007). Among the 34
endemic bird species of Sri Lanka (Table 03),
Ocyceros gingalensis (Ceylon Grey Hornbill)
has the highest ED (49.0085), followed by
Green-billed Coucal, Loriculus beryllinus
(Ceylon Lorikeet), Glaucidium castanonotum
(Chestnut-backed Owlet) and Galloperdix
bicalcarata (Ceylon Spurfowl). Among
endemics Sturnus albofrontatus (White-faced
Starling) has the lowest ED (11.7064) followed
by Chrysocolaptes stricklandi (Layard’s
Flameback), Gracula ptilogenys (Ceylon
Hill-myna), Turdoides rufescens (Ceylon Rufus
Babbler) and Highland White-eye.
The order of ranking is different between
the global ranking of ED and the Sri Lankan
ranking of ED. For example, Indian Pitta, which
ranks 3rd in the local ranking, is 10th when these
10 species are arranged according to their
global rankings. Osprey in the other hand ranks
8th in the local list, is 1st when it is taken in the
order of global rankings. The reason for this is
in the local context, Indian Pitta is a monotypic
genus, so its ED goes up when only the birds of
Sri Lanka are considered, but when consider the
global phylogeny, there are 30 species of pittas
(Fig. 02). In the case of Osprey, it is a
monotypic genus in both local (Fig. 02) and
global contexts. So the ED of Osprey is high
locally and globally. As described previously,
the EDGE score of a species depends on both
the ED and the IUCN red list status of that
species (Isaac et al., 2007). Therefore, to have a
high EDGE score, the species should be an
isolated node in the phylogenetic tree with a
globally threatened status. Our results showed
that the Serendib Scops-owl has the highest
EDGE score (5.26). Serendib Scops-owl
however has a relatively low ED (23.00) but it is
an endangered endemic. Ceylon Frogmouth
topped the list for highest ED, but it is 13th
species in the EDGE list. Six species out of the
10 top ranked evolutionary distinct endangered
lineages, are endemic to Sri Lanka (Table 03).
However the ED of all these endemic species
are relatively low.
The order of ranking is again different when
considering the National Red List and Global
Red List for the calculations of EDGE score.
The Serendib Scops-owl which is 1st when
using Global Red List is the 23rd when using
National Red List, while Slaty-legged Crake
(Rallina eurizonoides) is 66th when using
Global Red List but is 1st when National Red
List is used. We stick to Global IUCN rankings
because the National Red List tend to
overemphasise several small populations of
globally widespread species such as
Slaty-legged Crake, Yellow-legged Green
Pigeon (Treron phoenicopterus) and Indian
Courser (Cursorius coromandelicus), all of
them are Critically Endangered in the Local
IUCN list due to small population size. On the
other hand, some of the range restricted Sri
Lankan endemics are lower in the National Red
List’s vulnerability index even though they are
range-restricted endangered species in the
IUCN Global list.
The evolutionary past of a clade can be
traced through phylogenetic trees. Such
phylogenetic trees can also be used to measure
the amount of evolutionary history captured by
its member species. Evolutionary Distinctness
(ED) and Evolutionary Distinct and Globally
Endangered Score (EDGE) are two such vital
parameters that could elucidate the
phylogenetic history captured in member
species. Using the total species recorded in
IBAs of Sri Lanka we constructed a
phylogenetic tree to evaluate the ED and EDGE
scores of Sri Lankan Birds. Ceylon Frogmouth
is the most evolutionary distinct (ED) species in
the island, while Serendib Scops-owl is the
most evolutionary distinct endangered lineage
(EDGE). Members of order Charadriiformes in
general have the lowest ED values.
ACKNOWLEDGEMENT
We are grateful to Dr. Praveen Karanth and
the members of the Evolving Phylo - Lab at the
Indian Institute of Science and Dr. Arne Mooers
at the Simon Fraser University, Canada for
assistance with the phylogenetic tools. The
Field Ornithology Group of Sri Lanka provided
the IBA database for this study. Department of
Zoology and Environment Sciences, University
of Colombo provided funding for DA and SS
for this study. We also thank Mr. Hasitha Perera
and Dr. Gehan Rajeev for providing bird images
and Dr. Nishanthi Perera and Dr. Hashendra
Kathriarrachchi for commenting on the manu-
script.
