Mitochondrial and Nuclear DNA Based Genetic Assessment Indicated Distinct Variation and Low Genetic Exchange Among the Three Subspecies of Swamp Deer (<Emphasis Type="Italic">Rucervus</Emphasis> <Emphasis Type="Italic">duvaucelii</Emphasis>)

The swamp deer (Rucervus duvaucelii) occurs, primarily, in the wet grasslands of the Himalayan foothills as well as the dry grasslands of central India. Three subspecies have been identified, namely R. duvaucelii duvaucelii, R. duvaucelii branderi and R. duvaucelii ranjitsinhi. Degradation of grassland habitats led to a drastic decline in the total swamp deer population in the early 19th century. Even though the species has recently shown signs of recovery, it is still vulnerable to the small-population paradigm. Effective management plans need to be put in place to increase the population through scientific intervention. The current genetic variation within the three subspecies of R. duvaucelii is unclear, and this is hindering effective conservation planning. We examined the genetic variability, population structure and demography of the three subspecies of swamp deer using the mtDNA control region and microsatellite analysis. Despite the spatial isolation of the populations, we found a high level of variation and weak divergence among the subspecies. The genetic differentiation (F _ST ) between the subspecies and the mismatch distribution of haplotypes indicated recent colonization by these subspecies. Population bottleneck analysis indicated that the existing subspecies and their populations are at demographic equilibrium and are stable. The study highlights the need for effective conservation management intervention to maintain the population size and genetic diversity. It also indicates that all the subspecies need to be managed as separate conservation units.     

Genetic Analysis of the <Emphasis Type="Italic">Indri</Emphasis> Reveals No Evidence of Distinct Subspecies

Subspecies were traditionally defined by identifying gaps between phenotypes across the geographic range of a species, and may represent important units in the development of conservation strategies focused on preserving genetic diversity. Previous taxonomic research proposed that phenotypic variation between scattered Indri indri populations warranted the naming of two distinct subspecies, I. i. indri and I. i. variegatus. We tested these subspecific designations using mitochondrial sequence data generated from the control region or D-loop (569 bp) and a large section (2362 bp) of multiple genes and tRNAs known as Pastorini’s fragment and nuclear microsatellite markers. This study used 114 samples of I. indri from 12 rainforest sites in eastern Madagascar, encompassing the entire range of the species. These genetic samples represent multiple populations from low- and high-elevation forests from both putative subspecies. Molecular analyses of the mitochondrial sequence data did not support the two proposed subspecies. Furthermore, the microsatellite analyses showed no significant differences across the range beyond population level differentiation. This study demonstrates the utility of incorporating multiple lines of evidence in addition to phenotypic traits to define species or subspecies.     

Genetic distinctiveness of brown pelicans (<Emphasis Type="Italic">Pelecanus occidentalis</Emphasis>) from the Galápagos Islands compared to continental North America

We examined population differentiation across a substantial portion of the range of the brown pelican (Pelecanus occidentalis) to assess (1) the genetic distinctness of the Galápagos subspecies (P. o. urinator) and (2) genetic differentiation between subspecies that inhabit the coasts of North and Central America (P. o. californicus and P. o. carolinensis). Birds were sampled from coastal California, coastal Florida, and the Galápagos Islands. Using a 957 bp (bp) fragment of the NADH dehydrogenase subunit 2 (ND2) gene, 661 bp of the mitochondrial control region, and eleven microsatellite loci we characterize population genetic differentiation among 158 brown pelicans. The Galápagos subspecies is genetically distinct from the sampled continental subspecies, possessing a unique ND2 haplotype and unique mitochondrial control region haplotypes. Samples from the two continental subspecies all possessed the same ND2 haplotype and shared four mitochondrial control region haplotypes. Bayesian clustering in STRUCTURE placed the Galápagos subspecies in a distinct genetic group with high probability, but could not differentiate the continental subspecies from one another. Estimates of migration rates from BayesAss indicated substantial migration between continental subspecies, but no migration between the Galápagos subspecies and either continental subspecies. There are clearly two Evolutionarily Significant Units within the range of the brown pelican, which warrants conservation attention. Further investigation should determine how the un-sampled subspecies (P. o. murphyi and P. o. occidentalis) fit into the broader picture.     

