Weak large‐scale population genetic structure in a philopatric seabird,the European Shag Phalacrocorax aristotelis

Quantifying population genetic structure is fundamental to testing hypotheses regarding gene flow, population divergence and dynamics across large spatial scales. In species with highly mobile life‐history stages, where it is unclear whether such movements translate into effective dispersal among discrete philopatric breeding populations, this approach can be particularly effective. We used seven nuclear microsatellite loci and mitochondrial DNA (ND2) markers to quantify population genetic structure and variation across 20 populations (447 individuals) of one such species, the European Shag, spanning a large geographical range. Despite high breeding philopatry, rare cross‐sea movements and recognized subspecies, population genetic structure was weak across both microsatellites and mitochondrial markers. Furthermore, although isolation‐by‐distance was detected, microsatellite variation provided no evidence that open sea formed a complete barrier to effective dispersal. These data suggest that occasional long‐distance, cross‐sea movements translate into gene flow across a large spatial scale. Historical factors may also have shaped contemporary genetic structure: cluster analyses of microsatellite data identified three groups, comprising colonies at southern, mid‐ and northern latitudes, and similar structure was observed at mitochondrial loci. Only one private mitochondrial haplotype was found among subspecies, suggesting that this current taxonomic subdivision may not be mirrored by genetic isolation.     

Genetic drift drives evolution in the bird‐pollinated,terrestrial island endemic Grevillea georgeana (Proteaceae)

Plant species distributed across terrestrial islands can show significant genetic divergence among populations if seed and pollen dispersal are restricted. We assessed the genetic connectivity between populations of Grevillea georgeana, restricted to seven disjunct inselbergs in semi‐arid Western Australia. The phylogeographical pattern and population genetics of populations were determined using sequence data from two plastid DNA intergenic spacers and ten nuclear microsatellite loci. The plastid DNA markers indicated high genetic differentiation among the majority of populations. Haplotypes were restricted to individual inselbergs, with the exception of two that were shared among three isolated populations that formed part of an elongated greenstone belt and that may be connected via inaccessible populations of G. georgeana. There was also strong differentiation within some of the populations, suggesting long‐term isolation and persistence of G. georgeana on these terrestrial islands. Overall, the genetic patterns suggest limited seed dispersal, with differentiation in the plastid DNA genome being driven by genetic drift. In contrast, pollen movement, although generally restricted, may occur between neighbouring populations, resulting in a pattern of isolation by distance in the nuclear markers. This potential for limited or no seed dispersal, but connectivity via pollen flow, should be considered, given that many of the inselbergs are under consideration for resource development. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178 , 155–168.     

Population genetic structure in the Iberian cyprinid fish Iberochondrostoma lemmingii (Steindachner, 1866): disentangling species fragmentation and colonization processes

Interplay between the complex geography, hydrogeomorphological history, past climatic changes, and anthropogenic pressures is likely responsible for the current diversity and species' distribution of freshwater fishes in the Iberian Peninsula. To further disentangle the evolutionary processes promoting the diversification of endemic Iberian Cyprinids through time and space, we explored the patterns of genetic diversity of the Iberian arched‐mouth nase, Iberochondrostoma lemmingii (Steindachner, 1866), using molecular markers rendering at different timescales: the mitochondrial gene cytochrome b and seven microsatellite loci. Both markers showed significant differentiation of populations though the relative genetic distances among populations were different between markers. Mitochondrial DNA results indicate the isolation of hydrographic basins as the main driver of population differentiation, with Tejo as the centre of diversification. The results also support connections between Tejo, Guadiana, and Guadalquivir, with levels of divergence suggesting an earlier severance of Guadalquivir, whereas Guadiana and Tejo maintained connections until a more recent past. Establishment of more peripherial populations in small southern basins (Quarteira and Almargem) could have been ruled by founder events. However, the analysis of present‐day genetic configuration suggested by microsatellite data implies, for the first time, the involvement of other factors in the evolution of arched‐mouth Iberian nase populations. Relative low genetic distances between inter‐basin populations (Tejo and Guadiana) and the lack of concordance between differentiation and geography suggest a possible influence of human‐mediated translocations in the population genetic patterns of I. lemmingii. High intra‐basin differentiation levels were found within Tejo and Guadiana and may be associated with factors intrinsic to the species (e.g. low dispersal capability) or natural and/or artificial barriers to gene flow. The low vagility of the species appears to be an important factor influencing the evolutionary processes shaping the phylogeographical patterns of I. lemmingii, which could be relevant for the conservation of this threatened species. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 559–572.     

