Assessing migration patterns of sharp-shinned hawks Accipiter striatus using stable-isotope and band encounter analysis

Intraspecific migration patterns in birds have both spatial and temporal components. Two commonly reported spatial patterns are leap-frog and chain migration. Temporal migration patterns refer to the timing of migration of populations from different breeding latitudes. We investigated the spatial and temporal migration patterns of hatching-year (HY) sharp-shinned hawks Accipiter striatus of interior North America using stable-hydrogen isotope and band encounter analyses. Feather samples were collected from hawks migrating through New Mexico, USA and measured for their stable-hydrogen isotope ratios (δD) to distinguish individuals originating from relatively high and low natal latitudes. We then examined the relationship between feather δD values and passage dates through New Mexico, USA. We also gathered band encounter data from the Bird Banding Lab of the United States Geological Survey to determine the wintering latitudes of HY sharp-shinned hawks relative to their passage date through migration banding sites in interior North America. Combining these data, we found that during fall migration HY sharp-shinned hawks used a chain migration pattern, that is, hawks originating from lower latitudes wintered further south than those from higher latitudes. In addition, birds originating from lower latitudes passed through interior North America earlier than those from higher latitudes. We also found that hawks from higher latitudes were significantly larger than those from lower latitudes, and that females from higher latitudes had significantly higher estimated fat levels than females from lower latitudes.     

Estimation of Species Identification Error: Implications for Raptor Migration Counts and Trend Estimation

Abstract: One of the primary assumptions associated with many wildlife and population trend studies is that target species are correctly identified. This assumption may not always be valid, particularly for species similar in appearance to co-occurring species. We examined size overlap and identification error rates among Cooper's (Accipiter cooperii) and sharp-shinned (A. striatus) hawks specific to a raptor migration count station along the Pacific Coast of North America. Illustrating the difficulty of distinguishing between these 2 species, we found overlap in 7 metrics among species-sex groups and in 2 metrics between species, and a principal components analysis revealed a continuum of discrete clusters for each species-sex combination in morphospace. Among juvenile hawks (n = 940), we found the greatest misidentification rate for male Cooper's hawks (23% of the 156 males were identified as sharp-shinned), lesser error rates for female Cooper's (8%, n = 339) and female sharp-shinned (6%, n = 246), and the lowest misidentification rate for male sharp-shinned hawks (0%, n = 199). We observed a similar pattern of misidentification among adult hawks (n = 48). We attempted to use conditional probabilities (identification rates) from calibration data to calculate the true number of adult and juvenile Cooper's hawks and sharp-shinned hawks. Discrepancies between total number of observed accipiters and estimated number using calibration data suggest that daily observer misclassification rates are higher than misclassification rates estimated from calibration data and prevent correction of the raw data. Our results illustrate the importance of testing for and quantifying observer error in species identification in wildlife census and population trend studies particularly when target species may be easily confused with other nontarget species.     

Landscape characteristics influence morphological and genetic differentiation in a widespread raptor (Buteo jamaicensis)

Landscape-scale population genetic structure in vagile vertebrates was commonly considered to be a contradiction in terms whereas recent studies have demonstrated behaviour and habitat associated structure in several such species. We investigate whether landscape features influence morphological and genetic differentiation in a widespread, mobile raptor. To accurately describe genetic differentiation associated with regional landscape factors, we first investigated subspecies relationships at a continental scale. We used 17 microsatellite loci and five morphological measurements to investigate differentiation between eastern and western subspecies of red-tailed hawks ( Buteo jamaicensis ) and to identify patterns between differentiation and habitat within western North America. Bayesian and frequency-based analyses of microsatellite data revealed clear distinctions between B. j. borealis (eastern) and B. j. calurus (western) samples. Furthermore, hawks sampled in Texas were stouter than those collected from the Rocky Mountains and farther west. Among western samples, birds from the Great Basin, Rocky Mountains, and Washington were significantly different in morphology than those from Oregon and California. We identified a pattern of isolation by distance among western breeding sites around the Sierra Nevada. Given the long-range dispersal capabilities of raptors, this pattern suggests that population-specific habitat preferences, corresponding with habitat breaks between eastern and western slopes of the Sierra Nevada, and/or regionally variable population densities limit migration between the Mediterranean habitat of central California and the xeric habitats of southern California and interior west. We suggest habitat preferences and regionally disparate population densities may play a role in shaping genetic structure in vagile avian taxa.     

