Going Coastal: Shared Evolutionary History between Coastal British Columbia and Southeast Alaska Wolves (Canis lupus)
Cook JA (2011) Going Coastal: Shared Evolutionary History between Coastal British Columbia and
Southeast Alaska Wolves (Canis lupus). PLoS ONE 6(5): e19582. doi:10.1371/journal.pone.0019582
Going Coastal: Shared Evolutionary History between Coastal British Columbia and Southeast Alaska Wolves (Canis lupus )
Byron V. Weckworth 0
Natalie G. Dawson 0
Sandra L. Talbot 0
Melanie J. Flamme 0
Joseph A. Cook 0
Robert C. Fleischer, Smithsonian Institution National Zoological Park, United States of America
0 1 Faculty of Environmental Design, University of Calgary , Calgary, Alberta , Canada , 2 Department of Biology and Museum of Southwestern Biology, University of New Mexico , Albuquerque , New Mexico, United States of America, 3 U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, United States of America, 4 National Park Service, Yukon-Charley Rivers National Preserve , Fairbanks, Alaska , United States of America
Background: Many coastal species occupying the temperate rainforests of the Pacific Northwest in North America comprise endemic populations genetically and ecologically distinct from interior continental conspecifics. Morphological variation previously identified among wolf populations resulted in recognition of multiple subspecies of wolves in the Pacific Northwest. Recently, separate genetic studies have identified diverged populations of wolves in coastal British Columbia and coastal Southeast Alaska, providing support for hypotheses of distinct coastal subspecies. These two regions are geographically and ecologically contiguous, however, there is no comprehensive analysis across all wolf populations in this coastal rainforest. Methodology/Principal Findings: By combining mitochondrial DNA datasets from throughout the Pacific Northwest, we examined the genetic relationship between coastal British Columbia and Southeast Alaska wolf populations and compared them with adjacent continental populations. Phylogenetic analysis indicates complete overlap in the genetic diversity of coastal British Columbia and Southeast Alaska wolves, but these populations are distinct from interior continental wolves. Analyses of molecular variation support the separation of all coastal wolves in a group divergent from continental populations, as predicted based on hypothesized subspecies designations. Two novel haplotypes also were uncovered in a newly assayed continental population of interior Alaska wolves. Conclusions/Significance: We found evidence that coastal wolves endemic to these temperate rainforests are diverged from neighbouring, interior continental wolves; a finding that necessitates new international strategies associated with the management of this species.
Funding: Funding was provided by the U.S. Geological Survey Alaska Science Center, Yukon-Charley Rivers National Reserve, U.S. Fish & Wildlife Service, United
States Department of Agriculture Forest Service Alaska Region and Forest Sciences Laboratory, and National Science Foundation (NSF DEB 0196095 and 0415668).
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
Evaluating phylogeographic patterns across multiple species can
aid in deciphering the historical processes that drive community
assemblage and species diversification throughout regions of interest
. For example, geographic isolation due to glacial vicariance can
fragment species into genetically disjunct populations. Over time,
these populations may diverge into distinct evolutionary lineages. In
North America, the regional fauna along the North Pacific Coast
exhibit phylogeographic patterns consistent with long-term isolation
due to large scale historical climatic events , with a growing
number of distinctive and often endemic coastal lineages identified
across an array of organisms . A clear view of the biogeographic
history and spatial distributions of these lineages is important for
assessing and maintaining genetic diversity in this distinctive biome;
however, most species remain poorly documented, precluding the
rigorous application of scientific knowledge to objective management.
Recent molecular studies of wolves supported both
phylogeographic and ecological mechanisms for diversification of wolves
(Canis lupus) in western North America . In particular, wolf
populations along the North Pacific Coast have previously been
identified as morphologically [17,18] and genetically distinct
[10,11], suggesting independent phylogeographic histories of
coastal and continental lineages. Weckworth et al. [10,11]
demonstrated the distinctiveness of Alexander Archipelago and
adjoining coastal (Alaska) wolves from adjacent continental
populations and attributed diversification to barriers to gene flow
through the coastal mountains. To the south of these Alaska
populations, Mu noz-Fuentes et al.  attribute the genetic
distinctiveness of coastal and island wolves from inland British
Columbia (BC) wolves to the unique ecological and environmental
characteristics of the region. To date, no genetic analysis has
included both coastal Southeast Alaska and coastal BC wolves to
assess their similarity. Nevertheless, both coastal BC and coastal
Southeast Alaska wolves demonstrate life history characteristics
distinct from inland continental populations .
