Content uploaded by Allan D McDevitt
Author content
All content in this area was uploaded by Allan D McDevitt
Content may be subject to copyright.
DEER 23
U
nderstanding the origins of particular red deer
populations is an important consideration
when assessing their conservation value.
Nowhere has the origins of red deer been a
more controversial topic than in Ireland, with
claims of there being ‘native’ Irish herds in various parts
of the island. However, these claims have never been
backed-up with any concrete scientific evidence to speak
of. Because of this discrepancy between hearsay and actual
evidence, we embarked on a study in 2008 to finally
look at the origins of red deer in Ireland in more detail1.
This required a multi-disciplinary approach to address
this complex issue, combining expertise from scientists
with individual backgrounds in genetics, ecology,
zooarchaeology, morphometrics and perhaps most
importantly, red deer.
The origins of red deer in Ireland
Red deer have an extensive fossil record in Ireland, being
present before the Last Glacial Maximum (26,000–19,000
years ago), after which they vanished before reappearing
along with other ungulates such as reindeer and the giant
deer before the Younger Dryas glaciation (c. 12,000 years
ago). Once again, there was no evidence of them after
this glaciation and they do not reappear in the fossil
record until the Neolithic period (c. 6000 - 4500 years
ago). This information was based on only six dated
bone fragments2and many more bone fragments exist
of red deer in Ireland. In order to confirm the existence
of this gap (absence between 26,000–13,000 and
between 12,000–5,000 years ago) in the fossil record
for red deer in Ireland, we subjected a total of 17 new
bone fragments to radiocarbon dating. These new dates
confirmed the fossil record gaps, with the majority
of newly dated bones from after the beginning of the
Neolithic period1. A comprehensive review of the
scientific literature and unpublished reports of the
palaeontological and zooarchaeological Irish sites
suggested the absence of the species during the Mesolithic
period (c. 9,500 - 6,000 years ago).
These considerable gaps clearly cast doubt on the
continued presence of red deer in Ireland throughout
the last 30,000 years. Bone fragments become more
prominent from the Neolithic period onwards but
given that we know that red deer have been brought
to Ireland on numerous occasions during the last 200
years in particular, how do we know if any red deer in
Ireland are actually descendents from those ancient red
deer? To do this, we turned to DNA. Our ancestral
history is contained in our DNA and this allows us
to trace back modern Irish red deer to their ancestors
and potential source populations. We use a stretch of
Ireland’s Ancient Deer
Dr. Allan McDevitt and Dr. Ruth Carden examine the mystery
of Ireland’s oldest red deer population
© BLAINE HARRINGTON III / ALAMY
Killarney National Park:
Home of the only true Irish population of red deer?
24 DEER
DNA from the mitochondrion (the
energy producing organelle in the cell),
which is transferred from the mother
to her offspring with no mixing from
the father. This allows us to trace back
ancestral history along a single genetic
line. Given advances in genetic
methodology, we can now extract DNA
not just from modern individuals, but
from ancient bone fragments thousands
of years old. With these methodologies
available to us, we compared DNA from
modern red deer from Ireland, Britain,
continental Europe and New Zealand to
ancient Irish individuals from the last
30,000 years. This revealed interesting
results even before comparing the various
red deer populations. Three bone
fragments from approximately 30,000
years ago identified from morphology
as red deer turned out to be reindeer
from our DNA results.
Figure 1
Figure 1 shows a phylogenetic network of
almost 1,400 red deer collected through-
out the British Isles, continental Europe
and New Zealand, and the ancient Irish
red deer. These include 172 sequences
collected by ourselves, the remainder
having been obtained from GenBank as
a result of studies by other researchers.
Each of the circles represents a unique
DNA type, with the size of the circles
proportional to the number of red deer
that share that DNA type. These circles
are then divided into the number of red
deer from each region (colour-coded)
that share that DNA type. Individuals
which share the same DNA type obviously
have a shared ancestry and the more closely
connected these DNA types are to each
other, the more closely related they are
also. Take the circle labelled ‘W’ in the
top right hand corner for instance.
Individuals from Rum (light blue),
Sardinia (orange), Ireland (green) and
western Europe (red) share this DNA
type and this DNA type is closely related
to other DNA types found in Sardinia.