Flight behaviour of sharp-shinned hawks during migration. II: Over water

The behaviour of sharp-shinned hawks (Accipiter striatus) confronted by water barriers was examined during fall migration at Cape May Point, new Jersey (Delaware Bay) and during spring migration at Whitefish Point, Michigan (Lake Suerior). Both study sites were at the end of long peninsulas where hawks must either cross approximately 18–24 km of water or fly hundreds of kilometres around the water barriers. Sharp-shinned hawks readily crossed at both sites when winds lateral (perpendicular) to crossing directions were light, but rarely when winds were strong, suggesting that the preferred to cross when the potential for being blown off course was minimal. A greater proportion of hawks also crossed when flight at the shoreline was at high as opposed to low altitudes, and when land on the opposite side of the water barrier was visible. At Cape May, hawks compensated for lateral winds of up to 6 m/s during flights over water, although very few birds attempted to cross when lateral winds exceeded 5 m/s. At Whitefish, hawks compensated only partially for lateral winds. The difference in realized flight direction between sites was attributable to differing topographies, not to a difference in the hawks' ability to compensate for lateral wind. It was hypothesized that there is a threshold for drift at lateral winds between 5 and 8 m/s for sharp-shinned hawks using powered flight over water.     

Lack of genetic differentiation between monarch butterflies with divergent migration destinations

Monarch butterflies are best known for their spectacular annual migration from eastern North America to Mexico. Monarchs also occur in the North American states west of the Rocky Mountains, from where they fly shorter distances to the California Coast. Whether eastern and western North American monarchs form one genetic population or are genetically differentiated remains hotly debated, and resolution of this debate is essential to understand monarch migration patterns and to protect this iconic insect species. We studied the genetic structure of North American migratory monarch populations, as well as nonmigratory populations in Hawaii and New Zealand. Our results show that eastern and western migratory monarchs form one admixed population and that monarchs from Hawaii and New Zealand have genetically diverged from North American butterflies. These findings suggest that eastern and western monarch butterflies maintain their divergent migrations despite genetic mixing. The finding that eastern and western monarchs form one genetic population also suggests that the conservation of overwintering sites in Mexico is crucial for the protection of monarchs in both eastern and western North America.     

Post-Pleistocene range expansion of the recently imperiled eastern little brown bat (Myotis lucifugus lucifugus) from a single southern refugium

Myotis lucifugus, once among the most widespread and common bats in North America, has been forecast to be extirpated east of the Rockies in as few as 16 years by the spread of white-nose syndrome. Recent genetic research has demonstrated that this species is paraphyletic and part of a broader species complex; however, only one lineage (Myotis lucifugus lucifugus [M. l. lucifugus]) is present in eastern North America. I used molecular tools and niche modeling to validate this and investigate the role that historical biogeography has played in the phylogenetic and population genetic structure of this species to determine if the eastern subspecies represents an evolutionarily distinct population.To establish the genetic structure within M. l. lucifugus, I densely sampled maternity colonies in Minnesota and sequenced 182 individuals for a portion of cytochrome b. Phylogenetic reconstruction and a haplotype network were used to infer the relationships among mitochondrial haplotypes. Population growth statistics were calculated to determine if there was evidence of significant expansion, and an environmental niche model (ENM) was constructed based on conditions during the last glacial maximum (LGM) to illustrate potential glacial refugia. All individuals derived from a single mitochondrial lineage. Genetic evidence points to population growth starting approximately 18 kya. ENM results show that there was likely a single large southern refugium extending across the southeastern United States and possibly several isolated refugia in western North America. Myotis lucifugus lucifugus likely maintained both a large range and a large population during the peaks of the glacial cycles, and its population appears to have expanded following the retreat of the Laurentide ice sheet. This imperiled lineage likely diverged in isolation from other members of the M. lucifugus/western long-eared Myotis during the Pleistocene.     

