scholarly journals Variation in global distribution, population structures, and demographic history for four Trichiurus cutlassfishes

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12639
Author(s):  
Hsiu-Chin Lin ◽  
Chia-Jung Tsai ◽  
Hui-Yu Wang
Keyword(s):  
Population Structure ◽  
Phylogenetic Trees ◽  
Sequence Data ◽  
Demographic History ◽  
Ice Age ◽  
Fish Stock ◽  
Ecological Niches ◽  
Specific Information ◽  
Similar Species ◽  
Haplotype Networks

Background Species-specific information on distribution and demographic patterns provides important implications for conservation and fisheries management. However, such information is often lacking for morphologically-similar species, which may lead to biases in the assessments of these species and even decrease effort towards sustainable management. Here, we aimed to uncover the distribution range, population structure and demographic history for four exploited Trichiurus cutlassfishes using genetics. These cutlassfishes contribute substantial global fisheries catch, with a high proportion of catch harvested from the NW Pacific. Methods We chose the widely available mitochondrial 16S ribosomal RNA (16S) as the genetic marker for cutlassfishes. We compiled the 16S sequence data from both the GenBank and a survey of trawler catch samples along the NW Pacific coasts 22–39°N. Genealogical relationships within each species was visualized with haplotype networks and potential population differentiations were further evaluated with AMOVA. Demographic histories were estimated using neutrality test, mismatch analysis, and the Bayesian skyline plot. The reconstructed phylogenetic trees were used to delimit and estimate the divergence time of species and included populations. Results In each of two cosmopolitan species, T. lepturus and T. nanhaiensis, we observed distinct populations along the coasts of warm oceans; such population differentiation might result from historical geographic barriers in the Pleistocene. In the NW Pacific, four Trichiurus species vary in their distribution habitats, which reflect differential ecological niches among these species. The small-sized T. brevis are primarily found in nearshore habitats; the warm-affiliated T. nanhaiensis are present along the path of the Kuroshio Current; the cold-affiliated T. japonicus spatially diverged from the widely-distributed T. lepturus, with the latter mainly occupy in warmer regions. Despite these differences, a single well-mixing fish stock, thus one management unit, was identified in each of the four species, presumably due to expansion of their population sizes predated the Last Glacial Maximum and a lack of distribution barrier. The most dominant T. japonicus, which have at least one magnitude higher effective population size than the others, show a unique abrupt size expansion event at 75 to 50-kilo years ago when the low sea level occurred during the ice age. Main conclusions The demographic history revealed by our genetic analyses advances understanding of the current distribution and population structure for these congeneric species. Moreover, the uncovered population structure provides insight into the assessment and management of these species. Such information complements contemporary knowledge about these species and enables us to forecast their ability to resist future environmental and anthropogenic disturbances.

scholarly journals Ecological opportunities and specializations shaped genetic divergence in a highly mobile marine top predator

2014 ◽  
Vol 281 (1795) ◽  
pp. 20141558 ◽  
Author(s):  
Marie Louis ◽  
Michael C. Fontaine ◽  
Jérôme Spitz ◽  
Erika Schlund ◽  
Willy Dabin ◽  
...  
Keyword(s):  
Population Structure ◽  
Mediterranean Sea ◽  
Environmental Changes ◽  
Demographic History ◽  
World Ocean ◽  
Ecological Niches ◽  
Morphological Divergence ◽  
Evolutionary Diversification ◽  
The Mediterranean ◽  
Population Demographic

Environmental conditions can shape genetic and morphological divergence. Release of new habitats during historical environmental changes was a major driver of evolutionary diversification. Here, forces shaping population structure and ecotype differentiation (‘pelagic’ and ‘coastal’) of bottlenose dolphins in the North-east Atlantic were investigated using complementary evolutionary and ecological approaches. Inference of population demographic history using approximate Bayesian computation indicated that coastal populations were likely founded by the Atlantic pelagic population after the Last Glacial Maxima probably as a result of newly available coastal ecological niches. Pelagic dolphins from the Atlantic and the Mediterranean Sea likely diverged during a period of high productivity in the Mediterranean Sea. Genetic differentiation between coastal and pelagic ecotypes may be maintained by niche specializations, as indicated by stable isotope and stomach content analyses, and social behaviour. The two ecotypes were only weakly morphologically segregated in contrast to other parts of the World Ocean. This may be linked to weak contrasts between coastal and pelagic habitats and/or a relatively recent divergence. We suggest that ecological opportunity to specialize is a major driver of genetic and morphological divergence. Combining genetic, ecological and morphological approaches is essential to understanding the population structure of mobile and cryptic species.