INTRODUCTION
Birds have evolved from a lineage led by
dinosaurs over a period of ~100 million years
(Brusatte et al., 2015). The explosive radiation
in this lineage however had been taken place in
~50 MYA, which made them highly diverged
with about 10,000 extant species (Jetz et al.,
2012). Of that about 500 species of birds, 5% of
the global avian diversity, is represented in Sri
Lanka (Rasmussen & Anderton, 2005). Sri
Lanka is a continental island in the Indian
Ocean which is periodically connected with the
mainland India throughout its geological history
(MacArthur & Wilson, 1967). As a result the
avifauna of the island is widely considered as a
subset of Indian Avifauna (Ripley et al., 1949;
Bossuyt et al., 2004). However Sri Lanka
carries a unique avifaunal diversity through
accommodating 34 endemic bird species
(Fernando et al., 2016, Rasmussen & Anderton,
2005). The endemicity birds in Sri Lanka
(7.43%) is highest in the region. About 240
resident species, 220 winter migrants and 40
pelagic seabirds comprise the rest of the bird
diversity of the Island (National Red List of Sri
Lanka, 2012). Does each of these 500 species of
birds found in Sri Lanka carry a similar
evolutionary significance in representing 100
million years of their evolutionary history?
The evolutionary history of a
phylogenetically distinct group of organisms
(clade) can be traced using a phylogenetic tree,
in which the tips and nodes of the tree stand for
descendant taxa and their common ancestors
respectively (Vellend et al., 2007). Nee and
May, (1997) suggested that the more distal
nodes (i.e. species) that a branch carries, the
lower the amount of evolutionary history
captured by each of its distal nodes in that
particular branch (Fig. 01). Based on this
principle several phylogenetic parameters are
being developed in the recent past to measure
how much evolutionary history is captured by a
single species (Box 01). Evolutionary
Distinctness (ED), and Evolutionary Distinct
and Globally Endangered Score (EDGE score)
are two of such key parameters that can be used
to quantify the amount of phylogenetic history
captured by the given entity (Jetz et al., 2014).
WILDLANKA [Vol. 5, No. 1009
REFERENCES
Bossuyt, F., and M. Meegaskumbura, et. al.,
(2004). Local endemism within the
Western Ghats-Sri Lanka biodiversity
hotspot. Science, 306(5695): 479–81.
Brusatte, S. L., J. K. O’Connor, and E. D. Jarvis,
(2015). The origin and diversification of
birds. Current Biology, 25(19):
R888-R898.
Butchart, S. H. M., A. J. Stattersfield, L. A.
Bennun, S. M. Shutes, H. R. Akc, J. E.
M. Baillie, and G. M. Mace, (2010).
Measuring Global Trends in the Status
In this paper the evolutionary distinctness of
Sri Lankan avifauna is quantified using a
phylogenetic tree constructed for all the 342
bird species that are found in 71 Important Bird
Areas (IBAs; www.birdlife.org/worldwide/
programmes/sites-ibas) of Sri Lanka. We
constructed the tree from DNA sequence
archives in global genetic databases
(www.birdtree.org) using bioinformatics tools
and higher-order phylogenetic backbones
(Hackett et al., 2008).
MATERIALS AND METHODS
Total species list, which contains all
recorded species in 71 IBAs was obtained from
the IBA database of the Field Ornithology
Group of Sri Lanka. The list was fed into the
option ‘Phylogeny subsets’ of ‘www.birdtree.
org’ and a set of 5000 phylogenetic trees was
generated. ‘Hackett All Species: a set of 10000
trees with 9993 OTUs each’, which refers to the
database of species in the study by Hackett et al.
(2008) that contains 10,000 trees each with
9,993 operational units was selected as the
source of trees.
To generate the grand tree for all 342
species recorded, we followed four main steps.
For the construction of the tree we combined
relaxed clock molecular trees of well supported
clades with a backbone which contained
representatives from each clade (Jetz et al.,
2012). As the first step each species was
assigned to one of the 158 clades which arise
from the 158 tips of the backbone trees. Then
relaxed-clock trees were constructed for each
clade. The species that do not have genetic
information were plugged in to their relevant
clades using the information obtained by
combining the relaxed clock trees and available
taxonomic information (Jetz et al., 2012). The
final tree was constructed by merging trees from
either of the previous two steps with time
calibrated relaxed molecular clock backbone
trees (Jetz et al., 2012; www.birdtree.org).