In almost all cases, you will see that
modern red deer from Ireland share
DNA with Scottish individuals.
Several interesting relationships are
highlighted to demonstrate the power
of using DNA to trace deer translocations,
using historical documents to confirm
them. We know for instance that red
deer were transported from Scotland
to Co. Donegal in the late 1800s and we
see that the Donegal deer share their
DNA with Scottish deer (circles labelled
‘D’). Another example shows the DNA
type labelled ‘G’, which is red deer from
Screebe Estate in Galway in the west of
Ireland. These individuals were brought
from Warnham Park in the 1980s, and
this English park in turn had previously
imported red deer from the European
continent. This is why we see this DNA
type carried by Irish, English and western
European individuals. Finally, we have
the ‘W’ example mentioned earlier. We
know that red deer were introduced to
Wicklow in eastern Ireland from the
Scottish islands in the 1800s and this
relationship is again reflected in their
DNA. So we can appreciate the use of
genetic techniques in helping to decipher
the origin of red deer populations.
Having historical information in
conjunction with genetic data is valuable,
but in many cases, this information is
lacking. One herd in particular in Ireland
has a paucity of historical records, the
Killarney herd in Co. Kerry in the south-
west of Ireland with a limited number of
known introductions taking place from
other regions in Ireland and Scotland.
Killarney has acted a source for other
Irish populations, sending deer to Donegal
and the west of Ireland and several of the
Scottish islands. This population has
always laid claim to being Ireland’s ‘native’
red deer population. If we look at the
network, we see that the Killarney red deer
(brown) have two DNA types. The DNA
type with most individuals of these two
has individuals from Killarney, Donegal
Figure 1
Red deer in Killarney National Park
© DEADLYPHOTO.COM / ALAMY
(not shown), the west of Ireland, mainland
Scotland, Rum and New Zealand.
Importantly, you will also see the ancient
Irish red deer (yellow) sharing this DNA.
The sharing of DNA between Killarney
and the other Irish regions can be
explained by the translocations explained
above. The inclusion of New Zealand red
deer here shows known translocations
from Scotland to New Zealand in the
early part of the 20th century. What
is particularly interesting is the link
between the Killarney red deer, Scotland
and the ancient individuals. Not only
is this DNA type shared, but we also see
another DNA type shared exclusively
between modern red deer from Killarney
and an ancient one. In addition, the four
other ancient Irish red deer are closely
related to the Killarney red deer. This
clearly shows a link between the Killarney
red deer specifically and the red deer
present in Ireland during the Neolithic.
The additional link with Scottish red
deer gives us an indication that these
Irish ancient red deer were brought from
Britain and the modern Killarney reds
are the direct descendents of these
animals. Although these molecular data
show a relationship between ancient Irish
individuals, Killarney and Scotland, there
is a need to go further, however, to rule
out the possibility that the Killarney red
deer are a more recent introduction from
Scotland and merely share DNA with the
ancient Irish red deer by chance.
Figure 2
In light of the results obtained from
the genetic analyses and historical
introductions, craniometric analyses of
the shape and the size of the female adult
skulls were conducted on three red deer
‘populations’. These populations were
from Killarney, Donegal and Scotland.
These specific populations were chosen
to examine if the proposed ‘ancient’ Irish
population (Killarney) was distinct from
both a ‘modern’ Irish population
(Donegal) and their proposed source
population (Scotland). A total of 33
skull measurements were taken, which
was then reduced down to the eight
measurements that explained most of the
variation between the three populations.
Results from the Principal Component
Analysis (PCA) indicated that the
Scottish red deer were more similar to
those from Donegal, while both the
Scotland and Donegal deer were
significantly different from the Killarney
deer. These findings are compatible with
the molecular analyses and the historical
records, where Donegal red deer were
introduced from amongst other locations,
from Scottish herds, only 120 years ago.
Therefore, they are very similar to the
Scottish red deer (completely overlapping
with them). However, the original
introduction of red deer to Ireland is
thought to have occurred at least 4,000
years ago, which would allow sufficient
shape and size differences to evolve over
these thousands of years. This is why we
see the Killarney population overlapping
with the Scottish and Donegal deer to a
certain extent but also showing enough
separation to suggest a long term isolation
from the original Scottish stock.
Conservation and Management
Implications
The results of this study have important
implications for the conservation and
management status of the Killarney herd.
