Genetic diversity,genetic structure and phylogeography of the Iberian endemic Gypsophila struthium (Caryophyllaceae) as revealed by AFLP and plastid DNA sequences: connecting habitat fragmentation and diversification

Iberian gypsum outcrops are highly fragmented and ecologically challenging environments for plant colonization. As gypsophytes occur exclusively in such habitats, they are ideal models for the study of both the effects of habitat fragmentation and selection on population genetic diversity and structure. In this study, we used amplified fragment length polymorphism (AFLP) and plastid DNA sequences to investigate the phylogeographical history of the Iberian plant Gypsophila struthium (Caryophyllaceae), a widespread endemic restricted to Iberian gypsum outcrops. Gypsophila struthium consists of two subspecies that differ in the architecture of their inflorescence and have mostly allopatric ranges. Gypsophila struthium subsp. struthium occurs in central, eastern and south‐eastern Iberia, whereas G. struthium subsp. hispanica occurs in northern and eastern areas. AFLPs revealed low but significant genetic differentiation between the subspecies, probably as a result of a recent diversification during the Pliocene–Pleistocene. In the geographical contact zone between the taxa, the Bayesian analyses revealed populations with mixed ancestries and genetic clusters predominantly of one or the other subspecies, indicating incomplete reproductive barriers between them. Plastid DNA haplotypes revealed strong geographical structure and testified to processes of isolation by distance and continuous range expansion for some haplotype clades. The Bayesian analyses of the population structure of AFLP data and nested clade phylogeographical analysis (NCPA) of plastid haplotypes revealed that the putative ancestral range corresponded to central and eastern populations of G. struthium subsp. struthium, with those lineages contributing through more recent expansion to increased genetic diversity and structure of the south‐eastern and eastern ranges of this subspecies and to the diversification of G. struthium subsp. hispanica in northern and eastern gypsum outcrops. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 654–675.     

Mosaics in the mangroves: allopatric diversification of tree‐climbing mudwhelks (Gastropoda: Potamididae: Cerithidea) in the Indo‐West Pacific

The Indo‐Australian Archipelago (IAA) is the richest area of biodiversity in the marine realm, yet the processes that generate and maintain this diversity are poorly understood and have hardly been studied in the mangrove biotope. Cerithidea is a genus of marine and brackish‐water snails restricted to mangrove habitats in the Indo‐West Pacific, and its species are believed to have a short pelagic larval life. Using molecular and morphological techniques, we demonstrate the existence of 15 species, reconstruct their phylogeny and plot their geographical ranges. Sister species show a pattern of narrowly allopatric ranges across the IAA, with overlap only between clades that show evidence of ecological differentiation. These allopatric mosaic distributions suggest that speciation may have been driven by isolation during low sea‐level stands, during episodes preceding the Plio‐Pleistocene glaciations. The Makassar Strait forms a biogeographical barrier hindering eastward dispersal, corresponding to part of Wallace's Line in the terrestrial realm. Areas of maximum diversity of mangrove plants and their associated molluscs do not coincide closely. © 2013 The Natural History Museum. Biological Journal of the Linnean Society © 2013 The Linnean Society of London, 2013, 110 , 564–580.     

A multilocus sequencing approach reveals the cryptic phylogeographical history of Phyllodoce nipponica Makino (Ericaceae)

Discordant phylogeographical patterns among species with similar distributions may not only denote specific biogeographical histories of different species, but also could represent stochastic variance of genealogies in applied genetic markers. A multilocus investigation representing different genomes can be used to address the latter concern, allowing robust inference to biogeographical history. In the present study, we conducted a multilocus phylogeographical analysis to re‐examine the genetic structuring of Phyllodoce nipponica, in which chloroplast (cp)DNA markers exhibited a discordant pattern compared to those of other alpine plants. The geographical structure of sequence variation at five nuclear loci was not consistent with that of cpDNA and showed differentiation between the northern and southern parts of the range of this species. Its demographic history inferred from the isolation‐with‐migration model suggests that the north–south divergence originated from Pleistocene vicariance. In addition, the demographic parameters showed a lack of chloroplast‐specific gene flow, suggesting that stochastic variance in genealogy resulted in the discordant geographical structure. Thus, P. nipponica probably experienced Pleistocene vicariance between its southern and northern range parts in concordance with other alpine plants in the Japanese archipelago. The findings of the present study demonstrates the importance of using a multilocus approach for inferring population dynamics, as well as for reconciling discordant phylogeographical patterns among species. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 214–226.     