From species to individuals: combining barcoding and microsatellite analyses from non-invasive samples in plant ecology studies

By means of DNA barcoding and microsatellite analyses, we studied the species and individuals of legitimate seed dispersers of the Mediterranean shrub Pistacia lentiscus, a keystone species that represents the main source of food in winter for frugivorous birds. We collected dropping of birds containing seeds, and after DNA extraction we amplified and sequenced a fragment of the mitochondrial COI gene. Through BLASTN queries of the sequenced fragments against registered sequences in the GenBank database we identified the bird species that are currently dispersing P. lentiscus seeds. Further, through the amplification of specific nuclear microsatellite loci we calculated standard genetic diversity parameters of the population of birds from the genus Sylvia (the blackcap and Sardinian warbler), the most important dispersers of P. lentiscus. Five bird species were identified as seed dispersers through their barcode match. Further, we found that S. melanocephala displayed slightly lower levels of genetic diversity than S. atricapilla. In this study we show how the genetic analyses of environmental faecal samples can be a useful and convenient tool for the study of plant-frugivore interactions through the ascertainment of the identity of the species involved and through the analyses of genetic variability of their populations.     

The role of ecological factors in determining phylogeographic and population genetic structure of two sympatric island skinks (<Emphasis Type="Italic">Plestiodon kishinouyei</Emphasis> and <Emphasis Type="Italic">P. stimpsonii</Emphasis>)

We conducted comparative phylogeographic and population genetic analyses of Plestiodon kishinouyei and P. stimpsonii, two sympatric skinks endemic to islands in the southern Ryukyus, to explore different factors that have influenced population structure. Previous phylogenetic studies using partial mitochondrial DNA indicate similar divergence times from their respective closest relatives, suggesting that differences in population structure are driven by intrinsic attributes of either species rather than the common set of extrinsic factors that both presumably have been exposed to throughout their history. In this study, analysis of mtDNA sequences and microsatellite polymorphism demonstrate contrasting patterns of phylogeography and population structure: P. kishinouyei exhibits a lower genetic variability and lower genetic differentiation among islands than P. stimpsonii, consistent with recent population expansion. However, historical demographic analyses indicate that the relatively high genetic uniformity in P. kishinouyei is not attributable to recent expansion. We detected significant isolation-by-distance patterns among P. kishinouyei populations on the land bridge islands, but not among P. stimpsonii populations occurring on those same islands. Our results suggest that P. kishinouyei populations have maintained gene flows across islands until recently, probably via ephemeral Quaternary land bridges. The lower genetic variability in P. kishinouyei may also indicate smaller effective population sizes on average than that of P. stimpsonii. We interpret these differences as a consequence of ecological divergence between the two species, primarily in trophic level and habitat preference.     

De novo development and characterization of polymorphic microsatellite markers in a schilbid catfish, <Emphasis Type="Italic">Silonia silondia</Emphasis> (Hamilton, 1822) and their validation for population genetic studies

The stock characterization of wild populations of Silonia silondia is important for its scientific management. At present, the information on genetic parameters of S. silondia is very limited. The species-specific microsatellite markers were developed in current study. The validated markers were used to genotype individuals from four distant rivers. To develop de novo microsatellite loci, an enriched genomic library was constructed for S. silondia using affinity–capture approach. The markers were validated for utility in population genetics. A total number of 76 individuals from four natural riverine populations were used to generate data for population analysis. The screening of isolated repeat sequences yielded eleven novel polymorphic microsatellite loci. The microsatellite loci exhibited high level of polymorphism, with 6–24 alleles per locus and the PIC value ranged from 0.604 to 0.927. The observed (Ho) and expected (He) heterozygosities ranged from 0.081 to 0.84 and 0.66 to 0.938, respectively. The AMOVA analysis indicated significant genetic differentiation among riverine populations (overall F_ST = 0.075; P < 0.0001) with maximum variation (92.5 %) within populations. Cross-priming assessment revealed successful amplification (35–38 %) of heterologous loci in four related species viz. Clupisoma garua, C. taakree, Ailia coila and Eutropiichthys vacha. The results demonstrated that these de novo polymorphic microsatellite loci are promising for population genetic variation and diversity studies in S. silondia. Cross-priming results indicated that these primers can help to get polymorphic microsatellite loci in the related catfish species of family Schilbidae.     