A consensus tree (Fig. 02) was generated
from the file of 5000 phylogenetic trees
generated by www.birdtree.org using
‘TreeAnnotator v1.8.2’ of the software BEAST
(BEAST v1.8.2). First 100 trees were discarded
as ‘burnin trees’. ‘User target tree’ was selected
as the target tree type while ‘Median heights’
was selected as the node heights. Posterior
probability for the tree was 0.75 (Drummond et
al., 2007). R platform (R Development Core
Team) was used to measure the Evolutionary
Distinctiveness (ED) and EDGE scores for each
species.
The consensus tree was generated using
‘Treeannotator’ and saved in .tre format. Using
the R codes below, the ED of all 342 species
were calculated.
of Biodiversity : Red List Indices for
Birds, 2(12): doi.org/10.1371/journal.
pbio.0020383.
Drummond, A. J., S. Y. W. Ho, N. Rawlence,
and A. Rambaut, (2007). A rough guide
to BEAST 1(4): University of Auckland,
Auckland, New Zealand.
Fernando S.P., D.E. Irwin, and S.S.
Seneviratne, 2016. Phenotypic and
genetic analysis support distinct species
status of the Red-backed Woodpecker
(Lesser Sri Lanka Flameback:
Dinopium psarodes) of Sri Lanka Auk:
Ornithological Advance 133:497-511
Hackett, S. J., R. T. Kimball, S. Reddy, R. C.
Bowie, E. L. Braun, M. J. Braun, and C.
J. Huddleston, (2008). A phylogenomic
study of birds reveals their evolutionary
history. Science, 320(5884):1763-
1768.
Isaac, N. J. B., S. T. Turvey, B. Collen, C.
Waterma, and J. E. M. Baillie, (2007).
Mammals on the EDGE: Conservation
Priorities Based on Threat and
Phylogeny, (3):Doi.org/10.1371/
journal.pone.0000296.
Jetz, W., G. H. Thomas, J. B. Joy, K. Hartmann,
and A. O. Mooers, (2012). The global
diversity of birds in space and time.
Nature, 491(7424):444-448.
Jetz, W., G. H. Thomas, J. B. Joy, D. W.
Redding, K. Hartmann, and A. O.
Mooers, (2014). Global Distribution
and Conservation of Evolutionary
Distinctness in Birds. Current Biology,
24(9):919–930. Doi.org/10.1016/ j.cub.
2014.03.011.
MacArthur, R. H. and E. O. Wilson, (1967). The
Theory of Island Biogeography. N.J.
Princeton, Princeton University Press.
National Red List of Sri Lanka 2012. World
Conservation Union (IUCN) in Sri
Lanka and the Ministry of Environment
and Natural Resources, Government of
Sri Lanka.
Nee, S., and R. M. May, (1997). Extinction and
the Loss of Evolutionary History.
Science, 278(5338):692–694. doi.org/
10.1126/science.278.5338.692.
To calculate the Evolutionary Distinctiveness
Originality<-evol.distinc
(tree,type="fair.proportion")
We used EDGE = ln(1+ED) + GE * ln(2), to
calculate the EDGE scores for each species in
the list (Isaac et al.,2007).
Where,
ED= Evolutionary Distinctiveness
GE= Red list category weight
(Least Concern=0, Near Threatened and
Conservation Dependent=1, Vulnerable=2,
Endangered=3, Critically Endangered=4)
We ranked all 342 species based on their ED
and EDGE values.
The global ED and EDGE scores of birds
were taken from Jetz et al. (2014).
RESULTS
According to our calculations the Ceylon
Frogmouth (B. moniliger), Malabar Trogon (H.
fasciatus), Indian Pitta (P. brachyura), Greater
Flamingo (P. roseus), Little Grebe (T.
ruficollis), Spot-billed Pelican (Pelecanus
philippensis), Eurasian Hoopoe (Upupa epops),
Osprey (Pandion haliaetus), Black-winged Kite
(Elanus caeruleus) and Oriental Bay-owl
(Phodilus badius) are the ten most evolutionary
distinct (ED) species of birds found in Sri Lanka
(Table 01, Fig. 03).