The role of disjunction and postglacial population expansion on phylogeographical history and genetic diversity of the circumboreal plant Chamaedaphne calyculata

In the last decade a number of studies has illustrated quite different phylogeographical patterns amongst plants with a northern present‐day geographical distribution, spanning the entire circumboreal region and/or circumarctic region and southern mountains. These works, employing several marker systems, have brought to light the complex evolutionary histories of this group. Here I focus on one circumboreal plant species, Chamaedaphne calyculata (leatherleaf), to unravel its phylogeographical history and patterns of genetic diversity across its geographical range. A survey of 29 populations with combined analyses of chloroplast DNA (cpDNA), internal transcribed spacer (ITS) and AFLP markers revealed structuring into two groups: Eurasian/north‐western North American, and north‐eastern North American. The present geographical distribution of C. calyculata has resulted from colonization from two putative refugial areas: east Beringia and south‐eastern North America. The variation of chloroplast DNA (cpDNA) and ITS sequences strongly indicated that the evolutionary histories of the Eurasian/north‐western North American and the north‐eastern North American populations were independent of each other because of a geographical disjunction in the distribution area and ice‐sheet history between north‐eastern and north‐western North America. Mismatch analysis using ITS confirmed that the present‐day population structure is the result of rapid expansion, probably since the last glacial maximum. The AFLP data revealed low genetic diversity of C. calyculata (P = 19.5%, H = 0.085) over the whole geographical range, and there was no evidence of loss of genetic diversity within populations in the continuous range, either at the margins or in formerly glaciated and nonglaciated regions. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 761–775.     

Phylogeography of the Trans‐Volcanic bunchgrass lizard (Sceloporus bicanthalis) across the highlands of south‐eastern Mexico

We quantify the population divergence processes that shaped population genetic structure in the Trans‐Volcanic bunchgrass lizard (Sceloporus bicanthalis) across the highlands of south‐eastern Mexico. Multilocus genetic data from nine nuclear loci and mitochondrial (mt)DNA were used to estimate the population divergence history for 47 samples of S. bicanthalis. Bayesian clustering methods partitioned S. bicanthalis into three populations: (1) a southern population in Oaxaca and southern Puebla; (2) a population in western Puebla; and (3) a northern population with a broad distribution across Hidalgo, Puebla, and Veracruz. The multilocus nuclear data and mtDNA both supported a Late Pleistocene increase in effective population size, and the nuclear data revealed low levels of unidirectional gene flow from the widespread northern population into the southern and western populations. Populations of S. bicanthalis experienced different demographic histories during the Pleistocene, and phylogeographical patterns were similar to those observed in many co‐distributed highland taxa. Although we recommend continuing to recognize S. bicanthalis as a single species, future research on the evolution of viviparity could gain novel insights by contrasting physiological and genomic patterns among the different populations located across the highlands of south‐eastern Mexico. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 852–865.     

Phylogeography of a subalpine tall‐herb Ranunculus platanifolius (Ranunculaceae) reveals two main genetic lineages in the European mountains

A phylogeographical analysis of Ranunculus platanifolius, a typical European subalpine tall‐herb species, indicates the existence of two main genetic lineages based on amplified fragment length polymorphism (AFLP) markers. One group comprises populations from the Balkan Peninsula and the south‐eastern Carpathians and the other includes the remaining part of the range of the species, encompassing the western Carpathians, Sudetes, Alps, Pyrenees and Scandinavia. The main phylogeographical break observed in this species runs across the Carpathians and separates the main parts of this range (western and south‐eastern Carpathians), supporting a distinct glacial history of populations in these areas. The high genetic similarity of the Balkan Peninsula and south‐eastern Carpathian populations could indicate a common glacial refugium for these contemporarily isolated areas of species distribution. The western and northern part of the species range displays an additional weak differentiation into regional phylogeographical groups, which could have been shaped by isolation in glacial refugia or even by a postglacial isolation. The observed weak phylogeographical structure could also be linked with ecological requirements, allowing survival along streams in relatively low, forested mountain ranges. © 2013 The Linnean Society of London     