In 2009, the National Parks and Wildlife
Service in the Republic of Ireland and
The Environmental Agency in Northern
Ireland jointly published the Red List of
Terrestrial Mammals in Ireland3. In this
publication, the authors assessed the
conservation status of mammals that
were present in Ireland prior to 1500 AD
(species described as naturalised in, or
native to, Ireland). Red deer was listed as
‘least concern’. However, only one red
deer population in Ireland actually fits
this arbitrary criterion of being native
or naturalised: the Killarney herd. Given
that the classification of ‘Irishness’ in this
Red List has little scientific meaning,
does our finding that the Killarney herd
is Ireland’s only ancient population of
red deer actually mean something in
terms of preserving its unique Irish
heritage?
We believe that it does for the following
reason. It is becoming clear that Ireland
has few mammals that have been persisted
through the two major ice ages of the last
25,000 years. In fact, there still remain
outstanding questions for those mammals
that have been proposed to have survived
the major glaciations in Ireland. Our red
deer study, along with work on the pygmy
shrew4has suggested that Neolithic
people from Britain might have played
a pivotal role in bringing wild mammals
to Ireland, either deliberately or
accidentally. Therefore, we believe that
those species that arrived with ancient
humans and have persisted since then
have a legitimate claim to be called an
‘Irish’ species/population. This would
make the Killarney red deer the only
true Irish population still in existence
on the island.
Red deer had a special and cultural
significance for ancient peoples, so it
is also about protecting these deer and
protecting our own Irish heritage. This
would make the preservation of this
population a priority within an Irish
context. It is important to note the ‘Irish
context’ here because the Killarney
population carries no great international
significance based on its history: they
are red deer transported to Ireland from
Britain approximately 5,000 years ago.
However, it should be the responsibility
of the Irish authorities to protect the
heritage of what may be our only ancient
population, something that would
ultimately have the same end result as
international protection. In order to
achieve this, we discuss several important
issues below that need to be monitored.
The population of red deer within
Killarney National Park has remained
historically low,5with numbers fluctuating
between 1,000 down to as low as 100
individuals during the last 50 years. This
herd is geographically isolated from herds
DEER 25
Figure 2
in the rest of the island6and
evidence from molecular data
indicates that it forms its own
genetic cluster, with no or very
limited natural gene flow with
other herds7. Whilst this helps to
protect the genetic purity of this
herd, it also leads to potential
problems associated with small
populations. Levels of genetic
diversity are very low in this herd
and are at levels associated with
the most threatened red deer
population in northern Africa,
the Barbary red deer7. Even within
Killarney National Park, there is
subdivision of the herd into two genetic
groups based on a preliminary study,
with individuals in the western mountains
(where the number of individuals is
particularly low) separated from those
on the eastern side of the Park5.
Low population size can lead to
inbreeding which can have potential
negative effects on the population. This
can lead to increased susceptibility to
disease and detrimental physical effects.
An isolated population in Germany
for instance has shown several cases
of brachygnathy (shortened lower jaw),
which is commonly associated with
inbreeding depression8. Human land-
use along the borders of the Park and
conservation efforts associated with
woodland habitats lead to some selective
culling but it should certainly be a
priority to keep red deer numbers on
the upper range of their historical
numbers (600–1,000 individuals) to
avoid such inbreeding effects occurring
in this ancient population.
Small population size and subsequent
inbreeding effects are not the only
potential threat to the Killarney herd.
Hybridisation with sika is a genuine
concern. A study undertaken by ourselves
concurrently with the Irish origins
study used genetic markers to look at
hybridisation between red deer and
sika in regions where their ranges overlap
in Ireland7. Thankfully, no evidence of
hybridisation was found in Killarney
but hybridisation was confirmed to be
widespread in Co. Wicklow in the east
of the island (we also reported that
hybridisation potentially occurred in
the west of Ireland but a more stringent
re-analysis of this data suggests that this
may not be the case). This is particularly
interesting because the two species have
overlapped in each of these regions for a
similar length of time (around 150 years)
yet hybridisation only occurs in Wicklow.