Phylogeography of the smooth snake Coronella austriaca (Serpentes: Colubridae): evidence for a reduced gene pool and a genetic discontinuity in Central Europe

The present study considers the genetic structure and phylogeography of the smooth snake (Coronella austriaca) in Central Europe, as analyzed on the basis of 14 microsatellite markers and a 284‐bp fragment of cytochrome b. We found deep divergence between western and south‐eastern Poland, suggesting at least two different colonization routes for Central Europe, originating in at least two different refugia. The west/south‐east divide was reflected in the haplotype distribution and topology of phylogenetic trees as defined by mitochondrial DNA, and in population structuring seen in the admixture analysis of microsatellite data. The well supported western European clade suggests that another refugium might have existed. We also note the isolation‐by‐distance and moderate‐to‐pronounced structuring in the examined geographical demes. Our data fit the assumption of the recently suggested sex‐biased dispersal, in that we found a strong divide in the maternal line, as well as evidence for a small but existent gene flow based on biparentally inherited microsatellite markers. All studied populations were very similar in respect of allelic richness, observed and expected heterozygosities, and inbreeding coefficients. However, some genetic characteristics were different from those expected compared to a similar fine‐scale study of C. austriaca from Great Britain. In the present study, we observed heterozygosity deficit, high inbreeding, and low Garza–Williamson indices, suggesting a reduction in population size. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115 , 195–210.     

Fine‐scale patterns of genetic divergence within and between morphologically variable subspecies of the sea urchin Heliocidaris erythrogramma (Echinometridae)

The spatial scale over which genetic divergences occur between populations and the extent that they are paralleled by morphological differences can vary greatly among marine species. In the present study, we use a hierarchical spatial design to investigate genetic structure in Heliocidaris erythrogramma occurring on near shore limestone reefs in Western Australia. These reefs are inhabited by two distinct subspecies: the thick‐spined Heliocidaris erythrogramma armigera and the thin‐spined Heliocidaris erythrogramma erythrogramma, each of which also have distinct colour patterns. In addition to pronounced morphological variation, H. erythrogramma exhibits a relatively short (3–4 days) planktonic phase before settlement and metamorphosis, which limits their capacity for dispersal. We used microsatellite markers to determine whether patterns of genetic structure were influenced more by morphological or life history limitations to dispersal. Both individual and population‐level analyses found significant genetic differentiation between subspecies, which was independent of geographical distance. Genetic diversity was considerably lower within H. e. erythrogramma than within H. e. armigera and genetic divergence was four‐fold greater between subspecies than among populations within subspecies. This pattern was consistent even at fine spatial scales (< 5 km). We did detect some evidence of gene flow between the subspecies; however, it appears to be highly restricted. Within subspecies, genetic structure was more clearly driven by dispersal capacity, although weak patterns of isolation‐by‐distance suggest that there may be other factors limiting gene exchange between populations. Our results show that spatial patterns of genetic structure in Western Australian H. erythrogramma is influenced by a range of factors but is primarily correlated with the distribution of morphologically distinct subspecies. This suggests the presence of reproductive barriers to gene exchange between them and demonstrates that morphological variation can be a good predictor of genetic divergence. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 578–592.     