The ten most evolutionary distinct
endangered species (EDGE) of the country are
Serendib Scops-owl (O. thilohoffmanni),
Green-billed Coucal (C. chlororhynchus),
Ceylon Whistling-thrush (M. blighi), Lesser
Adjutant (L. javanicus), Spot-billed Pelican (P.
philippensis), Ceylon Blue Magpie (Urocissa
ornata), Red-faced Malkoha (Phaenicophaeus
pyrrhocephalus), Malabar Pied Hornbill
(Anthracoceros coronatus), Ceylon
Wood-pigeon (Columba torringtoniae) and
Black-headed Ibis (Threskiornis
melanocephalus) (Table 02, Fig 04).
Seabirds belong to Fig 04 the order
Charedriiformes such as the Roseate Tern
(Sterna dougallii), Common Tern (Sterna
hirundo), Sandwich Tern (Sterna
sandvicensis), Lesser Crested Tern (Sterna
bengalensis) and Great Crested Tern (Sterna
bergii) have the lowest evolutionary
significance and EDGE scores among Sri
Lankan birds.
DISCUSSION
Not all species carry the same evolutionary
significance because the members from
different clades of the tree of life have different
levels of phylogenetic isolation (Brusatte et al.,
2015). In birds, members of the order
Passeriformes have relatively low evolutionary
distinctiveness than that of some members of
non-passerine clades (Jetz et al., 2014). The
species with high evolutionary distinctiveness
(ED) mostly underwent relatively older
speciation events where the ones with low ED
have recent divergent history (Hackett et al.,
2008). Furthermore, species with lower ED
have diverged recently and are not isolated in
the tree of life as they have numerous close
relatives near its distal node (Redding et al.,
2008). Species that have higher ED are isolated
in the phylogenetic tree that is mainly due to
extinction of the member species. According to
the phylogenetic relationships of birds in Sri
Lanka (Fig. 02), it is clear that Ceylon
Frogmouth is isolated in the phylogenetic tree
and has speciated long ago. As a result Ceylon
Frogmouth has the greatest evolutionary
significance (75.2995) among Sri Lankan birds.
It is noteworthy that no endemic species is listed
as the top 10 species with highest ED (Table
01). The reason may be that these endemic
species have diverged recently and still they
have sister or closely related species in Sri
Lanka (Rasmussen & Anderton, 2005; Ripley &
Beehler, 1990). For example, Zosterops
ceylonensis (Highland White-eye) which is an
endemic species has Zosterops palpebrosus
(Oriental White-eye) as its sister species. The
ED of these two species are the same and is
relatively low (11.9007). Among the 34
endemic bird species of Sri Lanka (Table 03),
Ocyceros gingalensis (Ceylon Grey Hornbill)
has the highest ED (49.0085), followed by
Green-billed Coucal, Loriculus beryllinus
(Ceylon Lorikeet), Glaucidium castanonotum
(Chestnut-backed Owlet) and Galloperdix
bicalcarata (Ceylon Spurfowl). Among
endemics Sturnus albofrontatus (White-faced
Starling) has the lowest ED (11.7064) followed
by Chrysocolaptes stricklandi (Layard’s
Flameback), Gracula ptilogenys (Ceylon
Hill-myna), Turdoides rufescens (Ceylon Rufus
Babbler) and Highland White-eye.
The order of ranking is different between
the global ranking of ED and the Sri Lankan
ranking of ED. For example, Indian Pitta, which
ranks 3rd in the local ranking, is 10th when these
10 species are arranged according to their
global rankings. Osprey in the other hand ranks
8th in the local list, is 1st when it is taken in the
order of global rankings. The reason for this is
in the local context, Indian Pitta is a monotypic
genus, so its ED goes up when only the birds of
Sri Lanka are considered, but when consider the
global phylogeny, there are 30 species of pittas
(Fig. 02). In the case of Osprey, it is a
monotypic genus in both local (Fig. 02) and
global contexts. So the ED of Osprey is high
locally and globally. As described previously,
the EDGE score of a species depends on both
the ED and the IUCN red list status of that
species (Isaac et al., 2007). Therefore, to have a
high EDGE score, the species should be an
isolated node in the phylogenetic tree with a
globally threatened status. Our results showed
that the Serendib Scops-owl has the highest
EDGE score (5.26). Serendib Scops-owl
however has a relatively low ED (23.00) but it is
an endangered endemic. Ceylon Frogmouth
topped the list for highest ED, but it is 13th
species in the EDGE list. Six species out of the
10 top ranked evolutionary distinct endangered
lineages, are endemic to Sri Lanka (Table 03).