Phylogeographic studies of multiple carnivore species found along
the North Pacific Coast of North America reveal shared histories
between Southeast Alaska and coastal British Columbia [5,23,24].
Given the new investigations that independently describe unique
coastal wolves in either British Columbia or Southeast Alaska, a
comprehensive analysis of the phylogeographic and population
dynamics of both groups of coastal wolves is needed. Using mtDNA
data, we augment previous analyses with a combined dataset of coastal
BC and Southeast Alaskan specimens and include an expanded series
of continental populations from interior Alaska, British Columbia and
Yukon Territory to examine phylogenetic relationships,
phylogeographic history, and the population dynamics of coastal wolves across
their entire Northwest North American distribution.
This research was undertaken with approval from the National
Park Services Institutional Animal Care and Use Committee
(protocol approval number NPS IACUC 2010-1).
The sampling regime emphasized localities within continental
and coastal Southeast Alaska and British Columbia (Figure 1), as
described in Weckworth et al. [10,11], including individual islands
(REV) or island groups (KMW, POW) in the Alexander
Archipelago; coastline of Southeast Alaska (MCN, MCS); interior
Alaska (FAI); interior British Columbia (IBC); Yukon Territory
(YUK). Eight populations, representing 193 individuals from
Weckworth et al. (; Text S1) were used in this study. We added
30 individuals from Yukon-Charley Rivers National Preserve
(YC; Text S1), extending the previous continental sampling to
the north. Additionally, we incorporated sequence data of 75
individuals from coastal British Columbia populations first
presented in Mu noz-Fuentes et al. ; Vancouver Island (VI),
three coastal populations in central BC (C1, C2, and C3), and one
population in southern, coastal BC (CS) (Text S1). These
sequences, along with sequences from pre-extirpated populations in
the conterminous United States (; Text S1) were obtained
from GenBank. In total, the combined datasets yielded a sum of
310 individuals (including 30 previously unpublished samples from
YC) representing 14 contemporary populations and 7 haplotypes
from extirpated populations in the conterminous U.S. . To
accommodate differences in sequence length among these
datasets, we reduced our original 613 bp segment of the mtDNA
 to the overlapping 426 bp to match the coastal BC haplotypes
from Mu noz-Fuentes et al. . This subset of sequence includes
the mtDNA tRNAs (91 bp) and portion of the control region
(335 bp). Extraction and amplification protocols for the 30 novel
individuals followed Weckworth et al. .
Phylogenetic relationships among haplotypes were examined by
constructing a network using the median-joining method available
in Network v.4.6 . Arlequin v3.01  was used to
calculate haplotype and nucleotide diversity for each population. We
generated pairwise WST statistics  in Arlequin to assess
population differentiation. PASW Statistics 18.0 (SPSS Inc.,
Chicago, USA) was used to visualize the genetic relationships
among populations with multidimensional scaling using pairwise
To test significant geographic divisions of hypothesized a priori
subspecies groups, we used analyses of molecular variance
(AMOVA ,) in Arlequin . This hierarchical analysis of
variance partitions the total variance into covariance
components due to differences among groups, among populations
within groups and within populations. These calculations were
performed using pairwise distances. In addition to the a priori
Pacific Northwest and Alaskan subspecies hypotheses (i.e.
