Signatures of Demography and Recombination at Coding Genes in Naturally-Distributed Populations of Arabidopsis Lyrata Subsp. Petraea

Demography impacts the observed standing level of genetic diversity present in populations. Distinguishing the relative impacts of demography from selection requires a baseline of expressed gene variation in naturally occurring populations. Six nuclear genes were sequenced to estimate the patterns and levels of genetic diversity in natural Arabidopsis lyrata subsp. petraea populations that differ in demographic histories since the Pleistocene. As expected, northern European populations have genetic signatures of a strong population bottleneck likely due to glaciation during the Pleistocene. Levels of diversity in the northern populations are about half of that in central European populations. Bayesian estimates of historical population size changes indicate that central European populations also have signatures of population size change since the last glacial maxima, suggesting that these populations are not as stable as previously thought. Time since divergence amongst northern European populations is higher than amongst central European populations, suggesting that the northern European populations were established before the Pleistocene and survived glaciation in small separated refugia. Estimates of demography based on expressed genes are complementary to estimates based on microsatellites and transposable elements, elucidating temporal shifts in population dynamics and confirming the importance of marker selection for tests of demography.     

Back to the brink: Phylogeography and demographic history of the endangered Torreya jackii

Both paleoclimatic change and anthropogenic habitat destruction can have adverse effects on species demography and, in turn, could lead a species towards being endangered and rare. Understanding the relative importance of these natural and anthropogenic factors driving species endangerment and rarity is thus crucial for effective conservation planning but remains elusive. Here, we examine the phylogeography and demographic history of an endangered conifer species in China, Torreya jackii Chun, and assess the relative importance of natural and anthropogenic factors that might have put the species in its endangered state. We collected tissue samples from all the 13 extant wild populations, and analyzed the genetic variation using eight nuclear microsatellites and four chloroplast and one mitochondrial DNA fragments. We found low genetic and nucleotide diversities, which could explain the absence of spatial and phylogeographic structure. Using a hierarchical approximate Bayesian computation technique, we identified the demographic scenario that best fits the genetic data and found that effective population size was low at least 200 000 years ago but expanded after the last glacial maximum (LGM). The paleoclimatic niche model revealed a profound effect of precipitation on the distribution of T. jackii and predicted that the current distribution areas were suitable during the LGM. Despite the post-LGM expansion, the best-supported scenario showed a dramatic population collapse during the past 300 years, when anthropogenic disturbances also increased dramatically. Overall, our study sheds light on how historical factors and human impacts jointly threaten the persistence of a species, and these aspects should be duly considered in species conservation planning.     

Revisiting the phylogeography and demography of European badgers (Meles meles) based on broad sampling,multiple markers and simulations

Although the phylogeography of European mammals has been extensively investigated since the 1990s, many studies were limited in terms of sampling distribution, the number of molecular markers used and the analytical techniques employed, frequently leading to incomplete postglacial recolonisation scenarios. The broad-scale genetic structure of the European badger (Meles meles) is of interest as it may result from historic restriction to glacial refugia and/or recent anthropogenic impact. However, previous studies were based mostly on samples from western Europe, making it difficult to draw robust conclusions about the location of refugia, patterns of postglacial expansion and recent demography. In the present study, continent-wide sampling and analyses with multiple markers provided evidence for two glacial refugia (Iberia and southeast Europe) that contributed to the genetic variation observed in badgers in Europe today. Approximate Bayesian computation provided support for a colonisation of Scandinavia from both Iberian and southeastern refugia. In the whole of Europe, we observed a decline in genetic diversity with increasing latitude, suggesting that the reduced diversity in the peripheral populations resulted from a postglacial expansion processes. Although MSVAR v.1.3 also provided evidence for recent genetic bottlenecks in some of these peripheral populations, the simulations performed to estimate the method''s power to correctly infer the past demography of our empirical populations suggested that the timing and severity of bottlenecks could not be established with certainty. We urge caution against trying to relate demographic declines inferred using MSVAR with particular historic or climatological events.     