Population structure of the mosquito Aedes aegypti (Stegomyia aegypti) in Pakistan

Eleven microsatellite markers were used to determine the genetic population structure and spread of Aedes aegypti (Stegomyia aegypti) (Diptera: Culicidae) in Pakistan using mosquitoes collected from 13 different cities. There is a single genetic cluster of Ae. aegypti in Pakistan with a pattern of isolation by distance within the population. The low level of isolation by distance suggests the long‐range passive dispersal of this mosquito, which may be facilitated by the tyre trade in Pakistan. A decrease in genetic diversity from south to north suggests a recent spread of this mosquito from Karachi. A strong negative correlation between genetic distance and the quality of road connections shows that populations in cities connected by better road networks are less differentiated, which suggests the human‐aided passive dispersal of Ae. aegypti in Pakistan. Dispersal on a large spatial scale may facilitate the strategy of introducing transgenic Ae. aegypti or intracellular bacteria such as Wolbachia to control the spread of dengue disease in Pakistan, but it also emphasizes the need for simple measures to control container breeding sites.     

Dispersal constraints and fine‐scale spatial genetic structure in two earthworm species

The limited dispersal ability of earthworms is expected to result in marked genetic isolation by distance and remarkable spatial patterns of genetic variation. To test this hypothesis, we investigated, using microsatellite loci, the spatial genetic structure of two earthworm species, Allolobophora chlorotica and Aporrectodea icterica, in two plots of less than 1 ha where a total of 282 individuals were collected. We used spatial autocorrelation statistics, partial Mantel tests of isolation‐by‐distance (IBD) and isolation‐by‐resistance (IBR), and Bayesian test of clustering to explore recent patterns involved in the observed genetic structure. For A. icterica, a low signal of genetic structure was detected, which may be explained by an important dispersal capacity and/or by the low polymorphism of the microsatellite loci. For A. chlorotica, a weak, but significant, pattern of IBD associated with positive autocorrelation was observed in one of the plots. In the other plot, which had been recently ploughed, two genetically differentiated clusters were identified. These results suggest a spatial neighbourhood structure in A. chlorotica, with neighbour individuals that tend to be more genetically similar to one another, and also highlight that habitat perturbation as a result of human activities may deeply alter the genetic structure of earthworm species, even at a very small scale. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 335–347.     

Gene dispersal inference across forest patches in an endangered medicinal tree: comparison of model‐based approaches

Propagule dispersal in plants is a fundamental mechanism for colonizing new sites and adapting to changing climates, as well as for maintaining genetic diversity. Contrasting past and current gene dispersal can provide useful insights to gauge the extent of recent human disturbances and guide management strategies. However, research on gene dispersal of plants is not yet exhaustive because evolutionary or environmental impacts are often species‐specific and most existing studies have focused on analysis of dispersal at a single site, which may not be helpful for landscape‐level inferences and management interventions. In the present study, we assessed whether current gene or propagule dispersal would be more restricted than past gene dispersal at multiple patches of the endangered medicinal tree, Prunus africana. We employed eight highly polymorphic microsatellite markers in conjunction with isolation‐by‐distance, spatial genetic structure (SGS), and parentage assignment models to estimate gene dispersal distance in a spatial extent of approximately 400 km². There was no significant difference between gene dispersal distances across the different models (Friedman chi‐squared = 7.286, d.f. = 5, P = 0.2002). Estimates of current gene dispersal distance were comparable to dispersal in the last few generations. However, gene dispersal distance was much shorter in smaller than bigger forest patches. Further, significant (P < 0.05) SGS was detected in most forest patches, with the extent of SGS among adults being stronger in the smaller than bigger patches. These results suggest the need for practicing enrichment plantings in most forest patches, particularly in the smaller ones, to assist gene exchange among individuals and patches. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 887–904.     