The phylogeographical and population genetic approach to the investigation of the genetic diversity patterns in self‐incompatible clonal and polyploid Linnaea borealis subsp. borealis

Surveys of genetic diversity patterns of self‐incompatible clonal polyploid plant species are still scarcer than those of diploid plant species. Therefore, I studied the phylogeographical history of Linnaea borealis subsp. borealis to shed light on the colonization history of this clonal self‐incompatible polyploid plant in Eurasia using selected regions of plastid DNA and genetic diversity patterns of 22 populations of this species employing AFLP markers. I also addressed the question of whether the genetic diversity patterns in L. borealis subsp. borealis in Eurasia are similar to those of earlier published studies of clonal self‐incompatible diploid or polyploid plants. This survey revealed that the shallow phylogeographical history (six plastid haplotypes forming one haplogroup, 100% bootstrap support) and moderate genome‐wide diversity estimated using AFLP markers (Frag_poly = 10.8–38.9%, I = 0.060–0.180, F_ST = 0.289) were general characteristics of L. borealis subsp. borealis in its Eurasian range. The sampling strategy, in most cases at 1–2‐m or even 3–5‐m intervals, showed that a balance between vegetative and sexual reproduction and limited pollen dispersal among compatible mates can be important for genetic diversity patterns in populations of this taxon. Despite the fact that one‐half of the investigated populations were strongly isolated, they still preserved similar levels of genetic diversity across the geographical range. I found no support for the hypothesis that a bottleneck and/or inbreeding had accompanied habitat fragmentation as factors shaping genetic diversity. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 64–76.     

Phylogeography of the humbug damselfish,Dascyllus aruanus (Linnaeus, 1758): evidence of Indo‐Pacific vicariance and genetic differentiation of peripheral populations

The phylogeographical structure of coral‐associated reef fishes may have been severely affected, more than species from deeper habitats, by habitat loss during periods of low sea level. The humbug damselfish, Dascyllus aruanus, is widely distributed across the Indo‐West Pacific, and exclusively inhabits branching corals. We used mitochondrial cytochrome b sequence and seven microsatellite loci on D. aruanus samples (260 individuals) from 13 locations across the Indo‐West Pacific to investigate its phylogeographical structure distribution‐wide. A major genetic partition was found between the Indian and Pacific Ocean populations, which we interpret as the result of geographical isolation on either side of the Indo‐Pacific barrier during glacial periods. The peripheral populations of the Red Sea and the Society Islands exhibited lower genetic diversity, and substantial genetic differences with the other populations, suggesting relative isolation. Thus, vicariance on either side of the Indo‐Pacific barrier and peripheral differentiation are considered to be the main drivers that have shaped the phylogeographical patterns presently observed in D. aruanus. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 931–942.     

Phylogeographical structure of the boreal‐montane orchid Malaxis monophyllos as a result of multi‐directional gene flow

We investigated the phylogeographical structure of the boreal‐montane orchid Malaxis monophyllos in its Eurasian geographical range. We analysed four sequences of plastid DNA (trnL, trnL–trnF, rps16 and accD‐psaI), resulting in 19 haplotypes and revealing a high level of intraspecific diversity (H_D = 0.702 and π = 0.196 × 10⁻²), but showing a lack of phylogeographical structure. This pattern might be caused by multiple phenomena and processes, e.g. broad‐fronted recolonization with accompanying multi‐directional gene flow between populations and expansion from at least two refugial areas. Despite the lack of phylogeographical structure, three centres of haplotype diversity were indicated in the European part of the range of M. monophyllos. According to these data, alpine and lowland glacial refugia located between the ice sheets in the European Alps and the Scandinavian glaciers seem most likely to be in Europe. Moreover, models of climatically suitable areas during the Last Glacial Maximum (LGM) confirmed the Alps as a possible refuge, and indicated an opportunity for the persistence of M. monophyllos populations in Beringia and parts of Siberia. Using two models [Model for Interdisciplinary Research on Climate (MIROC) and Community Climate System Model (CCSM)], we predicted a significant reduction in climatically suitable areas for M. monophyllos in the future (2080). Our study also demonstrated that the biological features of M. monophyllos, including breeding system and dispersal mode, seem to be crucial in understanding its phylogeographical pattern. Our results also highlighted the importance of anthropogenic habitats as reservoirs of genetic diversity and alternative habitats for this species in the context of declining natural populations. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178 , 138–154.     