However the ED of all these endemic species
are relatively low.
The order of ranking is again different when
considering the National Red List and Global
Red List for the calculations of EDGE score.
The Serendib Scops-owl which is 1st when
using Global Red List is the 23rd when using
National Red List, while Slaty-legged Crake
(Rallina eurizonoides) is 66th when using
Global Red List but is 1st when National Red
List is used. We stick to Global IUCN rankings
because the National Red List tend to
overemphasise several small populations of
globally widespread species such as
Slaty-legged Crake, Yellow-legged Green
Pigeon (Treron phoenicopterus) and Indian
Courser (Cursorius coromandelicus), all of
them are Critically Endangered in the Local
IUCN list due to small population size. On the
other hand, some of the range restricted Sri
Lankan endemics are lower in the National Red
List’s vulnerability index even though they are
range-restricted endangered species in the
IUCN Global list.
The evolutionary past of a clade can be
traced through phylogenetic trees. Such
phylogenetic trees can also be used to measure
the amount of evolutionary history captured by
its member species. Evolutionary Distinctness
(ED) and Evolutionary Distinct and Globally
Endangered Score (EDGE) are two such vital
parameters that could elucidate the
phylogenetic history captured in member
species. Using the total species recorded in
IBAs of Sri Lanka we constructed a
phylogenetic tree to evaluate the ED and EDGE
scores of Sri Lankan Birds. Ceylon Frogmouth
is the most evolutionary distinct (ED) species in
the island, while Serendib Scops-owl is the
most evolutionary distinct endangered lineage
(EDGE). Members of order Charadriiformes in
general have the lowest ED values.
ACKNOWLEDGEMENT
We are grateful to Dr. Praveen Karanth and
the members of the Evolving Phylo - Lab at the
Indian Institute of Science and Dr. Arne Mooers
at the Simon Fraser University, Canada for
assistance with the phylogenetic tools. The
Field Ornithology Group of Sri Lanka provided
the IBA database for this study. Department of
Zoology and Environment Sciences, University
of Colombo provided funding for DA and SS
for this study. We also thank Mr. Hasitha Perera
and Dr. Gehan Rajeev for providing bird images
and Dr. Nishanthi Perera and Dr. Hashendra
Kathriarrachchi for commenting on the manu-
script.
Rasmussen, P. C. and J. C. Anderton, (2005).
Birds of South Asia: The Ripley Guide,
Lynx Edicion, Barcelona, Spain.
Redding, D.W., K. Hartmann, A. Mimoto, D.
Bokal, M. Devos, and A.O. Mooers,
(2008). Evolutionarily distinctive
species often capture more phylogenetic
diversity than expected. J. Theor. Biol.
(251):606–615.
Ripley, S. D. (1949). Avian relics and double
invasions in peninsular India and
Ceylon. Evolution, (3):150-159.
Ripley, S. D. and B. M. Beehler (1990). Patterns
of speciation in Indian birds. Journal of
Biogeography (17):639-648.
Vellend, M., W. K. Cornwell, K.
Magnuson-Ford, and A. Ø. Mooers,
(2011). Measuring phylogenetic
biodiversity. Biological diversity:
frontiers in measurement and
assessment. Oxford University Press,
Oxford, UK, 194-207.
Received Date : 21 April 2017
Accepted Date : 28 April 2017
010May, 2017] EVOLUTIONARY DISTINCTIVENESS OF SRI LANKAN AVIFAUNA
REFERENCES
Bossuyt, F., and M. Meegaskumbura, et. al.,
(2004). Local endemism within the
Western Ghats-Sri Lanka biodiversity
hotspot. Science, 306(5695): 479–81.