Phylogeography and mitochondrial diversity of extirpated brown bear (Ursus arctos) populations in the contiguous United States and Mexico

The fossil record indicates that the brown bear (Ursus arctos) colonized North America from Asia over 50 000 years ago. The species historically occupied the western United States and northern Mexico but has been extirpated from over 99% of this range in the last two centuries. To evaluate colonization hypotheses, subspecific classifications, and historical patterns and levels of genetic diversity in this region, we sequenced 229 nucleotides of the mitochondrial DNA control region in 108 museum specimens. The work was set in a global context by synthesizing all previous brown bear control region sequences from around the world. In mid-latitude North America a single moderately diverse clade is observed, represented by 23 haplotypes with up to 3.5% divergence. Only eight of 23 haplotypes (35%) are observed in the extensively sampled extant populations suggesting a substantial loss of genetic variability. The restriction of all haplotypes from mid-latitude North America to a single clade suggests that this region was founded by bears with a similar maternal ancestry. However, the levels and distributions of diversity also suggest that the colonizing population was not a small founder event, and that expansion occurred long enough ago for local mutations to accrue. Our data are consistent with recent genetic evidence that brown bears were south of the ice prior to the last glacial maximum. There is no support for previous subspecies designations, although bears of the southwestern United States may have had a distinctive, but recent, pattern of ancestry.     

Flight behaviour of sharp-shinned hawks during migration. I : Over land

We tested two hypotheses that have been proposed to explain why large numbers of sharpshinned hawks (Accipiter striatus) are counted during fall migration at Cape May Point, New Jersey. The most popular hypothesis, which suggests that hawks are drifted to the coast by west to northwest winds, was rejected in favour of the alternative hypothesis, which suggests that the large numbers of hawks seen on west winds resulted from a sampling bias. Using modified marine radar, we found that sharp-shinned hawks flew significantly lower at Cape May on days with west winds than on days with other winds, making them easier to count. The altitude of flight on days with other winds was regularly greater than 400 m, and hawks were difficult to detect without the radar. Migration traffic rates at Cape May were consistently greater than the broad-front migration rates computed from counts taken 36 km north and inland from Cape May. Flight directions measured at the inland site, away from topographic leading lines, showed that sharp-shinned hawks compensate for different wind directions by adjusting their headings, and the direction realized on all winds brings them to the coast. Our results suggest that counts of migrating hawks at some topographic features are subject to systematic biases and the conclusions derived from these counts may be erroneous.     

Response of a southern temperate marsupial, the Tasmanian pademelon (Thylogale billardierii), to historical and contemporary forest fragmentation

Despite only limited Pleistocene glacial activity in the southern hemisphere, temperate forest species experienced complex distributional changes resulting from the combined effects of glaciation, sea level change and increased aridity. The effects of these historical processes on population genetic structure are now overlain by the effects of contemporary habitat modification. In this study, 10 microsatellites and 629 bp of the mitochondrial control region were used to assess the effects of historical forest fragmentation and recent anthropogenic habitat change on the broad-scale population genetic structuring of a southern temperate marsupial, the Tasmanian pademelon. A total of 200 individuals were sampled from seven sites across Tasmania and two islands in Bass Strait. High mitochondrial and nuclear genetic diversity indicated the maintenance of large historical population sizes. There was weak phylogeographical structuring of haplotypes, although all King Island haplotypes and three Tasmanian haplotypes formed a divergent clade implying the mid-Pleistocene isolation of a far northwestern population. Both the mitochondrial and nuclear data indicated a division of Tasmanian populations into eastern and western regions. This was consistent with a historical barrier resulting from increased aridity in the lowland 'midlands' region during glacial periods, and with a contemporary barrier resulting from recent habitat modification in that region. In Tasmania, gene flow appears to have been relatively unrestricted during glacial maxima in the west, while in the east there was evidence for historical expansion from at least one large glacial refuge and recolonization of Flinders Island.     

Combining genetic markers and stable isotopes to reveal population connectivity and migration patterns in a neotropical migrant,Wilson's warbler (Wilsonia pusilla)

We used results from the analysis of microsatellite DNA variation and hydrogen stable-isotope ratios to characterize the population structure of a neotropical migrant passerine, the Wilson's warbler (Wilsonia pusilla). The resulting information was then used to infer migration patterns and population connectivity between breeding grounds in North America and overwintering areas in Mexico and Central America. The microsatellite data revealed genetic structure across the North American continent; populations in the west were found to significantly differ from the east. Minimal genetic structure was observed among western sites. The lack of isolation by distance and low variance in FST values suggests that gene flow could play an ongoing role in limiting genetic differentiation among sites in the western part of the distribution. However, additional information including estimates of effective population size and the proximity of the population to equilibrium is required before the role of gene flow can be assessed fully. Analysis of isotope data showed a negative relationship between latitude and hydrogen isotope ratios in breeding ground individuals. There was a positive relationship between wintering ground latitude and hydrogen isotope ratios for individuals that were genetically western in origin. This is consistent with a leapfrog pattern of migration, in which genetically western birds from the northernmost breeding areas overwinter at the most southerly locations in Central America. Additionally, isotopic ratios of western birds suggest that coastal breeders overwinter in western Mexico, while western birds from further inland and at high elevations overwinter in eastern Mexico. Using information from both genetic an isotopic approaches will probably be useful for identifying patterns of migration and population connectivity between breeding and overwintering areas, both important issues for conservation efforts, and may also contribute to investigation of the evolution of migration.     