A similar situation was found in Scotland
with one area showing high levels of
hybridisation and a virtual absence of it
elsewhere9. Although hybridisation is still
a rare event in the wild, the danger is
that once it occurs, it can spread rapidly
in a population. While this might not
occur in the Killarney population, both
red deer and sika from Wicklow (and
undoubtedly their hybrids also) have
been spreading south and westwards over
the last 30 years and the sika range has
been expanding considerably in the
southwest, much more so than the red
deer range6. If this hybrid expansion
from the east comes into contact with
the southwest expansion, then in all
likelihood, this may represent the biggest
threat to the genetic integrity of the
Killarney red deer. It goes without saying
that this potential hybrid expansion from
the east should be continually monitored.
In fact, a more detailed look at hybrid-
isation between the two species in
Ireland is currently ongoing in the
University of Edinburgh but we would
hope that continuous monitoring would
continue across the south of Ireland.
Not only would this contribute to
applied managment of the situation but
it would also hopefully provide insights
into the hybridisation process between
the two species.
In summary, this multi-disciplinary
study has identified the multiple
introductions of red deer to Ireland
during the last 5,000 years. Red deer
had cultural significance in
ancient times, leading Neolithic
peoples to bring red deer across
the Irish Sea from Britain to
Ireland. Many introductions of
red deer have occurred in the last
200 years or so but the herd that
currently resides in Killarney
National Park and its
surrounding lands represents the
direct descendents of those ancient
red deer and are what we can
consider as true Irish red deer.
We firmly believe that every
effort should be made to protect the
genetic heritage of this unique Irish
herd amid concerns about potential
inbreeding effects
and the threat of
hybridisation with sika.
26 DEER
REFERENCES
1. Carden, R.F., McDevitt, A.D., Zachos, F.E.,
Woodman, P.C., Rose, H., Monaghan, N.T.,
O’Toole, P., Campana, M.G., Bradley, D.G. &
Edwards, C.J. (2012) Phylogeographic, ancient
DNA, fossil and morphometric analyses reveal
ancient and modern introductions of a large
mammal: the complex case of red deer (Cervus
elaphus) in Ireland. Quaternary Science Reviews,
doi: 10.1016/j.quascirev. 2012.02.012.
2. Woodman, P.C., McCarthy, M. & Monaghan, N.
(1997) The Irish Quaternary fauna project.
Quaternary Science Reviews, 16, 129-159.
3. Marnell, F., Kingston, N. & Looney, D. (2009) Ireland
Red List No. 3: Terrestrial Mammals, National
Parks and Wildlife Service, Department of the
Environment, Heritage and Local Government,
Dublin, Ireland.
4. McDevitt, A.D., Vega, R., Rambau, R.V., Yannic, G.,
Herman, J.S., Hayden, T.J. & Searle, J.B. (2011)
Colonization of Ireland: revisiting ‘the pygmy shrew
syndrome’ using mitochondrial, Y chromosomal
and microsatellite markers. Heredity, 107, 548-557.
5. McDevitt, A.D., O’Toole, P., Edwards, C.J. &
Carden, R.F. (in press) Landscape genetics of red
deer (Cervus elaphus, Linnaeus 1758) in Killarney
National Park, County Kerry. Irish Naturalists’
Journal.
6. Carden, R.F., Carlin, C.M., Marnell, F., McElholm,
D., Hetherington, J. & Gammell, M.P. (2011)
Distribution and range expansion of deer in Ireland.
Mammal Review, 41, 313-325.
7. McDevitt, A.D., Edwards, C.J., O’Toole, P.,
O’Sullivan, P., O’Reilly, C. & Carden, R.F. (2009)
Genetic structure of, and hybridisation between,
red (Cervus elaphus) and sika (Cervus nippon) deer
in Ireland. Mammalian Biology, 74, 263-273.
8. Zachos, F.E., Althoff, C., Steynitz, Y.V., Eckert, I. &
Hartl, G.B. (2007) Genetic analysis of an isolated
red deer (Cervus elaphus) population showing
signs of inbreeding depression. European Journal
of Wildlife Management, 53, 61-67.
9. Senn, H.V. & Pemberton, J.M. (2009) Variable
extent of hybridization between invasive sika
(Cervus nippon) and native red deer (Cervus elaphus)
in a small geographical area. Molecular Ecology,
18, 862-876.
Some of the ancient red deer
bone and antler fragments
from which DNA was
extracted