Effects of species biology on the historical demography of sharks and their implications for likely consequences of contemporary climate change

Climate variation is an important factor shaping the demographic histories of many marine species, though impacts likely differ depending on species life history, habitat preferences and ecology. Investigating how species responded to historic climate fluctuations may provide critical insights into a species’ response to current climate change. Despite their ecological diversity, shark species share many similar life history characteristics and may be especially vulnerable to anthropogenic and climate impacts. We compared patterns of genetic variability, mismatch distributions and demographic reconstructions from coalescence approaches among temperate and tropical shark species with differing ecological characteristics, to investigate the effect of the past glaciation cycles on population abundance. Genetic diversity at two mitochondrial DNA regions (ND2 and control region) was assayed in four North Pacific species, Pacific spiny dogfish, Pacific sleeper sharks, salmon shark, and bluntnose sixgill shark. In addition, control region sequences acquired from GenBank for five shark species [tope shark (California/Australia), white shark (California), blacktip shark (eastern and western Gulf of Mexico), lemon shark (Bahamas), and whale shark] were analyzed. General patterns in genetic diversity, mismatch analyses and Bayesian skyline plots supported our hypothesis that species biology affected the impact of climate variation on demographic history. Consequently, our results suggest that effects of contemporary climate change on sharks may be to some degree predictable from species biology, distribution, habitat and the impact of past climate events.     

Holarctic genetic structure and range dynamics in the woolly mammoth

Ancient DNA analyses have provided enhanced resolution of population histories in many Pleistocene taxa. However, most studies are spatially restricted, making inference of species-level biogeographic histories difficult. Here, we analyse mitochondrial DNA (mtDNA) variation in the woolly mammoth from across its Holarctic range to reconstruct its history over the last 200 thousand years (kyr). We identify a previously undocumented major mtDNA lineage in Europe, which was replaced by another major mtDNA lineage 32–34 kyr before present (BP). Coalescent simulations provide support for demographic expansions at approximately 121 kyr BP, suggesting that the previous interglacial was an important driver for demography and intraspecific genetic divergence. Furthermore, our results suggest an expansion into Eurasia from America around 66 kyr BP, coinciding with the first exposure of the Bering Land Bridge during the Late Pleistocene. Bayesian inference indicates Late Pleistocene demographic stability until 20–15 kyr BP, when a severe population size decline occurred.     

A range-wide genetic bottleneck overwhelms contemporary landscape factors and local abundance in shaping genetic patterns of an alpine butterfly (Lepidoptera: Pieridae: Colias behrii)

Spatial and environmental heterogeneity are major factors in structuring species distributions in alpine landscapes. These landscapes have also been affected by glacial advances and retreats, causing alpine taxa to undergo range shifts and demographic changes. These nonequilibrium population dynamics have the potential to obscure the effects of environmental factors on the distribution of genetic variation. Here, we investigate how demographic change and environmental factors influence genetic variation in the alpine butterfly Colias behrii. Data from 14 microsatellite loci provide evidence of bottlenecks in all population samples. We test several alternative models of demography using approximate Bayesian computation (ABC), with the results favouring a model in which a recent bottleneck precedes rapid population growth. Applying independent calibrations to microsatellite loci and a nuclear gene, we estimate that this bottleneck affected both northern and southern populations 531–281 years ago, coinciding with a period of global cooling. Using regression approaches, we attempt to separate the effects of population structure, geographical distance and landscape on patterns of population genetic differentiation. Only 40% of the variation in F_ST is explained by these models, with geographical distance and least‐cost distance among meadow patches selected as the best predictors. Various measures of genetic diversity within populations are also decoupled from estimates of local abundance and habitat patch characteristics. Our results demonstrate that demographic change can have a disproportionate influence on genetic diversity in alpine species, contrasting with other studies that suggest landscape features control contemporary demographic processes in high‐elevation environments.     

Impacts of the Toba eruption and montane forest expansion on diversification in Sumatran parachuting frogs (Rhacophorus)

Catastrophic events, such as volcanic eruptions, can have profound impacts on the demographic histories of resident taxa. Due to its presumed effect on biodiversity, the Pleistocene eruption of super‐volcano Toba has received abundant attention. We test the effects of the Toba eruption on the diversification, genetic diversity, and demography of three co‐distributed species of parachuting frogs (Genus Rhacophorus) on Sumatra. We generate target‐capture data (~950 loci and ~440,000 bp) for three species of parachuting frogs and use these data paired with previously generated double digest restriction‐site associated DNA (ddRADseq) data to estimate population structure and genetic diversity, to test for population size changes using demographic modelling, and to estimate the temporal clustering of size change events using a full‐likelihood Bayesian method. We find that populations around Toba exhibit reduced genetic diversity compared with southern populations, and that northern populations exhibit a shift in effective population size around the time of the eruption (~80 kya). However, we infer a stronger signal of expansion in southern populations around ~400 kya, and at least two of the northern populations may have also expanded at this time. Taken together, these findings suggest that the Toba eruption precipitated population declines in northern populations, but that the demographic history of these three species was also strongly impacted by mid‐Pleistocene forest expansion during glacial periods. We propose local rather than regional effects of the Toba eruption, and emphasize the dynamic nature of diversification on the Sunda Shelf.     