Molecular genetic analysis of five extant reserves of black honeybee <Emphasis Type="Italic">Apis melifera melifera</Emphasis> in the Urals and the Volga region

Local populations of the black honeybee Apis mellifera mellifera from the Urals and the Volga region were examined in comparison with local populations of southern honeybee subspecies A. m. caucasica and A. m. carpatica from the Caucasus and the Carpathians. Genetic analysis was performed on the basis of the polymorphism of nine microsatellite loci of nuclear DNA and the mtDNA COI–COII locus. On the territory of the Urals and the Volga region, five extant populations (reserves) of the black honeybee A. m. mellifera were identified, including the Burzyanskaya, Tatyshlinskaya, Yuzhno-Prikamskaya, Visherskaya, and Kambarskaya populations. These five populations are the basis of the modern gene pool of the black honeybee A. m. mellifera from the Urals and the Volga region. The greatest proportion of the remaining indigenous gene pool of A. m. mellifera (the core of the gene pool of the population of A. m. mellifera) is distributed over the entire territory of Perm krai and the north of the Republic of Bashkortostan. For the population of A. m. mellifera from the Urals and the Volga region, the genetic standards were calculated, which will be useful for future population studies of honeybees.     

Development and characterization of twelve microsatellite markers for <Emphasis Type="Italic">Porphyra linearis</Emphasis> Greville

The genus Porphyra (and its sister genus Pyropia) contains important red algal species that are cultivated and/or harvested for human consumption, sustaining a billion-dollar aquaculture industry. A vast amount of research has been focused on species of this genus, including studies on genetics and genomics among other areas. Twelve novel microsatellite markers were developed here for Porphyra linearis. Markers were characterized using 32 individuals collected from four natural populations of P. linearis with total heterozygosity varying from 0.098 to 0.916. The number of alleles per locus ranged from 2 to 18. All markers showed cross amplification with Porphyra umbilicalis and/or Porphyra dioica. These polymorphic microsatellite markers are useful for investigating population genetic diversity and differentiation in P. linearis and may become useful for other genetic research on the reproductive biology of this important species.     

Historical range contraction,and not taxonomy,explains the contemporary genetic structure of the Australian tree <Emphasis Type="Italic">Acacia dealbata</Emphasis> Link

Irrespective of its causes, strong population genetic structure indicates a lack of gene flow. Understanding the processes that underlie such structure, and the spatial patterns it causes, is valuable for conservation efforts such as restoration. On the other hand, when a species is invasive outside its native range, such information can aid management in the non-native range. Here we explored the genetic characteristics of the Australian tree Acacia dealbata in its native range. Two subspecies of A. dealbata have previously been described based on morphology and environmental requirements, but recent phylogeographic data raised questions regarding the validity of this taxonomic subdivision. The species has been widely planted within and outside its native Australian range and is also a highly successful invasive species in many parts of the world. We employed microsatellite markers to investigate the population genetic diversity and structure among 42 A. dealbata populations from across the species’ native range. We also tested whether environmental variables purportedly relevant for the putative separation of subspecies are linked with population genetic differentiation. We found no relationship between population genetic structure of A. dealbata in Australia and these environmental features. Rather, we identified two geographically distinct genetic clusters that corresponded with populations in the northeastern part of mainland Australia, and the southern mainland and Tasmanian range of the species. Our results do not support the taxonomic subdivision of the species into two distinct subspecies based on environmental features. We therefore assume that the observed morphological differences between the putative subspecies are plastic phenotypic responses. This study provides population genetic information that will be useful for the conservation of the species within Australia as well as to better understand the invasion dynamics of A. dealbata.     

A fifth major genetic group among honeybees revealed in Syria

Background

Apiculture has been practiced in North Africa and the Middle-East from antiquity. Several thousand years of selective breeding have left a mosaic of Apis mellifera subspecies in the Middle-East, many uniquely adapted and survived to local environmental conditions. In this study we explore the genetic diversity of A. mellifera from Syria (n?=?1258), Lebanon (n?=?169) and Iraq (n?=?35) based on 14 short tandem repeat (STR) loci in the context of reference populations from throughout the Old World (n?=?732).