[11,31,32]) and the broad-scale divisions suggested by the
analysis of microsatellite loci (i.e., continental-coastal
designations ;), we also experimented with various a posteriori groups
in AMOVA analyses. The a posteriori groups were suggested by
the ambiguous placement of samples from British Columbia,
analyses of nuclear DNA population trees, and Bayesian
analyses of population structuring, as well as those suggested by
geographical isolation (see below and ). We assumed that the
best geographic subdivisions were significantly different from
random distributions and had maximum among group
variance (WCT values). Thus, if there is concordance between the
distribution of genetic subdivisions, and presumed subspecies
delineations, values of WCT should be significant, and larger than
To investigate the distribution of genetic diversity over the
contemporary samples, an F-statistics based spatial analysis of
molecular variance (SAMOVA) was performed using SAMOVA
1.0 . This method defines groups of populations that are
geographically homogenous and maximally differentiated. The
groupings that maximized FCT while minimizing FSC were
assumed to be the most probable geographical subdivisions.
The genetic diversity described here is similar to the results of
previously published studies (e.g. [11,15]). Based on the shorter
sequence length, we recorded 20 haplotypes across all individuals
in the study (Figure 1) including haplotypes from extirpated
regions (Not shown in Figure 1). There was one indel present,
which was treated as a distinct character. The reduced sequence
segment did not include a site that differentiated between two pairs
of haplotypes (A and M, and C and L) from Weckworth et al. ;
haplotype designations of A and C were included in this
manuscript. Two previously undocumented haplotypes, S and U,
were discovered in the Yukon-Charley population. This
population also shares additional haplotypes with interior Alaska wolf
populations (represented in this study by Fairbanks (FAI) area
samples). Three haplotypes (G, H, I) are restricted to coastal British
Columbia and Southeast Alaska. Haplotypes G and H are shared
between coastal wolves in Southeast Alaska and coastal British
Columbia. Haplotype I, however, is found only in Southeast
Alaska wolves. The most common haplotype (F) found in the
coastal region is also shared with wolves in interior British
The haplotype network (Figure 2) includes 4 phylogroups in
North America that are similar to those described in Weckworth
et al. . Phylogroup 1 includes the widespread continental
haplotype (A) that was ubiquitous across northern Alaska and
western Canada populations. Contemporary haplotypes in
Phylogroup 1 (haplotypes A and S) have a distribution corresponding
to C. l. occidentalis. However, the addition of the lu52 haplotype
from a historical specimen collected in Oklahoma  represents
C. l. nubilus, and is not consistent with Nowaks  proposed
Coastal populations were predominately found in Phylogroup 2,
which included haplotype F, present in 184 individuals from
Southeast Alaska, and coastal and interior BC. This phylogroup
also included haplotype H which is restricted to coastal BC and the
southern mainland coastal area in Southeast Alaska. Haplotype G
is shared between the North Pacific Coast and the Yukon,
corroborating the southern refugial origin of some individuals
, or reflecting the lack of sorting of ancestral genetic variation.
With the exception of the YUK individual, and possibly the BC
individuals, samples were within the geographic range of C. l.
nubilus (; samples from BC were collected at or near the
boundary between C. l. nubilus and C. l. occidentalis). The presence
of haplotypes from extirpated southern populations (lu48, lu49,
lu53) in Phylogroup 2 (Figure 2) indicates a wider geographic
distribution of Phylogroup 2 through the conterminous U.S., and
supports the assertion of a southern refugial source for coastal
wolves [10,11]. Due to the loss of informative sites with the
truncation of sequences from 611 to 426 bp, coastal wolves are not
clustered in a single phylogroup (haplotype I is in Phylogroup 3) as
found by Weckworth et al. .
Phylogroup 3 included haplotypes found within interior Alaska
and the Yukon (D, K, and C). However, the displaced haplotype I,
which is only found in one population in Southeast Alaska, is found
within this phylogroup, which would suggest mixed refugial origins of
coastal wolves, or contemporary gene flow between interior and
coastal wolves. Individuals with haplotypes in phylogroup 3 (except
for haplotype I) are within the defined range of C. l. occidentalis.
Phylogroup 4 represents a distinct southern refugial group identified
by Leonard et al.  as well as the endangered Mexican wolves (C. l.
baileyi), and is diverged from other North American wolves (Figure 2).