A Swedish subfossil find of a bowhead whale from the late Pleistocene: shore displacement,paleoecology in south-west Sweden and the identity of the Swedenborg whale (Balaena swedenborgii Liljeborg, 1867)

The Swedenborg whale Balaena swedenborgii Liljeborg, 1867, is a baleen whale species believed to have existed in the North Sea from the period when the inland ice melted around 13,000 before present (BP) until about 8000 years ago. The first bones attributed to this species were found in Sweden in 1705. When whale remains were discovered on the Swedish west coast during the extension work of a motorway extension, it was speculated that this could be a specimen of the extinct Swedenborg whale. The bones were found 72 m above the present-day sea level embedded in glacial mud. Shelly remains of marine organisms were present in the deposit surrounding the whale-fall, and sediments with the associated specimens were therefore collected for further analyses. We applied radiocarbon dating, thin sectioning, morphological analyses, ancient DNA typing and analyses of the associated shelly assemblage in an interdisciplinary effort to understand the circumstances of this fossil whale-fall. Our results show that the whale is not the putative species B. swedenborgii, but a bowhead whale Balaena mysticetus. The results also indicate that the whale must have been rapidly covered by glacial sediments, highlighting the speed of the deglacial process in the area.     

Genetics at the verge of extinction: insights from the Iberian lynx

Population viability might become compromised by the loss of genetic diversity and the accumulation of inbreeding resulting from population decline and fragmentation. The Iberian lynx (Lynx pardinus) provides a paradigmatic example of a species at the verge of extinction, and because of the well‐documented and different demographic histories of the two remaining populations (Doñana and Andújar), it provides the opportunity to evaluate the performance of analytical methods commonly applied to recently declined populations. We used mitochondrial sequences and 36 microsatellite markers to evaluate the current genetic status of the species and to assess the genetic signatures of its past history. Mitochondrial diversity was extremely low with only two haplotypes, alternatively fixed in each population. Both remnant populations have low levels of genetic diversity at microsatellite markers, particularly the population from Doñana, and genetic differentiation between the two populations is high. Bayesian coalescent‐based methods suggest an earlier decline starting hundreds of years ago, while heterozygosity excess and M‐ratio tests did not provide conclusive and consistent evidence for recent bottlenecks. Also, a model of gene flow received overwhelming support over a model of pure drift. Results that are in conflict with the known recent demography of the species call for caution in the use of these methods, especially when no information on previous demographic history is available. Overall, our results suggest that current genetic patterns in the Iberian lynx are mainly the result of its recent decline and fragmentation and alerts on possible genetic risks for its persistence. Conservation strategies should explicitly consider this threat and incorporate an integrated genetic management of wild, captive and re‐introduced populations, including genetic restoration through translocations.     

Phylogeography and genetic structure of the orchid Himantoglossum hircinum (L.) Spreng. across its European central–marginal gradient

Aim This study aims to link demographic traits and post‐glacial recolonization processes with genetic traits in Himantoglossum hircinum (L.) Spreng (Orchidaceae), and to test the implications of the central–marginal concept (CMC) in Europe. Location Twenty sites covering the entire European distribution range of this species. Methods We employed amplified fragment length polymorphism (AFLP) markers and performed a plastid microsatellite survey to assess genetic variation in 20 populations of H. hircinum located along central–marginal gradients. We measured demographic traits to assess population fitness along geographical gradients and to test for correlations between demographic traits and genetic diversity. We used genetic diversity indices and analyses of molecular variance (AMOVA) to test hypotheses of reduced genetic diversity and increased genetic differentiation and isolation from central to peripheral sites. We used Bayesian simulations to analyse genetic relationships among populations. Results Genetic diversity decreased significantly with increasing latitudinal and longitudinal distance from the distribution centre when excluding outlying populations. The AMOVA revealed significant genetic differentiation among populations (F_ST = 0.146) and an increase in genetic differentiation from the centre of the geographical range to the margins (except for the Atlantic group). Population fitness, expressed as the ratio N_R/N, decreased significantly with increasing latitudinal distance from the distribution centre. Flower production was lower in most eastern peripheral sites. The geographical distribution of microsatellite haplotypes suggests post‐glacial range expansion along three major migratory pathways, as also supported by individual membership fractions in six ancestral genetic clusters (C1–C6). No correlations between genetic diversity (e.g. diversity indices, haplotype frequency) and population demographic traits were detected. Main conclusions Reduced genetic diversity and haplotype frequency in H. hircinum at marginal sites reflect historical range expansions. Spatial variation in demographic traits could not explain genetic diversity patterns. For those sites that did not fit into the CMC, the genetic pattern is probably masked by other factors directly affecting either demography or population genetic structure. These include post‐glacial recolonization patterns and changes in habitat suitability due to climate change at the northern periphery. Our findings emphasize the importance of distinguishing historical effects from those caused by geographical variation in population demography of species when studying evolutionary and ecological processes at the range margins under global change.     