Results

Our data suggest that the Syrian honeybee Apis mellifera syriaca occurs in both Syrian and Lebanese territories, with no significant genetic variability between respective populations from Syria and Lebanon. All studied populations clustered within a new fifth independent nuclear cluster, congruent with an mtDNA Z haplotype identified in a previous study. Syrian honeybee populations are not associated with Oriental lineage O, except for sporadic introgression into some populations close to the Turkish and Iraqi borders. Southern Syrian and Lebanese populations demonstrated high levels of genetic diversity compared to the northern populations.

Conclusion

This study revealed the effects of foreign queen importations on Syrian bee populations, especially for the region of Tartus, where extensive introgression of A. m. anatolica and/or A. m. caucasica alleles were identified. The policy of creating genetic conservation centers for the Syrian subspecies should take into consideration the influence of the oriental lineage O from the northern Syrian border and the large population of genetically divergent indigenous honeybees located in southern Syria.

     

Molecular genetic diversification of the lizard complex <Emphasis Type="Italic">Darevskia raddei</Emphasis> (Sauria: Lacertidae): Early stages of speciation

To characterize the molecular genetic diversity of the genus Darevskia, several populations were examined by the inter-SINE-PCR method, reporting the number and sizes of the spacers between individual copies of SINE-like interspersed repeats. Examination of 17 D. raddei geographical populations and several reference species revealed unequal genetic differences, measured as Nei and Li’s genetic distances (D_NL), for different groups of samples. The highest homogeneity was observed for the apparently panmictic D. raddei nairensis population from the basin of the Hrazdan River: genetic differences within each of the five samples and between them were similarly low (less than 0.1). The difference between ten samples of D. raddei raddei from Armenia and Karabakh (0.2–0.3) was somewhat higher than the interindividual difference within each sample (0.1–0.2), indicating that the samples belonged to different populations. The assumption was supported by the phylogenetic tree topology and multidimensional scaling. The differences between samples from the morphological subspecies D. raddei raddei and D. raddei nairensis ranged 0.3–0.4. The difference of two D. raddei raddei samples of Talysh (Azerbaijan) from other samples of the same subspecies corresponded to the subspecific level. The genetic distances between the good species D. raddei and D. rudis was 0.6–0.7. In terms of D_NL, a questionable population from northwestern Turkey (“D. tristis”) was closer to D. rudis (D_NL = 0.45), probably representing its subspecies. The phylogeography of D. raddei is discussed.     

Genetic diversity and genetic structure of the Siberian roe deer (<Emphasis Type="Italic">Capreolus pygargus</Emphasis>) populations from Asia

Background

The roe deer, Capreolus sp., is one of the most widespread meso-mammals of Palearctic distribution, and includes two species, the European roe deer, C. capreolus inhabiting mainly Europe, and the Siberian roe deer, C. pygargus, distributed throughout continental Asia. Although there are a number of genetic studies concerning European roe deer, the Siberian roe deer has been studied less, and none of these studies use microsatellite markers. Natural processes have led to genetic structuring in wild populations. To understand how these factors have affected genetic structure and connectivity of Siberian roe deer, we investigated variability at 12 microsatellite loci for Siberian roe deer from ten localities in Asia.

Results

Moderate levels of genetic diversity (H _E = 0.522 to 0.628) were found in all populations except in Jeju Island, South Korea, where the diversity was lowest?(H _E?= 0.386). Western populations showed relatively low genetic diversity and higher degrees of genetic differentiation compared with eastern populations (mean Ar = 3.54 (east), 2.81 (west), mean F _ST = 0.122). Bayesian-based clustering analysis revealed the existence of three genetically distinct groups (clusters) for Siberian roe deer, which comprise of the Southeastern group (Mainland Korea, Russian Far East, Trans-Baikal region and Northern part of Mongolia), Northwestern group (Western Siberia and Ural in Russia) and Jeju Island population. Genetic analyses including AMOVA (F _RT = 0.200), Barrier and PCA also supported genetic differentiation among regions separated primarily by major mountain ridges, suggesting that mountains played a role in the genetic differentiation of Siberian roe deer. On the other hand, genetic evidence also suggests an ongoing migration that may facilitate genetic admixture at the border areas between two groups.

Conclusions

Our results reveal an apparent pattern of genetic differentiation among populations inhabiting Asia, showing moderate levels of genetic diversity with an east-west gradient. The results suggest at least three distinct management units of roe deer in continental Asia, although genetic admixture is evident in some border areas. The insights obtained from this study shed light on management of Siberian roe deer in Asia and may be applied in conservation of local populations of Siberian roe deer.