scholarly journals Genetic diversity and population structure of Rhipicephalus sanguineus sensu lato across different regions of Colombia

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Luisa Páez-Triana ◽  
Marina Muñoz ◽  
Giovanny Herrera ◽  
Darwin A. Moreno-Pérez ◽  
Gabriel A. Tafur-Gómez ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Dna Sequences ◽  
Phylogenetic Trees ◽  
Statistical Tests ◽  
Population Expansion ◽  
Rhipicephalus Sanguineus ◽  
Tick Population ◽  
12S Rdna ◽  
Haplotype Networks

Abstract Background There has been a long-standing debate over the taxonomic status of Rhipicephalus sanguineus sensu lato. Different studies worldwide have reported the occurrence of different well-defined lineages, in addition to Rhipicephalus sanguineus sensu stricto. To date, there are very few studies examining the diverse aspects of this tick in Colombia. We assessed the population structure and genetic diversity of R. sanguineus s.l. in eight departmental regions across Colombia. Methods A total of 170 ticks were collected from dogs in different departments of Colombia. All specimens were morphologically compatible with R. sanguineus s.l. and subjected to genetic analysis. DNA sequences were obtained for the 12S rDNA, cytochrome oxidase I (COI) and internal transcribed spacer 2 (ITS2) markers. A concatenated set of all mitochondrial markers was also constructed. Next, maximum likelihood phylogenetic trees were constructed using the sequences generated herein and sequences available in GenBank. Finally, we assessed different summary statistics and analysed population structure and divergence with Fst and Dxy and demographic changes with Tajima's D and Fu and Li’s statistical tests. Results Analysis of the 12S rDNA and COI revealed that all R. sanguineus s.l. specimens collected across different regions of Colombia clustered within the tropical lineage. Micro-geographical analyses showed that the tick population from Amazonas formed a distinct cluster separated from the other sequences, with moderate Fst and Dxy values. However, no signs of a robust population structure were found within the country. The results of Fu’s FS tests, together with the haplotype networks and diversity values, signal a possible population expansion of this tick species in Colombia. Conclusions Evidence provided herein supports the tropical lineage as the main circulating lineage in Colombia, exhibiting a general lack of genetic structure except for the Amazonas region. Graphical Abstract

scholarly journals Solving the taxonomic identity of Pseudotomentella tristis s.l. (Thelephorales, Basidiomycota) – a multi-gene phylogeny and taxonomic review, integrating ecological and geographical data

MycoKeys ◽  
2019 ◽  
Vol 50 ◽  
pp. 1-77 ◽  
Author(s):  
Sten Svantesson ◽  
Karl-Henrik Larsson ◽  
Urmas Kõljalg ◽  
Tom W. May ◽  
Patrik Cangren ◽  
...  
Keyword(s):  
Sequence Data ◽  
Distinct Species ◽  
The Arctic ◽  
Root Tip ◽  
Ecological Niches ◽  
Similar Species ◽  
Gene Trees ◽  
Species Trees ◽  
Type Specimens ◽  
Wide Range