Population information for the haplotypes from extirpated
populations is not available and consequently these sequences were
not included in AMOVA analyses. When populations were divided
into coastal and continental groups , AMOVA results (Table 1,
Model A) indicate that 50.7% of all genetic variation distinguished
geographic groups (P = 0.002), 34.1% of variation was apportioned
within populations (P,0.0001), and 13.0% was relegated among
populations within groups (P,0.0001). Model A partitions the
populations into two groups that correspond to either the
distribution of C. l. nubilus or C. l. occidentalis , testing the validity
of the two subspecies. Transferring coastal BC populations from the
coastal group into their own distinct group (i.e. consistent with three
subspecies, adding BC coastal as C. l. fuscus) results in a reduction of
WCT, although the value is still significant (Table 1, Model B). Model
Figure 2. Haplotype network. Haplotype network for 20 haplotypes from 426 bp of mtDNA. Each black circle represents a single mutational
change. The white circles indicate haplotypes from extirpated populations in the southern U.S . The coloured circles and haplotype labels are
consistent with Figure 1. The size of each circle is proportional to the observed frequency of a given haplotype. The maximum circle size is for N = 50,
if N.50 the actual frequency is indicated. The black square represents a missing or hypothetical haplotype. Shaded regions define phylogroups 1, 2, 3
and 4 are labeled P1, P2, P3 and P4, respectively.
C incorporates coastal BC populations with interior Alaska and
Canada populations to test whether or not the coastal BC
populations should be included in C. l. occidentalis . Model D is
a general AMOVA test within C. l. occidentalis splitting the
populations into three groups: coastal wolves, interior Alaska wolves,
and interior Canada wolves. This test result was also significant
(Table 1). Finally, Model E tests subspecies designations applied by
Hall and Kelson  to wolves of the North Pacific and Alaska (e.g.,
C. l. ligoni applied to wolves of the Alexander Archipelago and
southeast mainland, C. l. fuscus for coastal BC, C. l. pambasileus applied
to wolves elsewhere in Alaska, and C. l. columbianus describing wolves
of the Yukon and interior BC). Overall, the results of the AMOVA
analysis suggest that C. l. ligoni is genetically distinct from C. l.
occidentalis when coastal British Columbia is included.
Population subdivision based on mtDNA was calculated using
SAMOVA. The results indicated that genetic differentiation
among groups was maximized at six groups (FCT = 67.06) while
differentiation between populations within groups dropped below
zero (FSC = 20.15). All of the continental populations and MCN
were each in a group by themselves. The sixth group was
composed of all the coastal populations (except for MCN).
Population pairwise WST values indicate geographic structuring
across the landscape for many populations. Pairwise estimates of
WST (Table 2) are consistent with FST in microsatellites  and
significantly correlated (Mantel Test, p = 0.0018), with genetic
distances highest between coastal and continental population
comparisons . Coastal BC populations in proximity to each
other (C1, C2, and C3) were not significantly different from each
other (using the 426 bp sequence in this study) and therefore, were
placed together as a single group (CBC) for pairwise WST results
(Table 2). All Southeast Alaska populations other than MCN
(which has a unique haplotype) were not significantly differentiated
from Vancouver Island, and the MCS population (southern
Southeast Alaska) was not significantly differentiated from any of
the coastal BC populations. Other Southeast Alaska island
populations are significantly differentiated from one another as
well as from all coastal British Columbia populations (Table 2).
Multi-dimensional scaling ordinations of the spatial patterns of
genetic variation among the populations (Figure 3) show a distinct
separation of coastal and continental populations, with the
exception of MCN.
Independent studies previously demonstrated that coastal
lineages of wolves in Southeast Alaska and coastal British Columbia
subsequent bottlenecks. Weckworth et al.  analyzed the same
individuals using hypervariable nuclear microsatellites and found
no evidence of recent or historic bottlenecks across any of the
Southeast Alaska populations. However, the methods they used
to detect bottlenecks have decreased statistical power if a severe
bottleneck (e.g. the population was decreased to fewer than 25
effective breeders [Ne]) occurred more than 100 generations (ca.
4Ne) ago .