Mixed Fortunes: Ancient Expansion and Recent Decline in Population Size of a Subtropical Montane Primate,the Arunachal Macaque Macaca munzala

Quaternary glacial oscillations are known to have caused population size fluctuations in many temperate species. Species from subtropical and tropical regions are, however, considerably less studied, despite representing most of the biodiversity hotspots in the world including many highly threatened by anthropogenic activities such as hunting. These regions, consequently, pose a significant knowledge gap in terms of how their fauna have typically responded to past climatic changes. We studied an endangered primate, the Arunachal macaque Macaca munzala, from the subtropical southern edge of the Tibetan plateau, a part of the Eastern Himalaya biodiversity hotspot, also known to be highly threatened due to rampant hunting. We employed a 534 bp-long mitochondrial DNA sequence and 22 autosomal microsatellite loci to investigate the factors that have potentially shaped the demographic history of the species. Analysing the genetic data with traditional statistical methods and advance Bayesian inferential approaches, we demonstrate a limited effect of past glacial fluctuations on the demographic history of the species before the last glacial maximum, approximately 20,000 years ago. This was, however, immediately followed by a significant population expansion possibly due to warmer climatic conditions, approximately 15,000 years ago. These changes may thus represent an apparent balance between that displayed by the relatively climatically stable tropics and those of the more severe, temperate environments of the past. This study also draws attention to the possibility that a cold-tolerant species like the Arunachal macaque, which could withstand historical climate fluctuations and grow once the climate became conducive, may actually be extremely vulnerable to anthropogenic exploitation, as is perhaps indicated by its Holocene ca. 30-fold population decline, approximately 3,500 years ago. Our study thus provides a quantitative appraisal of these demographically important events, emphasising the ability to potentially infer the occurrence of two separate historical events from contemporary genetic data.     

Examination of ten thousand years of mitochondrial DNA diversity and population demographics in bowhead whales (Balaena mysticetus) of the Central Canadian Arctic

Mitochondrial DNA (mtDNA) sequences were analyzed from 106 bowhead whale (Balaena mysticetus) specimens dating 471 ± 44 ¹⁴C b.p. –10,290 ± 150 ¹⁴C b.p. to evaluate whether historical changes in distribution and connectivity were detectable in levels of diversity and population structuring in the Central Canadian Arctic. The species has maintained levels of mtDNA diversity over 10,000 yr comparable to other nonbottlenecked large whale species. When compared to data from the Holocene East Greenland/Spitsbergen and contemporary Bering‐Chuckchi‐Beaufort populations, differentiation was low (F_ST≤ 0.005, Φ_ST≤ 0.003) and no temporal or geographical genetic structuring was evident. A combination of analyses suggests that the population has expanded over the past 30,000 ¹⁴C yr. This genetic signature of expansion could result from population growth, admixture of multiple gene pools, or a combination of both scenarios. Despite known climatic change that altered bowhead distribution and led to isolation of populations, there is no detectable population structuring or change in genetic diversity during the Holocene. This may be due to long generation time, occasional population connectivity and a historically large global population. These characteristics warrant caution when interpreting contemporary bowhead whale DNA data, as it is unlikely that any population will be in mutation‐drift equilibrium.     