     

Genetic diversity,effective population size,and structure among black bear populations in the Lower Mississippi Alluvial Valley,USA

Multiple small populations of American black bears Ursus americanus, including the recently delisted Louisiana black bear subspecies U. a. luteolus, occupy a fragmented landscape in the Lower Mississippi Alluvial Valley, USA (LMAV). Populations include bears native to the LMAV, bears translocated from Minnesota during the 1960s, and recently reintroduced and colonizing populations sourced from within the LMAV. We estimated population structure, gene flow, and genetic parameters important to conservation of small populations using genotypes at 23 microsatellite markers for 265 bears from seven populations. We inferred five genetic clusters corresponding to the following populations: White River and western Mississippi, Tensas River and Three Rivers, Upper Atchafalaya, Lower Atchafalaya, and Minnesota. Upper Atchafalaya was suggested as the product of Minnesota-sourced translocations, but those populations have since diverged, likely because of a founder effect followed by genetic drift and isolation. An admixture zone recently developed in northeastern Louisiana and western Mississippi between migrants from White River and Tensas River, resulting in a Wahlund effect. However, gene flow among most populations has been limited and considerable genetic differentiation accumulated (global F_ST?=?0.22), particularly among the three Louisiana black bear populations that existed when federal listing occurred. Consistent with previous bottlenecks, founder effects, and persisting isolation, all LMAV bear populations had low genetic diversity (A_R?=?2.08–4.81; H_E?=?0.36–0.63) or small effective population size (N_E?=?3–49). Translocating bears among populations as part of a regional genetic restoration program may help improve genetic diversity and increase effective population sizes.     

High-throughput sequencing of <Emphasis Type="Italic">Prunus ferganensis</Emphasis> indicates that it is a geographical population of <Emphasis Type="Italic">P. persica</Emphasis>

Peach belongs to the genus Prunus, which includes Prunus persica and its relative species, P. mira, P. davidiana, P. kansuensis, and P. ferganensis. Of these, P. ferganensis have been classified as a species, subspecies, or geographical population of P. persica. To explore the genetic difference between P. ferganensis and P. persica, high-throughput sequencing was used in different peach accessions belonging to different species. First, low-depth sequencing data of peach accessions belonging to four categories revealed that similarity between P. ferganensis and P. persica was similar to that between P. persica accessions from different geographical populations. Then, to further detect the genomic variation in P. ferganensis, the P. ferganensis accession “Xinjiang Pan Tao 1” and the P. persica accession “Xia Miao 1” were sequenced with high depth, and sequence reads were assembled. The results showed that the collinearity of “Xinjiang Pan Tao 1” with the reference genome “Lovell” was higher than that of “Xia Miao 1” and “Lovell” peach. Additionally, the number of genetic variants, including single nucleotide polymorphisms (SNPs), structural variations (SVs), and the specific genes annotated from unmapped sequence in “Xia Miao 1” was higher than that in “Xinjiang Pan Tao 1” peach. The data showed that there was a close distance between “Xinjiang Pan Tao 1” (P. ferganensis) and reference genome which belong to P. persica, comparing “Xia Miao 1” (P. persica) and reference ones. The results accompany with phylogenetic tree and structure analysis confirmed that P. ferganensis should be considered as a geographic population of P. persica rather than a subspecies or a distinct species. Furthermore, gene ontology analysis was performed using the gene comprising large-effect variation to understand the phenotypic difference between two accessions. The result revealed that the pathways of gene function affected by SVs but SNPs and insertion-deletions markedly differed between the two peach accessions.     

Genetic diversity of the house mouse <Emphasis Type="Italic">Mus musculus</Emphasis> and geographic distribution of its subspecies-specific RAPD markers on the territory of Russia