High migration rates shape the postglacial history of amphi‐Atlantic bryophytes

Paleontological evidence and current patterns of angiosperm species richness suggest that European biota experienced more severe bottlenecks than North American ones during the last glacial maximum. How well this pattern fits other plant species is less clear. Bryophytes offer a unique opportunity to contrast the impact of the last glacial maximum in North America and Europe because about 60% of the European bryoflora is shared with North America. Here, we use population genetic analyses based on approximate Bayesian computation on eight amphi‐Atlantic species to test the hypothesis that North American populations were less impacted by the last glacial maximum, exhibiting higher levels of genetic diversity than European ones and ultimately serving as a refugium for the postglacial recolonization of Europe. In contrast with this hypothesis, the best‐fit demographic model involved similar patterns of population size contractions, comparable levels of genetic diversity and balanced migration rates between European and North American populations. Our results thus suggest that bryophytes have experienced comparable demographic glacial histories on both sides of the Atlantic. Although a weak, but significant genetic structure was systematically recovered between European and North American populations, evidence for migration from and towards both continents suggests that amphi‐Atlantic bryophyte population may function as a metapopulation network. Reconstructing the biogeographic history of either North American or European bryophyte populations therefore requires a large, trans‐Atlantic geographic framework.     

Refugia in the Cordilleran ice sheet of western North America: chloroplast DNA diversity in the Arctic–alpine plant Oxyria digyna

Aim  Late Pleistocene ice sheets are thought to have covered most of western Canada, including all of British Columbia (BC). We examine patterns of genetic variation in an Arctic–alpine plant to evaluate the possibility of full glacial refugia within the area covered by the Cordilleran ice sheet (CIS) and to uncover post-glacial migration routes.
Location  Western North America.
Methods  We sampled 1030 individuals of the Arctic–alpine plant Oxyria digyna from 117 populations distributed over much of its range in western and northern North America. DNA haplotypes were identified using restriction site analysis of two chloroplast DNA intergene spacer regions, psb A- trn H and trn T-L. We examined the geographical distribution of haplotype diversity in relation to latitude, and also compared various indices of diversity in putatively glaciated and unglaciated regions. Patterns of migration were inferred using nested clade analysis.
Results  We detected a total of 20 haplotypes. High haplotype diversity was found in Beringia, in unglaciated western USA, and in northern BC at 57–59° N, well within the accepted limits of the CIS. Ancestral haplotypes were also centred in northern BC.
Main conclusions  High genetic diversity of Oxyria digyna is expected in unglaciated regions, but unexpected in northern BC if British Columbia was entirely covered by ice during the late Pleistocene. Our observations suggest the presence of unglaciated areas providing late Pleistocene refugia in northern BC. Such refugia would have important implications for the origins and migrations of many plant and animal species in north-western North America.     

The predatory behavior of wintering <Emphasis Type="Italic">Accipiter</Emphasis> hawks: temporal patterns in activity of predators and prey

Studies focused on how prey trade-off predation and starvation risk are prevalent in behavioral ecology. However, our current understanding of these trade-offs is limited in one key respect: we know little about the behavior of predators. In this study, we provide some of the first detailed information on temporal patterns in the daily hunting behavior of bird-eating Accipiter hawks and relate that to their prey. During the winters of 1999–2004, twenty-one sharp-shinned hawks (A. striatus) and ten Cooper’s hawks (A. cooperii) were intensively radio tracked in rural and urban habitats in western Indiana, USA. Cooper’s hawks left roost before sunrise and usually returned to roost around sunset, while sharp-shinned hawks left roost at sunrise or later and returned to roost well before sunset. An overall measure of Cooper’s-hawk-induced risk (a composite variable of attack rate and activity patterns) generally reflected the timing of prey activity, with peaks occurring around sunrise and sunset. In contrast, risk induced by the smaller sharp-shinned hawk did not strongly reflect the activity of their prey. Specifically, an early morning peak in prey activity did not correspond to a period with intense hawk activity. The lack of early morning hunting by sharp-shinned hawks may reflect the high risk of owl-induced predation experienced by these hawks. The net effect of this intraguild predation may be to “free” small birds from much hawk-induced predation risk prior to sunrise. This realization presents an alternative to energetics as an explanation for the early morning peak in small bird activity during the winter.     