Postglacial range shift and demographic expansion of the marine intertidal snail Batillaria attramentaria

To address the impacts of past climate changes, particularly since the last glacial period, on the history of the distribution and demography of marine species, we investigated the evolutionary and demographic responses of the intertidal batillariid gastropod, Batillaria attramentaria, to these changes, using the snail as a model species in the northwest Pacific. We applied phylogeographic and divergence population genetic approaches to mitochondrial COI sequences from B. attramentaria. To cover much of its distributional range, 197 individuals collected throughout Korea and 507 publically available sequences (mostly from Japan) were used. Finally, a Bayesian skyline plot (BSP) method was applied to reconstruct the demographic history of this species. We found four differentiated geographic groups around Korea, confirming the presence of two distinct, geographically subdivided haplogroups on the Japanese coastlines along the bifurcated routes of the warm Tsushima and Kuroshio Currents. These two haplogroups were estimated to have begun to split approximately 400,000 years ago. Population divergence analysis supported the hypothesis that the Yellow Sea was populated by a northward range expansion of a small fraction of founders that split from a southern ancestral population since the last glacial maximum (LGM: 26,000–19,000 years ago), when the southern area became re‐submerged. BSP analyses on six geographically and genetically defined groups in Korea and Japan consistently demonstrated that each group has exponentially increased approximately since the LGM. This study resolved the phylogeography of B. attramentaria as a series of events connected over space and time; while paleoceanographic conditions determining the connectivity of neighboring seas in East Asia are responsible for the vicariance of this species, the postglacial sea‐level rise and warming temperatures have played a crucial role in rapid range shifts and broad demographic expansions of its populations.     

Phylogeography and historical demography of the anadromous fish Leucopsarion petersii in relation to geological history and oceanography around the Japanese Archipelago

Phylogeographical patterns of marine and diadromous organisms are often influenced by dynamic ocean histories. For example, the marine realm around the Japanese Archipelago is an interesting area for phylogeographical research because of the wide variation in the environments driven by repeated shifts in sea level in the Quaternary. We analysed mitochondrial cyt b gene and nuclear myh6 gene sequences for individuals collected from throughout the range of the anadromous fish Leucopsarion petersii to assess the lineage divergence, phylogeographical pattern and historical demography in relation to geological history and oceanographic features around the archipelago. Leucopsarion petersii has two major lineages (the Japan Sea and Pacific Ocean lineages), which diverged during the late-early to middle Pleistocene. Geographical distributions of the two lineages were closely related to the pathways of the two warm currents, the Tsushima Current and the Kuroshio Current, that flow past the archipelago. Evidence of introgressive hybridization between these lineages was found at two secondary contact zones. Demographic tests suggested that the Japan Sea and Pacific Ocean lineages carried the genetic signal of different historical demographic processes, and these signals are probably associated with differences in habitat stability during recent glacial periods. The Japan Sea lineage has a larger body-size and more vertebrae, probably in relation to severe habitat conditions through Pleistocene climatic oscillations. Thus, the two lineages have long independent evolutionary histories, and the phylogeographical structure and demography of this species have been influenced both by historical events and the present-day oceanography around the Japanese Archipelago.     

Molecular genetic analysis of the Shantar summer group of bowhead whales (Balaena mysticetus L.) in the Okhotsk Sea

The results of molecular genetic analysis (full-length sequences of the mtDNA cytochrome b gene and control region and the allelic composition of 14 microsatellite loci) of 65 tissue samples from the endangered bowhead whale (Balaena mysticetus) population of the Sea of Okhotsk are presented. The data obtained enable the suggestion that at present, the state of the Sea of Okhotsk bowhead whale population is relatively stable.     

Genetic diversity and differentiation in a wide ranging anadromous fish,American shad (Alosa sapidissima), is correlated with latitude

Studies that span entire species ranges can provide insight into the relative roles of historical contingency and contemporary factors that influence population structure and can reveal patterns of genetic variation that might otherwise go undetected. American shad is a wide ranging anadromous clupeid fish that exhibits variation in demographic histories and reproductive strategies (both semelparity and iteroparity) and provides a unique perspective on the evolutionary processes that govern the genetic architecture of anadromous fishes. Using 13 microsatellite loci, we examined the magnitude and spatial distribution of genetic variation among 33 populations across the species' range to (i) determine whether signals of historical demography persist among contemporary populations and (ii) assess the effect of different reproductive strategies on population structure. Patterns of genetic diversity and differentiation among populations varied widely and reflect the differential influences of historical demography, microevolutionary processes and anthropogenic factors across the species' range. Sequential reductions of diversity with latitude among formerly glaciated rivers are consistent with stepwise postglacial colonization and successive population founder events. Weak differentiation among U.S. iteroparous populations may be a consequence of human‐mediated gene flow, while weak differentiation among semelparous populations probably reflects natural gene flow. Evidence for an effect of reproductive strategy on population structure suggests an important role for environmental variation and suggests that the factors that are responsible for shaping American shad life history patterns may also influence population genetic structure.     