The interplay of dispersal limitation,rivers, and historical events shapes the genetic structure of an Amazonian frog

Disentangling the impact of landscape features such as rivers and historical events on dispersal is a challenging but necessary task to gain a comprehensive picture of the evolution of diverse biota such as that found in Amazonia. Adenomera andreae, a small, territorial, terrestrial frog species of the Amazonian forest represents a good model for such studies. We combined cytochrome b sequences with 12 microsatellites to investigate the genetic structure at two contrasted spatial scales in French Guiana: along a ～6‐km transect, to evaluate dispersal ability, and between paired bank populations along a ～65‐km stretch of the Approuague river, to test the effect of rivers as barriers to dispersal. We observed significant spatial genetic structure between individuals at a remarkably small geographical scale, and conclude that the species has a restricted dispersal ability that is probably tied to its life‐history traits. Mitochondrial and microsatellite data also indicate a high level of differentiation among populations on opposite banks of the river, and, in some cases, among populations on the same riverbank. These results suggest that the observed population structure in A. andreae is the result of restricted dispersal abilities combined with the action of rivers and Quaternary population isolation. Given that Amazonia hosts a great portion of anurans, as well as other small vertebrates, that display life‐history traits comparable with A. andreae, we argue that our analyses provide new insights into the complex interactions among evolutionary processes shaping Amazonian biodiversity. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 356–373.     

Contrasting patterns of genetic differentiation in Macaronesian lineages of Ilex (Aquifoliaceae)

Islands offer an interesting framework in which to study the effect of geographical isolation on population genetic differentiation. For plant species with high dispersal abilities, however, oceanic barriers may not represent a factor promoting strong population structure. In this work, we analysed seven nuclear microsatellite loci in Ilex (Aquifoliaceae), a bird‐dispersed plant group, to infer patterns of genetic differentiation among Macaronesian taxa: I. canariensis, I. perado ssp. lopezlilloi, I. perado ssp. platyphylla (Canary Islands) and I. perado ssp. azorica (Azores). In agreement with current taxonomic classification, our results revealed a high genetic differentiation between Ilex lineages (I. canariensis and the I. perado complex), and also supported previous hypotheses that these are the result of independent dispersal events to the islands. In contrast, genetic differentiation between I. perado ssp. azorica and the two subspecies from the Canaries was high, suggesting that taxonomic revision may be necessary. Levels of genetic variation at microsatellite loci in ssp. azorica were, in addition, the lowest reported among Macaronesian bird‐dispersed taxa. Lastly, low genetic differentiation was observed between subspecies occurring on the same island (sspp. platyphylla and lopezlilloi). In summary, our results revealed contrasting patterns between Macaronesian Ilex lineages: I. canariensis displayed moderate population structure across islands, whereas the I. perado complex showed strong differentiation among populations sampled on different islands. Thus, the Macaronesian Ilex taxa show that long‐distance dispersal syndromes (ornithochory) do not always ensure genetic connectivity across large areas in island systems. Plant groups that successfully colonized the islands on multiple occasions may have found barriers to gene flow within certain lineages. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 258–268.     

Divergence and molecular variation in common whelk Buccinum undatum (Gastropoda: Buccinidae) in Iceland: a trans‐Atlantic comparison

The dispersal and history of species affects their genetic population structure at both small and large geographical scales. The common whelk, Buccinum undatum, is a widespread subtidal gastropod in the North Atlantic that has no planktonic larvae and has thus limited dispersal capacity. The snail, which has been harvested by humans for centuries, is highly variable in morphology. To evaluate the population structure in the rich fishing grounds in western Iceland and its divergence from samples across the Atlantic, genetic patterns based on sequence variation in two mitochondrial (mt)DNA genes (COI and 16S) and five microsatellites were studied and compared with variation in populations from both sides of the Atlantic. Significant differences in allele and haplotype frequencies were found among samples separated by short distances along the coast of Iceland. Partition of the variation showed larger variance among samples obtained from distant regions than from neighbouring sites and genetic distances were correlated with geographical distance among populations in Europe. Phylogeographic patterns in mtDNA reveal different monophyletic lineages on both sides of the Atlantic, which predate the onset of the Ice Age and which may constitute cryptic species. Similar micro‐ and macrogeographical patterns were observed for the mtDNA and microsatellite markers, despite high frequencies of null alleles. Bayesian skyline reconstructions of the demographic history and mismatch distributions suggest that, although sizes of some populations were unaffected by Ice Age glaciations, others show signs of expansion after the Last Glacial Maximum. These phylogeographical patterns are consistent with patterns expected for low dispersal species that have survived in allopatric glacial refugial populations on both sides of the Atlantic and in deep‐sea refugia within each continent. The observed genetic structure has implications for conservation and sustainable management of the harvested populations. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 145–159.     