P.tristisis an ectomycorrhizal, corticioid fungus whose name is frequently assigned to collections of basidiomata as well as root tip and soil samples from a wide range of habitats and hosts across the northern hemisphere. Despite this, its identity is unclear; eight heterotypic taxa have in major reviews of the species been considered synonymous with or morphologically similar toP.tristis, but no sequence data from type specimens have been available.With the aim to clarify the taxonomy, systematics, morphology, ecology and geographical distribution ofP.tristisand its morphologically similar species, we studied their type specimens as well as 147 basidiomata collections of mostly North European material.We used gene trees generated in BEAST 2 and PhyML and species trees estimated in STACEY and ASTRAL to delimit species based on the ITS, LSU, Tef1α and mtSSU regions. We enriched our sampling with environmental ITS sequences from the UNITE database.We found theP.tristisgroup to contain 13 molecularly and morphologically distinct species. Three of these,P.tristis,P.umbrinaandP.atrofusca, are already known to science, while ten species are here described as new:P.sciastrasp. nov.,P.tristoidessp. nov.,P.umbrinascenssp. nov.,P.pinophilasp. nov.,P.alnophilasp. nov.,P.alobatasp. nov.,P.plurilobasp. nov.,P.abundilobasp. nov.,P.rotundisporasp. nov.andP.mediasp. nov.We discoveredP.rhizopunctataandP.atrofuscato form a sister clade to all other species inP.tristiss.l. These two species, unlike all other species in theP.tristiscomplex, are dimitic.In this study, we designate epitypes forP.tristis,P.umbrinaandHypochnopsisfuscataand lectotypes forAuriculariaphylacterisandThelephorabiennis. We show that the holotype ofHypochnussitnensisand the lectotype ofHypochnopsisfuscataare conspecific withP.tristis, but in the absence of molecular information we regardPseudotomentellalongisterigmataandHypochnusrhacodiumas doubtful taxa due to their aberrant morphology. We confirmA.phylacteris,TomentellabiennisandSeptobasidiumarachnoideumas excluded taxa, since their morphology clearly show that they belong to other genera. A key to the species of theP.tristisgroup is provided.We foundP.umbrinato be a common species with a wide, Holarctic distribution, forming ectomycorrhiza with a large number of host species in habitats ranging from tropical forests to the Arctic tundra. The other species in theP.tristisgroup were found to be less common and have narrower ecological niches.

scholarly journals A first investigation into the evolutionary relationships, population structure and demographic history of New Zealand Trevally (Pseudocaranx georgianus) and its implications for fisheries management

2021 ◽  
Author(s):  
◽  
Leah Kemp
Keyword(s):  
Population Structure ◽  
New Zealand ◽  
Western Australia ◽  
Sequence Data ◽  
Demographic History ◽  
Population Expansion ◽  
Whole Genome Sequence ◽  
Coi Gene ◽  
P Value

<p>Pseudocaranx georgianus is a commercially important fishery in New Zealand. Currently, the management of this fishery assumes that Quota Management Areas comprise single biological stocks of a single species. However, little is known regarding the population structure of New Zealand P. georgianus and morphological data suggests that a cryptic Pseudocaranx species is included within these fisheries.  Whole genome sequence data was used to assemble and describe the first P. georgianus mitogenome. Primers were developed to produce the first genetic sequence data for New Zealand P. georgianus. The cytochrome c oxidase subunit I (COI) gene was sequenced for fourteen P. georgianus from New Zealand waters. These were compared phylogenetically with existing COI sequence data for P. georgianus from Australia and other Pseudocaranx species from a world-wide distribution. The hyper-variable control region of 304 P. georgianus sampled throughout New Zealand’s North Island and 68 P. georgianus from three locations in Western Australia were also sequenced. These sequences were used to explore the population structure and demographic history of New Zealand P. georgianus using haplotype networks, AMOVA’s, genetic diversity measures, Tajima’s D, Fu’s F and Bayesian migration analyses.  The P. georgianus mitogenome is typical of Cartilaginous fish species showing no major gene rearrangements, typical gene region lengths and stop and start codons. While assembling the P. georgianus mitogenome, this thesis demonstrates the importance of key methodological choices made when assembling mitogenomes from whole genome sequence data in silco in Geneious version 11.1. The choice of reference mitogenome has the largest influence on the quality of the assembly, impacting the annotation of the final mitogenome and the resolution of uncertain DNA regions. Increasing the number of mapping iterations increased the quality of the assembly but has a limited ability to mitigate the effects of using a poor reference mitogenome. Overall, I demonstrate the need to investigate and report the quality of published mitogenomes.   All Pseudocaranx species were monophyletic on the COI gene, supporting the current taxonomy of the Pseudocaranx complex. P. georgianus from Western Australia and New Zealand’s North Island represent a monophyletic clade pending a taxonomic verification that two Pseudocaranx dentex sampled in Australia are in fact P. georgianus.   No evidence was found to suggest that either of the New Zealand or Western Australian populations of P. georgianus are isolated by distance or clearly structured as distinct stocks. However, some populations of New Zealand P. georgianus were genetically distinct, including fish sampled from Raglan and the Bay of Plenty (FST of 0.02698 (p-value: 0.00901+-0.0091) as well as the North Cape and North Taranaki Bight (FST: 0.02698, p-value: 0.00901+-0.0091).   Some evidence was found to support the claim that P. georgianus along the west coast of New Zealand’s North Island is structured and no evidence was found to refute the claim that fish from the Bay of Plenty are the same biological stock as fish from TRE2. Highly divergent control region sequences of fish sampled from Three Kings Islands and the Kermadec Islands suggest that these fish could be a species distinct from P. georgianus. Two genetically distinct populations of P. georgianus were identified in New Zealand’s North Island and Western Australia (FST: 0.03517, p-value < 0.001), but further research would be required to determine if they are distinct species or populations. One juvenile population sampled in Whangarei had a high level of genetic connectivity with adult P. georgianus throughout New Zealand’s North Island, likely reflecting the batch spawning and occasional long-distance migration behaviour of P. georgianus.  Negative Tajima’s D and Fu’s F statistics (D: -1.50612, p-value: 0.018; F: -23.54376, p-value: 0.011), unimodal mismatch distributions and skyline plots indicate that the New Zealand P. georgianus population has undergone a population expansion, possibly resulting from a geographic range expansion.The Western Australian population may also have undergone a population expansion (D: -1.27903, p-value: 0.086; F: -24.11497, p-value < 0.00001). However, a multimodal mismatch distribution (Harpending’s Raggedness index: 0.00454591, p-value: 0.02) indicated that there is some stability in the size of this population.   This thesis is a first genetic investigation into New Zealand P. georgianus and has provided important biological insights into this species. Valuable information is revealed which will inform the management of New Zealand P. georgianus fisheries as inputs for stock assessment models. Additionally, several future research directions have been revealed which will further extend our knowledge of this taonga. For example, future genetic and taxonomic analyses may reveal a cryptic Pseudocaranx species occurring in the Three Kings and Kermadec Islands.</p>