Trophic behaviour of juvenile reef fishes inhabiting interlinked mangrove–seagrass habitats in offshore mangrove islets

Stable isotope (δ¹³C and δ¹⁵N) and gut content analyses were used to investigate size‐related feeding habits of four reef fishes (the beaugregory Stegastes leucostictus, the french grunt Haemulon flavolineatum, the schoolmaster snapper Lutjanus apodus and the yellowtail snapper Ocyurus chrysurus) inhabiting an offshore (non‐estuarine) mangrove islet off Belize, Central America. Comparisons of isotopic niche space and Schoener diet similarity index suggested a low to moderate degree of niche overlap between fish size groups. The δ¹³C gradient between mangrove and seagrass prey as well as results of Bayesian mixing models revealed that sampled fishes relied mostly on seagrass prey items. Only small and large juveniles of the carnivorous species L. apodus derived a part of their diet from mangroves by targeting mangrove‐associated Grapsidae crabs and fish prey, respectively. Isotopic niche shifts were particularly obvious for carnivorous fishes that ingested larger prey items (Xanthidae crabs and fishes) during their ontogeny. The utilization of mangrove food resources is less than expected and depends on the ecology and life history of the fish species considered. This research highlights that mangrove‐derived carbon contributed relatively little to the diets of four fish taxa from an offshore mangrove islet.     

Cryptic diversity in a widespread live‐bearing fish (Poeciliidae: Belonesox)

Belonesox belizanus Kner (Teleostei: Poeciliidae) is a wide‐spread livebearing species that occurs on the Atlantic Slope of Central America from southern Mexico to northern Costa Rica. Previous work has noted morphological variation within the species, and recognized two subspecies: Belonesox belizanus belizanus and Belonesox belizanus maxillosus. We used 1122 bp of cytochrome b and 617 bp of S7‐1 DNA to conduct a phylogeographical study of Belonesox, aiming to examine the genetic distinctiveness of these taxa and other populations of Belonesox throughout the range. Bayesian phylogenetic and haplotype analyses indicated that B. b. maxillosus is not distinctive from other northern populations of Belonesox. However, a distinct phylogeographical break is evident near the Rio Grande in southern Belize. One clade comprises the putative B. b. maxillosus and all populations sampled north of the Rio Grande. The other clade comprises the Rio Grande and all populations south thereof. Fossil‐calibrated divergence time estimates suggest that isolation of the northern and southern lineages of Belonesox occurred approximately 14.1 Mya. The phylogeographical structure recovered in the present study is interesting, considering that relatively few studies have examined molecular variation across this portion of Middle America in a time‐calibrated framework. Furthermore, the present study suggests that more work is needed to adequately understand the factors that have shaped diversity of this region. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 848–860.     

Phylogeography of a mite,Halozetes fulvus,reflects the landscape history of a young volcanic island in the sub‐Antarctic