Two of the four haplotypes identified in the coastal lineage of
wolves (F and G) were found in continental populations. Haplotype
F was found in 87% of all coastal individuals, and was identified
in some continental populations (e.g. interior BC; this study;
haplotype equivalent lu38 in ) suggesting gene flow from
coastal populations into adjacent interior BC populations.
Haplotype G was found in only 6 individuals here, but the
equivalent haplotype has been identified broadly and
predominantly across continental populations (lu32, ) and may indicate
gene flow into coastal populations. Conversely, these patterns may
simply correspond to incomplete lineage sorting since expansion
from refugial populations, or historic gene flow, as assessments of
nuclear microsatellite data indicate little contemporary gene flow
between coastal and continental populations . Further analyses
using microsatellite or other nuclear loci should be extended to
include the entire coastal wolf distribution and adjacent
continental populations and, combined with next generation sequencing,
would further clarify contemporary levels of genetic exchange and
the evolutionary history of these populations.
Analysis of molecular variance for five a posteriori models of groupings according to different subspecies designations previously identified using morphological data.
[KMW, MCN, MCS, POW, REV, VI, CBC, CS] [IBC, YC, FAI, YUK]
[KMW, MCN, MCS, POW, REV] [VI, CBC, CS] [IBC, YC, FAI, YUK]
[KMW, MCN, MCS, POW, REV] [VI, CBC, CS, IBC, YC, FAI, YUK]
[KMW, MCN, MCS, POW, REV, VI, CBC, CS,] [YC, FAI] [IBC, YUK]
[KMW, MCN, MCS, POW, REV] [VI, CBC, CS] [YC, FAI] [IBC, YUK]
[10,11,15] are each distinct from other North American continental
wolves. Our analyses are the first to include specimens from both
coastal Alaska and coastal British Columbia and indicate a close
evolutionary relationship between all coastal wolves relative to
continental wolves. Wolves in western North America mirror a
phylogeographic pattern of distinctive coastal and continental
lineages repeatedly identified in other mammals such as black bears
, marten [24,34,35], flying squirrels [36,37], deer mice  as well
as multiple plant species . Coastal lineages tend to share a
similar phylogeographic history, as reflected in mitochondrial
genomes, which are divergent from nominally conspecific
continental populations. In those cases where independent nuclear
markers have been assessed (e.g. [10,35]), this coastal/continental
divergence has been corroborated.
Although both coastal British Columbia and Southeast Alaska
wolves share similar evolutionary histories, genetic diversity varies
among the regions. Haplotype diversity was similar across the
combined regions, with the exception of a fourth haplotype (I)
that was unique to five individuals from the Juneau region of the
northern mainland coastal area (MCN) of Southeast Alaska.
Populations of island wolves in coastal BC generally possess
multiple haplotypes, whereas most island wolves in Southeast
Alaska were monotypic for the common coastal haplotype (F),
suggesting that either gene flow between mainland coastal and
island wolves is higher in BC than Southeast Alaska, or that
island wolves in Southeast Alaska have been subjected to extreme
genetic drift, perhaps due to small founding populations or
Pairwise population comparisons calculating WST. Bold-italicized numbers indicate significant p-values (a = 0.05). Abbreviations as per text and Figure 1 (CBC = coastal
British Columbia and is the combined data of C1, C2 and C3).
Mu noz-Fuentes et al.  and Weckworth et al.  cite the
distinctive ecological characteristics of the coastal biome of the
North Pacific Coast region and geographic isolation, respectively,
as the major mechanisms for diversification of coastal wolves.
Weckworth et al.  also provide evidence that wolves in
northern latitudes in North America emerged from different refugia.
After colonization, ecology and isolation, as mechanisms of
diversification, are not mutually exclusive. The ecological
argument for parapatric divergence as the contemporary mechanism
for reinforcing the separation of coastal and continental BC
populations  is particularly compelling given the demonstrated
ability of wolves to successfully colonize many different terrestrial
ecosystems. Studies of other taxa in the Pacific Northwest,
particularly Southeast Alaska, have concluded that coastal and
continental lineages evolved in separate refugia during the
Pleistocene (black bears, [4,40]; marten, [5,24]). Unlike wolves,
some of these species are arguably more narrowly restricted to
particular habitats, but, in several cases the continental lineage has
expanded into sympatry with representatives of the coastal lineage
[4,5,24,35]. Intense territoriality of wolves, combined with their
complex social hierarchies, may curtail the establishment of
dispersing continental individuals, and may have consequently
helped to reinforce parapatric divergence between coastal and
continental wolf populations.