Genetic consequences of Pleistocene glaciations for the tundra vole (Microtus oeconomus) in Beringia

Repeated glacial events during the Pleistocene fragmented and displaced populations throughout the northern continents. Different models of the effects of these climate-driven events predict distinct phylogeographic and population genetic outcomes for high-latitude faunas. The role of glaciations in (i) promoting intraspecific genetic differentiation and (ii) influencing genetic diversity was tested within a phylogeographic framework using the rodent Microtus oeconomus. The spatial focus for the study was Beringia, which spans eastern Siberia and northwestern North America, and was a continental crossroads and potential high arctic refugium during glaciations. Variation in mitochondrial DNA (cytochrome b and control region; 214 individuals) and nuclear DNA (ALDH1 intron; 63 individuals) was investigated across the Beringian region. Close genetic relationships among populations on either side of the Bering Strait are consistent with a history of periodic land connections between North America and Asia. A genetic discontinuity observed in western Beringia between members of a Central Asian clade and a Beringian clade is geographically congruent with glacial advances and with phylogeographic discontinuities identified in other organisms. Divergent island populations in southern Alaska were probably initially isolated by glacial vicariance, but subsequent differentiation has resulted from insularity. Tests of the genetic effects of postglacial colonization were largely consistent with expansion accompanied by founder effect bottlenecking, which yields reduced diversity in populations from recently deglaciated areas. Evidence that populations in the Beringian clade share a history of expansion from a low-diversity ancestral population suggests that Beringia was colonized by a small founder population from central Asia, which subsequently expanded in isolation.     

Development of 19 microsatellite loci for Swainson's hawks (Buteo swainsoni) and other buteos

We developed 26 Swainson's hawk (Buteo swainsoni) microsatellite primers from CA, AAT, CATC and GAGAA enriched genomic libraries. Primers were tested in 357 Swainson's hawks from western North America as well as seven other Buteo species. These markers will have broad application in investigations of Buteo population structure and genetic diversity.     

Multilocus phylogeography and population structure of common eiders breeding in North America and Scandinavia

Aim Glacial refugia during the Pleistocene had major impacts on the levels and spatial apportionment of genetic diversity of species in northern latitude ecosystems. We characterized patterns of population subdivision, and tested hypotheses associated with locations of potential Pleistocene refugia and the relative contribution of these refugia to the post‐glacial colonization of North America and Scandinavia by common eiders (Somateria mollissima). Specifically, we evaluated localities hypothesized as ice‐free areas or glacial refugia for other Arctic vertebrates, including Beringia, the High Arctic Canadian Archipelago, Newfoundland Bank, Spitsbergen Bank and north‐west Norway. Location Alaska, Canada, Norway and Sweden. Methods Molecular data from 12 microsatellite loci, the mitochondrial DNA (mtDNA) control region, and two nuclear introns were collected and analysed for 15 populations of common eiders (n = 716) breeding throughout North America and Scandinavia. Population genetic structure, historical population fluctuations and gene flow were inferred using F‐statistics, analyses of molecular variance, and multilocus coalescent analyses. Results Significant inter‐population variation in allelic and haplotypic frequencies were observed (nuclear DNA F_ST = 0.004–0.290; mtDNA Φ_ST = 0.051–0.927). Whereas spatial differentiation in nuclear genes was concordant with subspecific designations, geographic proximity was more predictive of inter‐population variance in mitochondrial DNA haplotype frequency. Inferences of historical population demography were consistent with restriction of common eiders to four geographic areas during the Last Glacial Maximum: Belcher Islands, Newfoundland Bank, northern Alaska and Svalbard. Three of these areas coincide with previously identified glacial refugia: Newfoundland Bank, Beringia and Spitsbergen Bank. Gene‐flow and clustering analyses indicated that the Beringian refugium contributed little to common eider post‐glacial colonization of North America, whereas Canadian, Scandinavian and southern Alaskan post‐glacial colonization is likely to have occurred in a stepwise fashion from the same glacial refugium. Main conclusions Concordance of proposed glacial refugia used by common eiders and other Arctic species indicates that Arctic and subarctic refugia were important reservoirs of genetic diversity during the Pleistocene. Furthermore, suture zones identified at MacKenzie River, western Alaska/Aleutians and Scandinavia coincide with those identified for other Arctic vertebrates, suggesting that these regions were strong geographic barriers limiting dispersal from Pleistocene refugia.     