Brusatte, S. L., J. K. O’Connor, and E. D. Jarvis,
(2015). The origin and diversification of
birds. Current Biology, 25(19):
R888-R898.
Butchart, S. H. M., A. J. Stattersfield, L. A.
Bennun, S. M. Shutes, H. R. Akc, J. E.
M. Baillie, and G. M. Mace, (2010).
Measuring Global Trends in the Status
of Biodiversity : Red List Indices for
Birds, 2(12): doi.org/10.1371/journal.
pbio.0020383.
Drummond, A. J., S. Y. W. Ho, N. Rawlence,
and A. Rambaut, (2007). A rough guide
to BEAST 1(4): University of Auckland,
Auckland, New Zealand.
Fernando S.P., D.E. Irwin, and S.S.
Seneviratne, 2016. Phenotypic and
genetic analysis support distinct species
status of the Red-backed Woodpecker
(Lesser Sri Lanka Flameback:
Dinopium psarodes) of Sri Lanka Auk:
Ornithological Advance 133:497-511
Hackett, S. J., R. T. Kimball, S. Reddy, R. C.
Bowie, E. L. Braun, M. J. Braun, and C.
J. Huddleston, (2008). A phylogenomic
study of birds reveals their evolutionary
history. Science, 320(5884):1763-
1768.
Isaac, N. J. B., S. T. Turvey, B. Collen, C.
Waterma, and J. E. M. Baillie, (2007).
Mammals on the EDGE: Conservation
Priorities Based on Threat and
Phylogeny, (3):Doi.org/10.1371/
journal.pone.0000296.
Jetz, W., G. H. Thomas, J. B. Joy, K. Hartmann,
and A. O. Mooers, (2012). The global
diversity of birds in space and time.
Nature, 491(7424):444-448.
Jetz, W., G. H. Thomas, J. B. Joy, D. W.
Redding, K. Hartmann, and A. O.
Mooers, (2014). Global Distribution
and Conservation of Evolutionary
Distinctness in Birds. Current Biology,
24(9):919–930. Doi.org/10.1016/ j.cub.
2014.03.011.
MacArthur, R. H. and E. O. Wilson, (1967). The
Theory of Island Biogeography. N.J.
Princeton, Princeton University Press.
National Red List of Sri Lanka 2012. World
Conservation Union (IUCN) in Sri
Lanka and the Ministry of Environment
and Natural Resources, Government of
Sri Lanka.
Nee, S., and R. M. May, (1997). Extinction and
the Loss of Evolutionary History.
Science, 278(5338):692–694. doi.org/
10.1126/science.278.5338.692.
Rasmussen, P. C. and J. C. Anderton, (2005).
Birds of South Asia: The Ripley Guide,
Lynx Edicion, Barcelona, Spain.
Redding, D.W., K. Hartmann, A. Mimoto, D.
Bokal, M. Devos, and A.O. Mooers,
(2008). Evolutionarily distinctive
species often capture more phylogenetic
diversity than expected. J. Theor. Biol.
(251):606–615.
Ripley, S. D. (1949). Avian relics and double
invasions in peninsular India and
Ceylon. Evolution, (3):150-159.
Ripley, S. D. and B. M. Beehler (1990). Patterns
of speciation in Indian birds. Journal of
Biogeography (17):639-648.
Vellend, M., W. K. Cornwell, K.
Magnuson-Ford, and A. Ø. Mooers,
(2011). Measuring phylogenetic
biodiversity. Biological diversity:
frontiers in measurement and
assessment. Oxford University Press,
Oxford, UK, 194-207.
Received Date : 21 April 2017
Accepted Date : 28 April 2017
... This species is mostly found in dense tropical forests and is thus considered a forest specialist. In Sri Lanka, it frequents southwestern tropical lowland rainforests (jayarathna, 2004;Kotagama & Ratnavira, 2010) and is considered the most evolutionary distinct bird (Abeyrama & Seneviratne, 2017). Occasionally, the frogmouth has also been documented in secondary and analogue forests (Bambaradeniya et al., 2003;Gamage et al., 2006;Dissanayake et al., 2014;Gabadage et al., 2015). ...