The continental populations studied here cover largely intact
habitat across a nearly contiguous range and demonstrate
patterns of genetic diversity that suggest few barriers to gene
flow. In contrast, coastal populations of Southeast Alaska are
distributed across a naturally fragmented region. Anthropogenic
activities such as logging and road building have increased access
and trapping, and the illegal hunting of these populations,
particularly in Southeast Alaska [41,42]. Increased mortality
may result in the continued loss of genetic diversity in these
coastal wolves, or the breakdown of reinforcement mechanisms
that have largely prevented introgression with continental wolves
Weckworth et al.  propose that wolves in Southeast Alaska
originated from a southern refugium, and represent the last
remnants of genetic diversity from extirpated historic populations
of wolves once found in the conterminous United States. Multiple
subspecies of wolves were described for the Pacific Northwest; C. l.
ligoni in Southeast Alaska, C. l. fuscus of coastal BC, Washington
and Oregon (now only extant in coastal BC), and C. l. crassodon on
Vancouver Island [17,18]. Nowaks  revision of subspecific
designations in wolves subsumed these coastal subspecies into a
single widespread subspecies, C. l. nubilus, which extended to wolf
populations across most of the conterminous US and into eastern
Canada. Subsequent molecular perspectives [10,11,15] revealed
distinctive coastal wolves and our analyses support the
distinctiveness of coastal wolves as a single phylogeographic lineage along the
North Pacific Coast that would encompass C. l. ligoni, C. l. fuscus
and C. l. crasodon.
Coastal wolves have been described as distinct Management
Units  in Canada, following Moritz , but currently have
no special management consideration in Southeast Alaska .
Given the imprecision of population estimates for coastal Alaska,
legal and illegal harvest , and the apparent genetic isolation of
coastal wolf populations as a whole  , special caution is
warranted in evaluating the consequences of expected
population declines on wolves in Southeast Alaska, specifically (62
Federal Register 46710). More generally these preliminary
molecular surveys call for a re-evaluation of geographic variation over
the entire range of coastal wolves.
Canis lupus is listed as vulnerable across its global range (North
America, Eurasia, and the Middle East) . The coastal wolves
analyzed here have previously been identified as a subspecies (C. l.
ligoni) restricted to temperate rainforests of coastal Southeast
Alaska and British Columbia. In the U.S., 80% of the terrestrial
biome is managed by the U.S. Forest Service (Tongass National
Forest). These coastal wolves are considered a species  or
subspecies [47,48] of concern in the U.S., and a Management
Indicator Species for the Tongass National Forest . In 1997
the U.S. Fish and Wildlife Service (FWS) was petitioned to list the
coastal wolves of the Alexander Archipelago as a threatened
species under the Endangered Species Act based on wolf viability
in response to timber practices on the Tongass and associated prey
depletion and increased access for wolf trappers and hunters (62
Federal Register 46710). FWS issued a not warranted finding.
Although FWS expected the Alexander Archipelago wolf
populations to decline, the agency did not consider the population to
be in danger of extinction in the foreseeable future because they
expect the population decline to stop at an acceptable level.
Additionally, wolves are known to persist at low numbers in
healthy populations and to be resilient to the activities of man
because of their high reproductive rate and high dispersal
capability (62 Federal Register 46710).