Genetic diversity and geographic distribution of taxon-specific RAPD markers was examined in ten local populations of the house mouse Mus musculus (n = 42). The house mice were generally characterized by moderate genetic variation: polymorphism P ₉₉ = 60%, P ₉₅ = 32.57%; heterozygosity H = 0.12; the observed allele number n _a = 1.6; the effective allele number n _e = 1.18; the within-population differentiation ?_s = 0.388; and Shannon index I = 0.19. The degree of genetic isolation of individual local populations was greatly variable. The genetic subdivision index G _st varied from 0.162 to 0.770 at the gene flow of Nm = 2.58?0.149, while the among-population distances D _N varied from 0.026 to 0.178. The largest part of the genetic diversity was found among the populations (H _T = 0.125), while the within-population diversity was twice lower (H _S = 0.06). The samples examined were well discriminated relative to the sets of RAPD markers. The character distribution pattern provided conditional subdivision of the mice into the “western” and the “eastern” groups with the putative boarder along the Baikal Lake. The first group was characterized by the prevalence of the markers typical of M. m. musculus and M. m. domesticus. The second group was characterized by the prevalence of the markers typical of M. m. musculus, M. m. gansuensis, M. m. castaneus, M. m. domesticus, and M. m. wagneri. The genotype of the nominative subspecies M. m. musculus was background for all populations. In the populations examined some of earlier described subspecies-specific molecular markers were found at different frequencies, pointing to the involvement of several subspecies of M. musculus in the process of hybridization.     

Natural hybridization among subspecies of <Emphasis Type="Italic">Turnera sidoides</Emphasis> L. (Passifloraceae) revealed by morphological and genetic evidence

Turnera sidoides is a complex of outcrossing, perennial, rhizomatous herbs that is widely distributed in southern South America. Five subspecies are recognized taxonomically based on morphological features and geographical distribution. In certain regions, the areas of distribution of the subspecies overlap partially. In such contact zones, the extent of reproductive barriers among subspecies is still largely unknown, but morphologically intermediate individuals have been found in the field, indicating that hybridization may actually occur between subspecies. Crossability among subspecies of T. sidoides has been shown by experimental studies with cultivated plants, but the mechanisms involved in natural populations are still unknown. To investigate the mechanisms that underlie gene flow within the T. sidoides complex, in this paper we analyze the morphological and genetic variation, as well as the crossability among taxa in a contact zone between subspecies pinnatifida and sidoides, in southeastern Uruguay. Our results constitute the first evidences of ongoing natural hybridization between subspecies of T. sidoides and suggest that, although hybridization may not have been of significance in the early phase of the species differentiation, reticulate evolution is ongoing enhancing the current morphological and genetic variability of the complex.     

Genetic structure of Sakhalin spruce (<Emphasis Type="Italic">Picea glehnii</Emphasis>) in northern Japan and adjacent regions revealed by nuclear microsatellites and mitochondrial gene sequences

The genetic structure of Sakhalin spruce (Picea glehnii) was studied across the natural range of the species, including two small isolated populations in south Sakhalin and Hayachine, by using six microsatellite loci and maternally inherited mitochondrial gene sequences. We also analyzed P. jezoensis, a sympatric spruce in the range. Genetic diversity of P. glehnii was higher in central Hokkaido and the lowest in the Hayachine. Bayesian clustering and principal coordinate analysis by using the microsatellites indicated that the Hayachine was clearly distinct from other populations, implying that it had undergone strong genetic drift since the last glacial period. P. glehnii harbored four mitochondrial haplotypes, two of which were shared with P. jezoensis. One of the two was observed without geographical concentration, suggesting its derivation from ancestral polymorphism. Another was observed in south Sakhalin and in P. jezoensis across Sakhalin. The Bayesian clustering—by using four microsatellite loci, including P. jezoensis populations—indicated unambiguous species delimitation, but with possible admixture of P. jezoensis genes into P. glehnii in south Sakhalin, where P. glehnii is abundantly overwhelmed by P. jezoensis; this might explain the occurrence of introgression of the haplotype of P. jezoensis into P. glehnii.     

Population genetic analysis of Euro-Arctic polar cod <Emphasis Type="Italic">Boreogadus saida</Emphasis> suggests fjord and oceanic structuring

Polar cod, Boreogadus saida, is a key species in Arctic marine ecosystems; however, its genetic population structure is largely undescribed. The population genetic structure of 472 B. saida specimens among nine locations in the north-east Atlantic was revealed using 12 microsatellite loci. Pairwise F _ST comparisons showed significant population differentiation between B. saida sampled inside fjords in Svalbard and north-east Greenland, as compared to B. saida from the shelf. The observed genetic variation was not a function of isolation by distance, and it is speculated that B. saida populations inhabiting fjords may have become reproductively isolated from shelf-dwelling B. saida during the last post-glacial recolonization.