Phylogeography of a habitat specialist with high dispersal capability: the Savi's Warbler Locustella luscinioides

In order to describe the influence of Pleistocene glaciations on the genetic structure and demography of a highly mobile, but specialized, passerine, the Savi's Warbler (Locustella luscinioides), mitochondrial DNA sequences (ND2) and microsatellites were analysed in c.330 individuals of 17 breeding and two wintering populations. Phylogenetic, population genetics and coalescent methods were used to describe the genetic structure, determine the timing of the major splits and model the demography of populations. Savi's Warblers split from its sister species c.8 million years ago and have two major haplotype groups that diverged in the early/middle Pleistocene. One of these clades originated in the Balkans and is currently widespread, showing strong evidence for population expansion; whereas the other is restricted to Iberia and remained stable. Microsatellites agreed with a genetic break around the Pyrenees, but showed considerable introgression and a weaker genetic structure. Both genetic markers showed an isolation-by-distance pattern associated with the population expansion of the eastern clade. Breeding populations seem to be segregated at the wintering sites, but results on migratory connectivity are preliminary. Savi's Warbler is the only known migratory bird species in which Iberian birds did not expand beyond the Pyrenees after the last glaciation. Despite the long period of independent evolution of western and eastern populations, complete introgression occurred when these groups met in Iberia. Mitochondrial sequences indicated the existence of refugia-within-refugia in the Iberian Peninsula during the last glacial period, which is surprising given the high dispersal capacity of this species. Plumage differences of eastern subspecies seemed to have evolved recently through natural selection, in agreement with the glacial expansion hypothesis. This study supports the great importance of the Iberian Peninsula and its role for the conservation of genetic variation.     

The influence of historical landscape change on genetic variation and population structure of a terrestrial salamander (Plethodon cinereus)

Forest loss and fragmentation is expected to shape the genetic structure of amphibian populations and reduce genetic variation. Another factor widely understood to have impacted these same parameters in North America is the range expansion that occurred following glacial retreat at the end of the Pleistocene. The Eastern Red-Backed Salamander (Plethodon cinereus) has been subjected to both processes. In this context, we investigated the historical events that are likely to have shaped genetic variation in this species using a panel of six microsatellite markers screened on individuals sampled across ten localities in northeastern Indiana, USA. We found low genetic diversity across forest patches and minimal differentiation. We expected population structure associated with forest fragmentation to result from genetic drift in isolation but instead found that a balance between gene flow and drift was ~50 times more likely. Ratios of allele number and range (M), and coalescent modeling of population demography suggested the occurrence of marked historic decline in effective population size across the region. Taken together, the data point to a loss of genetic variation which preceded deforestation over the past 200 years. This result indicates an important role for ancient demographic processes in shaping current genetic variation that may make it difficult to detect the effect of recent habitat fragmentation.     

Population dynamics of American horseshoe crabs—historic climatic events and recent anthropogenic pressures

Populations of the American horseshoe crab, Limulus polyphemus, have declined, but neither the causes nor the magnitude are fully understood. In order to evaluate historic demography, variation at 12 microsatellite DNA loci surveyed in 1218 L. polyphemus sampled from 28 localities was analysed with Bayesian coalescent‐based methods. The analysis showed strong declines in population sizes throughout the species’ distribution except in the geographically isolated southern‐most population in Mexico, where a strong increase in population size was inferred. Analyses suggested that demographic changes in the core of the distribution occurred in association with the recolonization after the Ice Age and also by anthropogenic effects, such as the past overharvest of the species for fertilizer or the current use of the animals as bait for American eel (Anguilla rostrata) and whelk (Busycon spp.) fisheries. This study highlights the importance of considering both climatic changes and anthropogenic effects in efforts to understand population dynamics—a topic which is highly relevant in the ongoing assessments of the effects of climate change and overharvest.     

Characterization of 25 microsatellite loci in bowhead whales (Balaena mysticetus)

Bowhead whales (Balaena mysticetus) experienced a severe demographic population bottleneck caused by commercial whaling that ceased in 1914. Aboriginal subsistence whale harvests have continued and are managed by the International Whaling Commission. In an effort to provide management advice for bowhead whales, 25 microsatellite loci were isolated from genomic DNA libraries. This panel of markers will be utilized to analyse stock structure hypotheses of current bowhead whale populations.