Genetic structure and the North American postglacial expansion of the barnacle, Semibalanus balanoides

Population genetic characteristics are shaped by the life-history traits of organisms and the geologic history of their habitat. This study provides a neutral framework for understanding the population dynamics and opportunities for selection in Semibalanus balanoides, a species that figures prominently in ecological and evolutionary studies in the Atlantic intertidal. We used mitochondrial DNA (mtDNA) control region (N = 131) and microsatellite markers (～40 individuals/site/locus) to survey populations of the broadly dispersing acorn barnacle from 8 sites spanning 800 km of North American coast and 1 site in Europe. Patterns of mtDNA sequence evolution were consistent with larger population sizes in Europe and population expansion at the conclusion of the last ice age, approximately 20?000 years ago, in North America. A significant portion of mitochondrial diversity was partitioned between the continents (?(ST) = 0.281), but there was only weak structure observed from mtDNA within North America. Microsatellites showed significant structuring between the continents (F(ST) = 0.021) as well as within North America (F(ST) = 0.013). Isolation by distance in North America was largely driven by a split between populations south of Cape Cod and all others (P < 10(-4)). The glacial events responsible for generating allelic diversity at mtDNA and microsatellites may also be responsible for generating selectable variation at metabolic enzymes in S. balanoides.     

Contradictions and Concordances in American Colonization Models

The traditional view of American colonization during the late Pleistocene has largely been conditioned on early conceptions of the timing and extent of continental glaciations and the age and distribution of archeological sites. A review of newer, high resolution genetic data, both from modern populations and ancient DNA samples, along with the emergence of several early archeological sites in both North and South America, and reconsiderations of the glacial dynamics in North America indicate that some aspects of the traditional view need reconsideration. It seems obvious from archeological data that a preglacial occupation of the Americas needs to be closely examined. Accumulating molecular genetic data raises new questions about the timing and population size of the initial colonization(s), while a closer examination of glacial models suggests that a number of routes into the Americas may have been available until fairly late in the last glacial cycle.     

Mitochondrial DNA evolution in the Anaxyrus boreas species group

The Anaxyrus boreas species group currently comprises four species in western North America including the broadly distributed A. boreas, and three localized species, Anaxyrus nelsoni, Anaxyrusexsul and Anaxyrus canorus. Phylogenetic analyses of the mtDNA 12S rDNA, cytochrome oxidase I, control region, and restriction sites data, identified three major haplotype clades. The Northwest clade (NW) includes both subspecies of A. boreas and divergent minor clades in the middle Rocky Mountains, coastal, and central regions of the west and Pacific Northwest. The Southwest (SW) clade includes A. exsul, A. nelsoni, and minor clades in southern California. Anaxyrus canorus, previously identified as paraphyletic, has populations in both the NW and SW major clades. The Eastern major clade (E) includes three divergent lineages from southern Utah, the southern Rocky Mountains, and north of the Great Basin at the border of Utah and Nevada. These results identify new genetic variation in the eastern portion of the toad's range and are consistent with previous regional studies from the west coast. Low levels of control region sequence divergence between major clades (2.2-4.7% uncorrected pair-wise distances) are consistent with Pleistocene divergence and suggest that the phylogeographic history of the group was heavily influenced by dynamic Pleistocene glacial and climatic changes, and especially pluvial changes, in western North America. Results reported here may impact conservation plans in that the current taxonomy does not reflect the diversity in the group.     

Genetic evidence for a single stock of the deep-sea teleost Beryx decadactylus in the North Atlantic Ocean as inferred from mtDNA control region analysis

Mitochondrial control region sequences of 141 alfonsino Beryx decadactylus sampled off the coast of South Carolina were compared with 164 sequences from B. decadactylus collected in the Azores for inferring population structure and demographic history of this deep-water teleost in the North Atlantic Ocean. Analysis of molecular variance showed that 100% of the genetic variation was found within populations, indicating an absence of population structure (Φ(ST) = -0· 003). Neutrality tests and mismatch distribution analyses of pooled sequences suggested that B. decadactylus in the North Atlantic Ocean have undergone population expansion. These results may indicate that transatlantic gene flow occurs, possibly through passive drift of larvae or adult migration. The potential of a shared stock between the eastern and western North Atlantic Ocean will need to be considered if a directed fishery for B. decadactylus were to develop in the U.S.A.