Conservation Genetics of the African Lion

Abstract

Recently a consortium of research-ers has published their findings on genetic research on lions, which revealed a remarkable difference between lions in West and Central Africa and lions in East and southern Africa in the Journal of Biogeopgra-phy (Bertola et al, 2011). A pattern is described that deviates from current taxonomy, which illustrates the value of genetic data when working in the field of species conservation. A basic principle in conservation biology is that we should aim to conserve species as dynamic entities that are able to cope with environ-mental change. This implies that it is essential that the maximum of the genetic diversity within a species is conserved, thereby preserving the evolutionary potential of the species. In the case of the lion, it has become more and more clear that present day taxonomy, only distinguishing the African lion Panthera leo leo and the Asiatic lion Panthera leo persica, does not sufficiently reflect the different genetic lineages within the species. Following taxonomy and considering the African lion as one homogenous group will lead to inadequate man-agement of the species as a whole. Genetically distinct populations may be mixed and important genetic information will be lost. Phylogenetic and biogeographic data are of utmost importance to define management strategies for species conservation. These data do not only give informa-tion on the present day situation and possible (genetic) threats these populations may be facing, but also on the evolutionary history that has shaped the current genetic make up. Thereby it provides a rational basis for prioritising populations for conserva-tion effort, given the fact that it is aimed to minimize the loss of genetic diversity and preserve genetically distinct lineages.

Full text

Conservation Genetics
of the African Lion
Laura Bertola, Klaas Vrieling and Hans de Iongh – CML1 & IBL2, Leiden University
Recently a consortium of research-
ers has published their ndings on
genetic research on lions, which
revealed a remarkable dierence
between lions in West and Central
Africa and lions in East and southern
Africa in the Journal of Biogeopgra-
phy (Bertola et al, 2011). A pattern is
described that deviates from current
taxonomy, which illustrates the value
of genetic data when working in the
eld of species conservation.
A basic principle in conservation
biology is that we should aim to
conserve species as dynamic entities
that are able to cope with environ-
mental change. This implies that it is
essential that the maximum of the
genetic diversity within a species is
conserved, thereby preserving the
evolutionary potential of the species.
In the case of the lion, it has become
more and more clear that present day
taxonomy, only distinguishing the
African lion Panthera leo leo and the
Asiatic lion Panthera leo persica, does
not suciently reect the dierent
genetic lineages within the species.
Following taxonomy and considering
the African lion as one homogenous
group will lead to inadequate man-
agement of the species as a whole.
Genetically distinct populations may
be mixed and important genetic
information will be lost. Phylogenetic
and biogeographic data are of utmost
importance to dene management
strategies for species conservation.
These data do not only give informa-
tion on the present day situation
and possible (genetic) threats these
populations may be facing, but also
on the evolutionary history that has
shaped the current genetic make up.
Thereby it provides a rational basis for
prioritising populations for conserva-
tion eort, given the fact that it is
aimed to minimize the loss of genetic
diversity and preserve genetically
distinct lineages.
In the history of lion conservation,
there was not much concern for
the status of the African lion until
recently. This is also reected by the
lack of an international studbook
for the African lion. For the Asiatic
subspecies, an international studbook
was set up in 1971, in combination
with regional conservation breed-
ing programs operated by AZA and
EAZA. The subspecies of the Afri-
can lion, was long considered to be
abundant and wide-ranging with no
direct threats that would ask for radi-
cal conservation measures. However,
now it has been recognized that both
lion numbers and lion range are at
an alarming decline. Most research-
ers agree on an estimate of less than
40,000 free ranging African lions,
representing a decline of almost
50% (three lion generations) when
comparing this gure to a modelled
75,800 lions in 1980. The situation in
West and Central Africa looks even
more gloomy, where the lion popula-
tions have shown the steepest de-
cline. In this region the lion is already
qualied as regionally endangered,
according to IUCN criteria. It was
concluded that only 10% of the con-
tinental population is located in West
and Central Africa, but even this may
be a positive estimate. According to
a recent survey in 15 of the 20 dened
Lion Conservation Units in West and
Central Africa, things look even worse,
as researchers were only able to
reconrm the presence of lions in two
of the studied areas. On top of that,
lion populations in West and Central
Africa are generally small and isolated
and lions almost completely disap-
peared from non-protected areas.
Our data show that, from a genetics
point of view, there is a remarkable
dierence between lions from West
and Central Africa and lions from East
and southern Africa. These data also
show an unexpected close relation-
ship between lions from West and
Central Africa and lions from the
Asiatic subspecies. Morphological
and ecological data also suggest that
lions from West and Central Africa are
dierent from the other African lions:
individuals tend to be smaller, live in
smaller prides and prefer smaller prey
than lions in East and southern Africa.
The bellyfold, which is very charac-
teristic for Asiatic lions is also present
in an exceptionally high frequency in
lions in West and Central Africa.
In addition to the described relation-
ship between the lion metapopula-
tions, West and Central African lions
also show a lower genetic diversity
within the region, compared to the
other African lions. Because the
analyzed dierences in the DNA are
shared by more populations in West
and Central Africa, it is not likely that
the loss of genetic diversity was a re-
sult of local inbreeding. More likely is
the scenario in which this clade of li-
ons represents an evolutionary young
group, arisen from relatively recent
(re-) colonization of the area. This
1 Institute of Environmental Sciences (CML),
Leiden University
2 Institute of Biology Leiden (IBL),
Leiden University
…present day
taxonomy does
not suciently
reect the dierent
genetic lineages
within the species…
2WAZA news 3/11