The high dispersal capabilities cited by the FWS presumably
suggest that recruitment of wolves from outside of Southeast
Alaska would mitigate declining populations and loss of genetic
diversity. This study and previous work [10,11,15], consistently
indicate minimal gene flow between coastal and continental
populations. Instead, a more detailed understanding of
recruitment and gene flow between coastal Canadian and coastal
Alaskan populations appears to be essential for effective
transboundary management. However, no international agreements
currently support such analyses. Although wolves can persist
successfully at low population densities, theoretical modeling ,
research on other restricted carnivore populations [51,52] and
empirical data from populations of other island species [53,54]
suggest that prolonged bottlenecking will result in loss of genetic
variation, especially in areas at already low levels of genetic
Previous studies focusing on wolves in the continental United
States found minimal variation among populations (e.g. ). In
high latitude ecosystems, however, it is clear that coastal and
continental wolf populations demonstrate both significant regional
and inter-population differentiation [10,11, this study]. It is
therefore not surprising that mtDNA analyses of a previously
unassayed continental wolf population (Yukon-Charley Rivers
National Preserve) would uncover significant population
differentiation and novel haplotypes. It is possible, and certainly testable,
that these novel haplotypes occur in other unassayed populations,
including those in the adjacent Yukon Territory of Canada.
Habitat of wolves of the Yukon-Charley National Preserve is
protected by the National Park Service, which is explicitly
mandated to assess and maintain variability of wildlife populations
[55,56]. Nevertheless, there are concerns about the long-term
maintenance of genetic variation in this population as the 1520%
mortality due to subsistence, sport hunting and trapping on the
national preserve  is currently being augmented by intensive
predator control efforts intended to reduce wolf predation on
caribou herds by reducing wolf population numbers by 6080%
. Because packs whose territories include Yukon-Charley also
travel outside of the preserve, including into Yukon Territory
[57,59], their social and genetic structure  may be impacted by
management prescriptives fostered by state/provincial and
national management agencies of two countries.
The coastal wolves in Southeast Alaska and coastal British
Columbia represent a distinct portion of the genetic diversity for
all wolves in North America. Moreover, increased sampling across
continental populations will reveal additional variation as
exhibited in Yukon-Charley wolves. Given the intensity of current
efforts to control wolves in many areas, our assessment of
phylogeographic structure across the North Pacific region suggests
that a much more refined understanding of genetic variation is
needed to ensure the persistence of this high profile carnivore
throughout the region.
Wolves are a trans-boundary species and, as demonstrated here,
exhibit metapopulation dynamics that encompass habitats in both
Canada and the US. This necessitates increased international
cooperation for wolf management and conservation. The success
of such geographic integration of management programs has been
demonstrated for other taxonomic groups, particularly migratory
birds . The legal framework for international
collaboration exists in the Framework for Cooperation between the US
Department of the Interior and Environment Canada in the
Protection and Recovery of Wild Species at Risk signed by the
governments of the US and Canada in 1997 , and through the
government-funded North American Commission for
Environmental Cooperation. These agreements recognize wolves as an
international species of conservation concern, but are focused
primarily on the conterminous US where wolf populations were
extirpated by the mid-20th century. The extension of such
international collaborations to include Alaska, British Columbia
and Yukon Territory will encourage recognition of the importance
of wolf populations in regions outside the extirpation zone, and
support the establishment of trans-boundary management plans
that maintain the important ecological and genetic diversity of
these shared northern populations.
Text S1 Sample accession numbers. Description of Canis
lupus GenBank mitochondrial DNA sequences and the location of
original tissue sample if known. Listed by original publication are
populations (abbreviations as given in text), GenBank accession
numbers and when available, in corresponding order, the voucher
number from either University of Alaska Museum of the North
(UAM) or Museum of Southwestern Biology (MSB).
Technological support was provided by the University of Alaska Life
Science Informatics computer cluster (S Houston). Specimens were
provided by the National Park Service, the University of Alaska Museum
of the North and the Museum of Southwestern Biology. Analytical,
laboratory and field assistance were provided by J Burch, J Gust, S
Mariani, T Muhly, D Person and GK Sage. Thanks to S Mariani and S
Farley for providing valuable comments on early drafts of this manuscript.
Conceived and designed the experiments: BVW NGD SLT MJF JAC.
Performed the experiments: BVW NGD SLT MJF. Analyzed the data:
BVW NGD SLT. Contributed reagents/materials/analysis tools: BVW
NGD SLT MJF JAC. Wrote the paper: BVW NGD SLT MJF JAC.
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