Phylogeography of the Japanese pipistrelle bat,Pipistrellus abramus,in China: the impact of ancient and recent events on population genetic structure

The influence of Pleistocene climatic oscillations on shaping the genetic structure of Asian biota is poorly known. The Japanese pipistrelle bat occurs over a wide range in eastern Asia, from Siberia to Japan. To test the relative impact of ancient and more recent events on genetic structure in this species, we combined mitochondrial (cytochrome b) and microsatellite markers to reconstruct its phylogeographic and demographic history on continental China and its offshore islands, Hainan Island and the Zhoushan Archipelago. Our mitochondrial DNA tree recovered two divergent geographical clades, indicating multiple glacial refugia in the region. The first clade was mainly confined to Hainan Island, indicating that gene flow between this population and the continent has been restricted, despite being repeatedly connected to the mainland during repeated glacial episodes. By contrast, haplotypes sampled on the Zhoushan Archipelago were mixed with those from the mainland, suggesting a recent shared history of expansion. Although microsatellite allele frequencies showed clear discontinuities across the sampling range, supporting the current isolation of both Hainan Island and the Zhoushan Archipelago, we also found clear evidence of more recent back colonization, probably via post‐glacial expansion or, in the latter case, occasional long distance dispersal. The results obtained highlight the importance of using multiple sets of markers for teasing apart the roles of ancient and more recent events on population genetic structure. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 582–594.     

Does long‐distance pollen dispersal preclude inbreeding in tropical trees? Fragmentation genetics of Dysoxylum malabaricum in an agro‐forest landscape

Tropical trees often display long‐distance pollen dispersal, even in highly fragmented landscapes. Understanding how patterns of spatial isolation influence pollen dispersal and interact with background patterns of fine‐scale spatial genetic structure (FSGS) is critical for evaluating the genetic consequences of habitat fragmentation. In the endangered tropical timber tree Dysoxylum malabaricum (Meliaceae), we apply eleven microsatellite markers with paternity and parentage analysis to directly estimate historic gene flow and contemporary pollen dispersal across a large area (216 km²) in a highly fragmented agro‐forest landscape. A comparison of genetic diversity and genetic structure in adult and juvenile life stages indicates an increase in differentiation and FSGS over time. Paternity analysis and parentage analysis demonstrate high genetic connectivity across the landscape by pollen dispersal. A comparison between mother trees in forest patches with low and high densities of adult trees shows that the frequency of short‐distance mating increases, as does average kinship among mates in low‐density stands. This indicates that there are potentially negative genetic consequences of low population density associated with forest fragmentation. Single isolated trees, in contrast, frequently receive heterogeneous pollen from distances exceeding 5 km. We discuss the processes leading to the observed patterns of pollen dispersal and the implications of this for conservation management of D. malabaricum and tropical trees more generally.     

Anthropogenic fragmentation may not alter pre‐existing patterns of genetic diversity and differentiation in perennial shrubs

Many plant species have pollination and seed dispersal systems and evolutionary histories that have produced strong genetic structuring. These genetic patterns may be consistent with expectations following recent anthropogenic fragmentation, making it difficult to detect fragmentation effects if no prefragmentation genetic data are available. We used microsatellite markers to investigate whether severe habitat fragmentation may have affected the structure and diversity of populations of the endangered Australian bird‐pollinated shrub Grevillea caleyi R.Br., by comparing current patterns of genetic structure and diversity with those of the closely related G. longifolia R.Br. that has a similar life history but has not experienced anthropogenic fragmentation. Grevillea caleyi and G. longifolia showed similar and substantial population subdivision at all spatial levels (global F′_ST = 0.615 and 0.454; S_p = 0.039 and 0.066), marked isolation by distance and large heterozygous deficiencies. These characteristics suggest long‐term effects of inbreeding in self‐compatible species that have poor seed dispersal, limited connectivity via pollen flow and undergo population bottlenecks because of periodic fires. Highly structured allele size distributions, most notably in G. caleyi, imply historical processes of drift and mutation were important in isolated subpopulations. Genetic diversity did not vary with population size but was lower in more isolated populations for both species. Through this comparison, we reject the hypothesis that anthropogenic fragmentation has impacted substantially on the genetic composition or structure of G. caleyi populations. Our results suggest that highly self‐compatible species with limited dispersal may be relatively resilient to the genetic changes predicted to follow habitat fragmentation.     