»
part of Africa had a dierent climato-
logical history compared to the rest
of the continent and was character-
ized by hyper arid condition in the
Late Pleistocene (40-18 thousand
years ago). It is hypothesized that
lions went locally extinct, possibly
following the extinction of prey spe-
cies, and that this region was recolo-
nized when conditions changed to
a more favourable climate again 15-11
thousand years ago. In this scenario
recolonization took place from areas
in close geographic proximity to India,
hereby explaining the close genetic
relationship to the Asiatic subspecies.
Data from other mammal species
show similar patterns in which popu-
lations in West and Central Africa
are distinct from populations in East
and southern Africa. It is likely that
the climatological history has also
inuenced other species leading to
the observed dichotomy. In addition
to the inuence of climatological
changes, also current natural struc-
tures that form barriers for further
dispersal of the species (e.g. the
African rain forest or the Rift valley in
East Africa) may have inuenced the
genetic pattern we observe.
The described pattern of distinct
genetic lineages within the subspe-
cies of the African lion should not
only have implications for man-
agement of wild populations, but
also for breeding of captive stocks.
Despite the lack of a studbook for
the African lion, within this group at
least seven “subspecies” are being
distinguished on ISIS (P. l. azandica,
P. l. bleyenberghi, P. l. krugeri, P. l. leo,
P. l. massaica, P. l. senegalensis, P. l.
somaliensis), accounting for less then
20% of the almost 2000 registered
lions (15% of registered lions belongs
to the Asiatic subspecies, the origin
of the majority of registered individu-
als remains unknown, according to
ISIS). However, how should we deal
with so called subspecies, especially
when numbers within subspecies are
already that low? In several zoos lions
from dierent African “subspecies”
are held together. Information on the
origin of these lions, or their free-
ranging ancestors, is often question-
able or incomplete and it would not
be sensible to interpret the proposed
subspecies name as a reection of ge-
netic heritage without doing further
research. Several cases are known in
which individuals have been assigned
to a certain subspecies, but details
on the breeding history revealed that
it was not possible to be sure of the
pure line within these individuals
because of past hybridization events.
Maybe a new inventory of lions in all
zoos associated with WAZA could
help clarifying the picture on the
(genetic) diversity of lions currently
held in captivity. Breeding animals in
combination with (in most cases very
probable) hybridization of several
genetic lineages, is likely to distort
the picture somewhat. Analysis of
a large enough number of genetic
markers should still make it possible
to get better insight into genetic
diversity and heritage of captive
lions. This comes more and more into
reach with upcoming next genera-
tion sequencing techniques, by which
a new magnitude of datapoints (tens
of thousands variable positions in the
DNA) can be analyzed cost-eective-
ly. This type of analysis will also give
insight in possible genetic risks, like
inbreeding, which are especially well
known from captive-bred animals.
Application of these data will make it
possible to construct a management
plan with a balance of genetic diver-
sity on two levels: a greater genetic
diversity is maintained when distinct
genetic lineages are managed as such,
but these units should still be large
enough to avoid inbreeding.
Map with present day lion distribution
and the colours indicating the identified
clades: West and Central Africa (yellow),
East and southern Africa (pink), India (green).
Triangles, dots and squares indicate the location
of the samples and what genetic markers
were used for phylogenetic analysis.
3
WAZA news 3/11

»
Zoos have made a considerable
shift from simple display of exotic
animals to major players in the eld
of species conservation. A common
eort should be made to reect the
diversity of the free ranging popula-
tions also in captive stocks, although
limitations like the number of partici-
pating institutions should be taken
into account. Remarkable is that only
4% of all lions registered in CITES are
supposed to be from a “subspecies”
that contains West or Central African
haplotypes (P. l. senegalensis and
P. l. leo). In the light of the recently
described phylogeographic pattern,
there would be strong arguments to
treat this group with extra care. Be-
cause of the alarming situation of the
lion in Africa, and especially the West
and Central African region, it would
be irresponsible to suggest that the
zoo population should get an inux
from free-ranging lions from this
region. However, a previous genetic
study by Barnett et al. has illustrated
that lions that were assumed to be
from the Barbary subspecies P. leo
leo contained a haplotype that was
found in Central Africa. Even though
these particular animals may not be
completely “pure”, they may still
be able to full the role in maintain-
ing this genetic line within the zoo
population.
When working on species conserva-
tion choices on what to preserve
are inevitable. The eld of conser-
vation genetics can contribute to
this by highlighting populations or
meta-populations based on a unique
evolutionary history, which has led to
a unique genetic make up. The use of
new cost-eective high throughput
genotyping technique that enable to
analyze thousands of markers at once
will be the main leading tools to pre-
serve and recognize genetic entities.
Zoos can add to this by documenting
the genetic lineages and and assesing
the genetic variation in their stocks
and starting up a studbook for African
lions. In the case of the lion we see
a pattern deviating from current tax-
onomy, but exactly this pattern may
be essential to preserve.
Full reference:
Bertola, L. D., Van Hooft, W. F.,
Vrieling, K., Uit de Weerd, D. R.,
York, D. S., Bauer, H., Prins, H. H. T.,
Funston, P. J., Udo de Haes, H. A.,
Leirs, H., Van Haeringen, W. A.,
Sogbohossou, E., Tumenta, P. N.,
De Iongh, H. H. (2011) Genetic
diversity, evolutionary history
and implications for conservation
of the lion (Panthera leo) in West
and Central Africa. Journal
of Biogeography. DOI:
10.1111/j.1365-2699.2011.02500.x
Contact:
laura.bertola@gmail.com
Lion with GPS collar from WAZA National Park, Cameroon (West – Central Africa clade),
© Ralph Buij
the characteristic belly fold is clearly visible.
4WAZA news 3/11