scholarly journals A first investigation into the evolutionary relationships, population structure and demographic history of New Zealand Trevally (Pseudocaranx georgianus) and its implications for fisheries management

2021 ◽  
Author(s):  
◽  
Leah Kemp
Keyword(s):  
Population Structure ◽  
New Zealand ◽  
Western Australia ◽  
Sequence Data ◽  
Demographic History ◽  
Population Expansion ◽  
Whole Genome Sequence ◽  
Coi Gene ◽  
P Value

<p>Pseudocaranx georgianus is a commercially important fishery in New Zealand. Currently, the management of this fishery assumes that Quota Management Areas comprise single biological stocks of a single species. However, little is known regarding the population structure of New Zealand P. georgianus and morphological data suggests that a cryptic Pseudocaranx species is included within these fisheries.  Whole genome sequence data was used to assemble and describe the first P. georgianus mitogenome. Primers were developed to produce the first genetic sequence data for New Zealand P. georgianus. The cytochrome c oxidase subunit I (COI) gene was sequenced for fourteen P. georgianus from New Zealand waters. These were compared phylogenetically with existing COI sequence data for P. georgianus from Australia and other Pseudocaranx species from a world-wide distribution. The hyper-variable control region of 304 P. georgianus sampled throughout New Zealand’s North Island and 68 P. georgianus from three locations in Western Australia were also sequenced. These sequences were used to explore the population structure and demographic history of New Zealand P. georgianus using haplotype networks, AMOVA’s, genetic diversity measures, Tajima’s D, Fu’s F and Bayesian migration analyses.  The P. georgianus mitogenome is typical of Cartilaginous fish species showing no major gene rearrangements, typical gene region lengths and stop and start codons. While assembling the P. georgianus mitogenome, this thesis demonstrates the importance of key methodological choices made when assembling mitogenomes from whole genome sequence data in silco in Geneious version 11.1. The choice of reference mitogenome has the largest influence on the quality of the assembly, impacting the annotation of the final mitogenome and the resolution of uncertain DNA regions. Increasing the number of mapping iterations increased the quality of the assembly but has a limited ability to mitigate the effects of using a poor reference mitogenome. Overall, I demonstrate the need to investigate and report the quality of published mitogenomes.   All Pseudocaranx species were monophyletic on the COI gene, supporting the current taxonomy of the Pseudocaranx complex. P. georgianus from Western Australia and New Zealand’s North Island represent a monophyletic clade pending a taxonomic verification that two Pseudocaranx dentex sampled in Australia are in fact P. georgianus.   No evidence was found to suggest that either of the New Zealand or Western Australian populations of P. georgianus are isolated by distance or clearly structured as distinct stocks. However, some populations of New Zealand P. georgianus were genetically distinct, including fish sampled from Raglan and the Bay of Plenty (FST of 0.02698 (p-value: 0.00901+-0.0091) as well as the North Cape and North Taranaki Bight (FST: 0.02698, p-value: 0.00901+-0.0091).   Some evidence was found to support the claim that P. georgianus along the west coast of New Zealand’s North Island is structured and no evidence was found to refute the claim that fish from the Bay of Plenty are the same biological stock as fish from TRE2. Highly divergent control region sequences of fish sampled from Three Kings Islands and the Kermadec Islands suggest that these fish could be a species distinct from P. georgianus. Two genetically distinct populations of P. georgianus were identified in New Zealand’s North Island and Western Australia (FST: 0.03517, p-value < 0.001), but further research would be required to determine if they are distinct species or populations. One juvenile population sampled in Whangarei had a high level of genetic connectivity with adult P. georgianus throughout New Zealand’s North Island, likely reflecting the batch spawning and occasional long-distance migration behaviour of P. georgianus.  Negative Tajima’s D and Fu’s F statistics (D: -1.50612, p-value: 0.018; F: -23.54376, p-value: 0.011), unimodal mismatch distributions and skyline plots indicate that the New Zealand P. georgianus population has undergone a population expansion, possibly resulting from a geographic range expansion.The Western Australian population may also have undergone a population expansion (D: -1.27903, p-value: 0.086; F: -24.11497, p-value < 0.00001). However, a multimodal mismatch distribution (Harpending’s Raggedness index: 0.00454591, p-value: 0.02) indicated that there is some stability in the size of this population.   This thesis is a first genetic investigation into New Zealand P. georgianus and has provided important biological insights into this species. Valuable information is revealed which will inform the management of New Zealand P. georgianus fisheries as inputs for stock assessment models. Additionally, several future research directions have been revealed which will further extend our knowledge of this taonga. For example, future genetic and taxonomic analyses may reveal a cryptic Pseudocaranx species occurring in the Three Kings and Kermadec Islands.</p>