Levels and patterns of population genetic diversity in the red seaweed Chondrus crispus (Florideophyceae): a direct comparison of single nucleotide polymorphisms and microsatellites

Single nucleotide polymorphisms (SNPs) are predicted to supersede microsatellites as the marker of choice for population genetic studies in the near future. To date, however, very few studies have directly compared both marker systems in natural populations, particularly in non‐model organisms. In the present study, we compared the utility of SNPs and microsatellites for population genetic analysis of the red seaweed Chondrus crispus (Florideophyceae). Six SNP loci yielded very different patterns of intrapopulation genetic diversity compared to those obtained using seven moderately (mean 5.2 alleles) polymorphic microsatellite loci, although Bayesian clustering analysis gave largely congruent results between the two marker classes. A weak but significant pattern of isolation‐by‐distance was observed across scales from a few hundred metres to approximately 200 km using the combined SNP and microsatellite data set of 13 loci. Over larger scales, however, there was little correlation between genetic divergence and geographical distance. Our findings suggest that even a moderate number of SNPs is sufficient to determine patterns of genetic diversity across natural populations, and also highlight the fact that patterns of genetic variation in seaweeds arise through a complex interplay of short‐ and long‐term natural processes, as well as anthropogenic influence. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 108 , 251–262.     

Testing the ‘Pleistocene species pump’ in alpine habitats: lineage diversification of flightless ground beetles (Coleoptera: Carabidae: Nebria) in relation to altitudinal zonation

Alpine species often have similar demographic responses to Pleistocene climate changes, but exhibit different spatial patterns of genetic diversity. Using a comparative phylogeographical approach, we examined the factors influencing lineage formation in three alpine carabid beetles of the genus Nebria Latreille inhabiting the California Sierra Nevada. These flightless beetles differ in altitudinal zonation and habitat preferences, but overlap spatially, have limited dispersal capacities and share life history characteristics. Species distribution modelling predicted decreasing population connectivity in relation to increasing altitudinal preferences. Diversity patterns at the cytochrome oxidase subunit I gene revealed north–south genetic structure and recent population growth in all three species. The high‐elevation‐restricted species, Nebria ingens Horn, exhibited a deep phylogeographical split, morphological divergence and evidence of limited, unidirectional gene flow towards the south. This was supported by additional data from three nuclear genes and isolation with migration analysis. Nebria spatulata Van Dyke, inhabiting an intermediate altitudinal range, exhibited fixed morphological differences between northern and southern populations, but showed limited structure. The broadly distributed Nebria ovipennis LeConte showed less structure and lacked morphological variation. Diversification of these Nebria species supports the role of altitudinal zonation in lineage formation and is consistent with the Pleistocene species pump model. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

Multiple cryptic genetic units in Hypothenemus hampei (Coleoptera: Scolytinae): evidence from microsatellite and mitochondrial DNA sequence data