Previous studies of the microarthropods of Marion Island, Southern Ocean, documented high mitochondrial COI (cytochrome c oxidase subunit I) haplotype diversity and significant genetic structure, which were ascribed to landscape subdivision. In this paper we revisit these ideas in light of new geomorphological evidence indicating a major lineament orientated along N26.5°E. Using the microarthropod Halozetes fulvus, we test the hypothesis that the eastern and western sides of the island show different population genetic patterns, corresponding to the previously unrecognized geological separation of these regions, and perhaps also with differences in climates across the island and further landscape complexity. Mitochondrial COI data were collected for 291 H. fulvus individuals from 30 localities across the island. Notwithstanding our sampling effort, haplotype diversity was under‐sampled as indicated by rarefaction analyses. Overall, significant genetic structure was found across the island as indicated by Φ_ST analyses. Nested clade phylogeographical analyses suggested that restricted gene flow (with isolation‐by‐distance) played a role in shaping current genetic patterns, as confirmed by Mantel tests. At the local scale, coalescent modelling revealed two different genetic patterns. The first, characterizing populations on the south‐western corner of the island, was that of low effective population size and high gene flow. The converse was found on the eastern side of Marion Island. Taken together, substantial differences in spatial genetic structure characterize H. fulvus populations across Marion Island, in keeping with the hypothesis that the complex history of the island, including the N26.5°E geological lineament, has influenced population genetic structure. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 131–145.     

Intraspecific divergences of Rhodiola alsia (Crassulaceae) based on plastid DNA and internal transcribed spacer fragments

In the present study, we used two maternally inherited plastid DNA intergenic spacers, rpl20‐rps12 and trnS‐trnG, and the biparentally inherited nuclear ribosomal internal transcribed spacer (ITS) region to explore genetic variation and phylogeographical history of Rhodiola alsia, a herb endemic to the Qinghai‐Tibetan Plateau (QTP). Based on range‐wide sampling (18 populations and 227 individuals), we detected 45 plastid DNA haplotypes and 19 ITS sequence types. Only three plastid DNA haplotypes were widespread; most haplotypes were restricted to single sites or to neighbouring populations. Analysis of molecular variance revealed that most of the genetic variance was found within populations (51.24%) but that populations were also distinct (F_ST = 0.48759). We found three areas with relatively high plastid DNA diversity and these could further be recognized as potentially isolated divergence centres based on the ITS sequence type distribution. These represent three potentially isolated glacial refugia for R. alsia: one of them has long been recognized as an important refugium on the south‐eastern edge of the QTP, whereas the others are new and located in the north and south of the Tanggula Mountains on the plateau platform. Divergence time estimates based on ITS suggest that the main lineages of R. alsia diverged from each other 0.35–0.87 Mya, indicating that climatic oscillations during the Pleistocene may have been an important driver of intraspecific divergence in R. alsia. Rhodiola alsia probably experienced a phylogeographical history of retreat to isolated glacial refugia during Quaternary glaciations that led to different degrees of allopatric intraspecific divergence. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168 , 204–215.     

Climatic oscillations shape the phylogeographical structure of Atlantic Forest fire‐eye antbirds (Aves: Thamnophilidae)

In the present study, mitochondrial (mt)DNA sequence data were used to examine the genetic structure of fire‐eye antbirds (genus Pyriglena) along the Atlantic Forest and the predictions derived from the river hypothesis and from a Last Glacial Maximum Pleistocene refuge paleomodel were compared to explain the patterns of genetic variation observed in these populations. A total of 266 individuals from 45 populations were sampled over a latitudinal transect and a number of phylogeographical and population genetics analytical approaches were employed to address these questions. The pattern of mtDNA variation observed in fire‐eye antbirds provides little support for the view that populations were isolated by the modern course of major Atlantic Forest rivers. Instead, the data provide stronger support for the predictions of the refuge model. These results add to the mounting evidence that climatic oscillations appear to have played a substantial role in shaping the phylogeographical structure and possibly the diversification of many taxa in this region. However, the results also illustrate the potential for more complex climatic history and historical changes in the geographical distribution of Atlantic Forest than envisioned by the refuge model. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 900–824.     