scholarly journals Uncovering epidemiological dynamics in heterogeneous host populations using phylogenetic methods

2013 ◽  
Vol 368 (1614) ◽  
pp. 20120198 ◽  
Author(s):  
Tanja Stadler ◽  
Sebastian Bonhoeffer
Keyword(s):  
Population Structure ◽  
Phylogenetic Trees ◽  
Sequence Data ◽  
Intravenous Drug User ◽  
Host Population ◽  
Major Influence ◽  
Parameter Estimates ◽  
Sexually Transmitted ◽  
Sex With Men ◽  
The Impact

Host population structure has a major influence on epidemiological dynamics. However, in particular for sexually transmitted diseases, quantitative data on population contact structure are hard to obtain. Here, we introduce a new method that quantifies host population structure based on phylogenetic trees, which are obtained from pathogen genetic sequence data. Our method is based on a maximum-likelihood framework and uses a multi-type branching process, under which each host is assigned to a type (subpopulation). In a simulation study, we show that our method produces accurate parameter estimates for phylogenetic trees in which each tip is assigned to a type, as well for phylogenetic trees in which the type of the tip is unknown. We apply the method to a Latvian HIV-1 dataset, quantifying the impact of the intravenous drug user epidemic on the heterosexual epidemic (known tip states), and identifying superspreader dynamics within the men-having-sex-with-men epidemic (unknown tip states).

scholarly journals PSI-40 Two mitochondrial lineages revealed in North American yak

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 477-477
Author(s):  
Leah K Treffer ◽  
Edward S Rice ◽  
Anna M Fuller ◽  
Samuel Cutler ◽  
Jessica L Petersen
Keyword(s):  
Sequence Data ◽  
Haplotype Network ◽  
Ovis Aries ◽  
Similar Species ◽  
Nucleotide Polymorphisms ◽  
Mt Dna ◽  
Protein Coding ◽  
Sister Clade ◽  
Mtdna Sequence ◽  
The Impact