Hypothenemus hampei is the most important insect pest of coffee and has spread to most coffee‐growing countries worldwide. There have been very few studies and none have addressed the population genetics of the beetle using microsatellite markers. In the present study, 683 individuals collected from 37 locations in 18 countries worldwide were screened at nine polymorphic microsatellite loci. Sixty‐five out the 683 and six additional individuals were analyzed on a 400‐bp fragment of the mitochondrial cytochrome oxidase I gene. Bayesian clustering analysis and phylogenetic approaches were used to infer the genetic structure of H. hampei over the sampling that encompassed almost all its range. Microsatellite markers made it possible to achieve sufficiently significant power for the delineation of five morphocryptic evolutionary units. Supported by 27 new COI haplotypes, an unexpected considerably high level of genetic differentiation and genetic divergence was revealed between five geographically delineated clusters. Both markers and approaches showed that the clusters included specimens from (1) Ethiopia, (2) Kenya and Uganda, (3) Brazil, (4) Central America excluding Jamaica, and (5) all samples from Asia, West Africa, and Jamaica. These findings clearly suggest the existence of a ‘species complex in H. hampei’. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 113–129.     

Extensive local‐scale gene flow and long‐term population stability in the intertidal mollusc Katharina tunicata (Mollusca: Polyplacophora)

The dispersal capabilities of intertidal organisms may represent a key factor to their survival in the face of global warming, as species that cannot adapt to the various effects of climate change will have to migrate to track suitable habitat. Although species with pelagic larval phases might be expected to have a greater capacity for dispersal than those with benthic larvae, interspecies comparisons have shown that this is not always the case. Consequently, population genetic approaches are being increasingly used to gain insights into dispersal through studying patterns of gene flow. In the present study, we used nuclear single‐nucleotide polymorphisms (SNPs) and mitochondrial DNA (mtDNA) sequencing to elucidate fine‐scale patterns of genetic variation between populations of the Black Katy Chiton, Katharina tunicata, separated by 15–150 km in south‐west Vancouver Island. Both the nuclear and mitochondrial data sets revealed no genetic differentiation between the populations studied, and an isolation‐with‐migration analysis indicated extensive local‐scale gene flow, suggesting an absence of barriers to dispersal. Population demographic analysis also revealed long‐term population stability through previous periods of climate change associated with the Pleistocene glaciations. Together, the findings of the present study suggest that this high potential for dispersal may allow K. tunicata to respond to current global warming by tracking suitable habitat, consistent with its long‐term demographic stability through previous changes in the Earth's climate. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 589–597.     

Isolation and characterization of trinucleotide microsatellites in African malaria mosquito Anopheles funestus

We developed microsatellite markers for an important African malaria mosquito Anopheles funestus Giles. The microsatellite‐enriched genomic library was constructed and screened with single‐strand oligonucleotides [(CCT)₁₇, (AAT)₁₇, (CAG)₁₇ and (GA)₂₅] as probes. Among the 47 pairs of polymerase chain reaction primers screened, 31 produced successful and consistent amplification. Although only a few A. funestus individuals from one geographical location were used to screen microsatellite marker polymorphism, 27 markers were found polymorphic and four markers monomorphic. Most polymorphic markers are trinucleotide markers. Isolation of polymorphic microsatellite markers provide useful tools for A. funestus population genetic studies and genome mapping.     

Is life history a barrier to dispersal? Contrasting patterns of genetic differentiation along an oceanographically complex coast

Extreme variation in early life‐history strategies is considered a moderately good predictor of genetic subdivision and hence dispersal for a range of marine species. In reality, however, a good deal of population differentiation must reflect historical effects, more subtle variation in life histories, and, particularly, the interaction of larvae with oceanographic processes. Using a combination of allozyme and microsatellite markers, we show that the large‐scale genetic structure of populations of three species (direct and planktonically developing cushion stars and a planktonic developing sea anemone that is also asexually viviparous) varies consistently, in line with the predicted capacity for dispersal within three geographic regions. We detected high levels of genetic subdivision for the direct developing cushion star (F_ST = 0.6), low levels for the planktonically developing cushion star (F_ST = 0.009), and intermediate levels for the sexual/asexual sea anmone (F_ST = 0.19). These patterns are exhibited despite the highly variable patterns of current movement and the presence of biogeographic barriers. Our results suggest that, although there is large scale genetic differentiation for two species, patterns of population connectivity are remarkably consistent within major regions and do not reflect variation in major oceanographic processes or genetic discontinuity coincident with biogeographic boundaries. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 106–116.