... pesticide use is intensifying, even in ruderal landscapes of Sri Lanka (Gunatilleke et al., 2017), which can reduce frogmouth prey abundance while predisposing them to agrochemical bioaccumulation. The Sri Lanka Frogmouth is the only member of the podargid lineage in Sri Lanka and is considered evolutionary unique among Sri Lankan avifauna (Abeyrama & Seneviratne, 2017), which underscores its conservation significance. Given its discontinuous distribution across a wider geographic range across multiple bioclimatic zones, we propose that the Sri Lanka Frogmouth be considered "regionally common but locally rare" or a "wideranging species with fragmented distribution" (Cf. ...
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The rapid destruction of the planet's biodiversity has prompted the nations of the world to set a target of achieving a significant reduction in the rate of loss of biodiversity by 2010. However, we do not yet have an adequate way of monitoring progress towards achieving this target. Here we present a method for producing indices based on the IUCN Red List to chart the overall threat status (projected relative extinction risk) of all the world's bird species from 1988 to 2004. Red List Indices (RLIs) are based on the number of species in each Red List category, and on the number changing categories between assessments as a result of genuine improvement or deterioration in status. The RLI for all bird species shows that their overall threat status has continued to deteriorate since 1988. Disaggregated indices show that deteriorations have occurred worldwide and in all major ecosystems, but with particularly steep declines in the indices for Indo-Malayan birds (driven by intensifying deforestation of the Sundaic lowlands) and for albatrosses and petrels (driven by incidental mortality in commercial longline fisheries). RLIs complement indicators based on species population trends and habitat extent for quantifying global trends in the status of biodiversity. Their main weaknesses are that the resolution of status changes is fairly coarse and that delays may occur before some status changes are detected. Their greatest strength is that they are based on information from nearly all species in a taxonomic group worldwide, rather than a potentially biased subset. At present, suitable data are only available for birds, but indices for other taxonomic groups are in development, as is a sampled index based on a stratified sample from all major taxonomic groups.
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We analysed the distributions of fifty-eight avian sister-species pairs from the Indian region in order to determine the concordance of inter-species range boundaries with physiographic barriers in the region, and to delineate the degree to which the pattern of distribution of the species-pairs accords with the predictions of four models of geographic speciation. Fifty species-pairs exhibited range boundaries that were associated with one or more major environmental features of the Indian subcontinent: major river system (twenty), salt water passage (fifteen), mountain chain (ten), break in mountain chair (four), plains/mountain discontinuity (six). Among our Indian sample of sister-species pairs, we found examples showing a favourable fit to each of the four speciation models: dispersal model (twenty-five examples), vicariance model (eleven), refugial model (eight), parapatric model (six); eight examples could not be assigned with certainty. Support for the rarely-considered parapatric model is consistent enough to warrant further investigation of its possible importance in vertebrate speciation.
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Current global patterns of biodiversity result from processes that operate over both space and time and thus require an integrated macroecological and macroevolutionary perspective. Molecular time trees have advanced our understanding of the tempo and mode of diversification and have identified remarkable adaptive radiations across the tree of life. However, incomplete joint phylogenetic and geographic sampling has limited broad-scale inference. Thus, the relative prevalence of rapid radiations and the importance of their geographic settings in shaping global biodiversity patterns remain unclear. Here we present, analyse and map the first complete dated phylogeny of all 9,993 extant species of birds, a widely studied group showing many unique adaptations. We find that birds have undergone a strong increase in diversification rate from about 50 million years ago to the near present. This acceleration is due to a number of significant rate increases, both within songbirds and within other young and mostly temperate radiations including the waterfowl, gulls and woodpeckers. Importantly, species characterized with very high past diversification rates are interspersed throughout the avian tree and across geographic space. Geographically, the major differences in diversification rates are hemispheric rather than latitudinal, with bird assemblages in Asia, North America and southern South America containing a disproportionate number of species from recent rapid radiations. The contribution of rapidly radiating lineages to both temporal diversification dynamics and spatial distributions of species diversity illustrates the benefits of an inclusive geographical and taxonomical perspective. Overall, whereas constituent clades may exhibit slowdowns, the adaptive zone into which modern birds have diversified since the Cretaceous may still offer opportunities for diversification.