Abstract Domestic yak (Bos grunniens) are bovids native to the Asian Qinghai-Tibetan Plateau. Studies of Asian yak have revealed that introgression with domestic cattle has contributed to the evolution of the species. When imported to North America (NA), some hybridization with B. taurus did occur. The objective of this study was to use mitochondrial (mt) DNA sequence data to better understand the mtDNA origin of NA yak and their relationship to Asian yak and related species. The complete mtDNA sequence of 14 individuals (12 NA yak, 1 Tibetan yak, 1 Tibetan B. indicus) was generated and compared with sequences of similar species from GeneBank (B. indicus, B. grunniens (Chinese), B. taurus, B. gaurus, B. primigenius, B. frontalis, Bison bison, and Ovis aries). Individuals were aligned to the B. grunniens reference genome (ARS_UNL_BGru_maternal_1.0), which was also included in the analyses. The mtDNA genes were annotated using the ARS-UCD1.2 cattle sequence as a reference. Ten unique NA yak haplotypes were identified, which a haplotype network separated into two clusters. Variation among the NA haplotypes included 93 nonsynonymous single nucleotide polymorphisms. A maximum likelihood tree including all taxa was made using IQtree after the data were partitioned into twenty-two subgroups using PartitionFinder2. Notably, six NA yak haplotypes formed a clade with B. indicus; the other four haplotypes grouped with B. grunniens and fell as a sister clade to bison, gaur and gayal. These data demonstrate two mitochondrial origins of NA yak with genetic variation in protein coding genes. Although these data suggest yak introgression with B. indicus, it appears to date prior to importation into NA. In addition to contributing to our understanding of the species history, these results suggest the two major mtDNA haplotypes in NA yak may functionally differ. Characterization of the impact of these differences on cellular function is currently underway.

scholarly journals An Integrated Framework for the Inference of Viral Population History From Reconstructed Genealogies

Genetics ◽  
2000 ◽  
Vol 155 (3) ◽  
pp. 1429-1437
Author(s):  
Oliver G Pybus ◽  
Andrew Rambaut ◽  
Paul H Harvey
Keyword(s):  
Maximum Likelihood ◽  
Sequence Data ◽  
Demographic History ◽  
Population History ◽  
Maximum Likelihood Estimates ◽  
Viral Population ◽  
True Parameter ◽  
Subtype B ◽  
Exponential Growth Model ◽  
Parameter Values

Abstract We describe a unified set of methods for the inference of demographic history using genealogies reconstructed from gene sequence data. We introduce the skyline plot, a graphical, nonparametric estimate of demographic history. We discuss both maximum-likelihood parameter estimation and demographic hypothesis testing. Simulations are carried out to investigate the statistical properties of maximum-likelihood estimates of demographic parameters. The simulations reveal that (i) the performance of exponential growth model estimates is determined by a simple function of the true parameter values and (ii) under some conditions, estimates from reconstructed trees perform as well as estimates from perfect trees. We apply our methods to HIV-1 sequence data and find strong evidence that subtypes A and B have different demographic histories. We also provide the first (albeit tentative) genetic evidence for a recent decrease in the growth rate of subtype B.

Population genetics, phylogeography, and systematics of the thornyhead rockfishes (Sebastolobus) along the deep continental slopes of the North Pacific Ocean

2000 ◽  
Vol 57 (8) ◽  
pp. 1701-1717 ◽  
Author(s):  
Carol A Stepien ◽  
Alison K Dillon ◽  
Amy K Patterson
Keyword(s):  
Pacific Ocean ◽  
Phylogenetic Trees ◽  
Sequence Data ◽  
North Pacific Ocean ◽  
Geographic Distance ◽  
The North ◽  
Continental Slopes ◽  
Genetic Patterns ◽  
Northern Pacific ◽  
Shortspine Thornyhead

Population genetic, phylogeographic, and systematic relationships are elucidated among the three species comprising the thornyhead rockfish genus Sebastolobus (Teleostei: Scorpaenidae). Genetic variation among sampling sites representing their extensive ranges along the deep continental slopes of the northern Pacific Ocean is compared using sequence data from the left domain of the mtDNA control region. Comparisons are made among the shortspine thornyhead (S. alascanus) (from seven locations), the longspine thornyhead (S. altivelis) (from five sites), which are sympatric in the northeast, and the broadbanded thornyhead (S. macrochir) (a single site) from the northwest. Phylogenetic trees rooted to Sebastes show that S. macrochir is the sister taxon of S. alascanus and S. altivelis. Intraspecific genetic variability is appreciable, with most individuals having unique haplotypes. Gene flow is substantial among some locations and others diverged significantly. Genetic divergences among sampling sites for S. alascanus indicate an isolation by geographic distance pattern. Genetic divergences for S. altivelis are unrelated to the hypothesis of isolation by geographic distance and appear to be more consistent with the hypothesis of larval retention in currents and gyres. Differences in geographic genetic patterns between the species are attributed to life history differences in their relative mobilities as juveniles and adults.

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