Adaptive divergence in Darwin's small ground finch (Geospiza fuliginosa): divergent selection along a cline

We examine here, in a single year (2005), phenotypic divergence along a 560‐m elevation gradient in Darwin's small ground finch (Geospiza fuliginosa) in the Galápagos Islands. In this sample, four composite measures of phenotypic traits showed significant differences along the 18‐km geographical cline extending from lowlands to highlands. Compared with lowland birds, highland birds had larger and more pointed beaks, and thicker tarsi, but smaller feet and claws. Finches in an intervening agricultural zone had predominantly intermediate trait values. In a second, mark–recapture study we analyse selection on morphological traits among birds recaptured across years (2000–2005) in lowland and highland habitats. Birds were more likely to survive in the highlands and during the wet season, as well as if they had large beaks and bodies. In addition, highland birds exhibited higher survival rates if they had small feet and pointed beaks – attributes common to highland birds as a whole. Lowland birds were more likely to survive if they possessed the opposite traits. Selection therefore reinforced existing morphological divergence, which appears to reflect local adaptation to differing resources during the predominantly drought‐ridden conditions that characterized the 5‐year study. Alternative explanations – including genetic drift, matching habitat choice, deformation by parasites, and the effects of wear – received little or no support. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 45–59.     

Molecular phylogenetics and diversification within one of the most geographically variable bird species complexes Pachycephala pectoralis/melanura

The golden‐mangrove whistler complex Pachycephala pectoralis/melanura is, with 66 named populations, described as the most complex avian example of geographic variation in the World. It represents a well‐known example of niche differentiation where one species P. pectoralis is found on faunistically rich larger islands (and mainland) and the other P. melanura is confined to adjacent, faunistically poor islets. Except for a comparison of some Solomon Island populations, the relationships among these taxa have not been tested using molecular data. Here we combine a dense taxon sampling (22 populations of 12 named taxa distributed east of New Guinea and in Australia), with molecular data (two nuclear and two mitochondrial markers) to unravel more of the evolutionary history behind the golden whistler complex. In particular we examine relationships between Pachycephala melanura, and the very similar‐looking P. citreogaster (Bismarcks Islands) and P. pectoralis (Australia). We demonstrate that a well‐supported group of golden whistlers inhabit the Bismarck Islands and that several small islets in the immediate vicinity are inhabited by another monophyletic group consisting of P. melanura, mangrove golden whistler.     

Multiple glacial refugia and postglacial colonization routes inferred for a woodland geophyte,Cyclamen purpurascens: patterns concordant with the Pleistocene history of broadleaved and coniferous tree species

The phylogeographical history of mid‐altitude woodland herbs that depend on moist and shaded forest habitats is poorly understood. Here, we analysed the genetic structure of Cyclamen purpurascens, a mountainous calcicolous perennial, to test hypotheses regarding its glacial survival in single or multiple refugia and postglacial colonization routes, and to explore how they are congruent with the histories inferred for temperate trees and other mountainous herbs. We gathered AFLP data and chloroplast DNA sequences (trnD‐trnT region) from 68 populations spanning the entire distribution range (the Jura Mountains, Alps, western Carpathians, Dinarides). Both genetic markers revealed two main phylogeographical groups (phylogroups) in C. purpurascens. Additionally, AFLP data detected a more detailed structure of five phylogroups: two widespread, showing east?west geographical separation, and three local ones, restricted to somewhat disjunct, marginal regions of the species range. We suggest that C. purpurascens survived the last glaciation in two main regions, the foothills of the Southern Limestone Alps and the Karst area of the north‐western Dinarides, and possibly also in microrefugia in the Western Carpathians. The glacial persistence and colonization routes of this woodland herb are highly concordant with those inferred for several temperate trees, especially the European beech. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 741–760.     

Long‐term isolation and stability explain high genetic diversity in the Eastern Himalaya

China's Southwest Mountainous Region in Eastern Himalaya is a ‘biodiversity hotspot’ of global interest for conservation. Yet little is known about what has driven this unique diversity. The dramatic topography of the Southwest Mountainous Region resulting from the tectonic uplift during the late Pliocene leads to dramatic ecological stratification, which creates physical barriers to migration and isolates organisms into different subregions and mountain systems. This agrees with the observation that the phylogeographical patterns found in four species of birds (Alcippe morrisonia, Stachyridopsis ruficeps, Parus monticolus and Aegithalos concinnus) distributed in this region are characterized by deep splits between lineages that coalesce between 0.8 and 2.1 Ma. Unlike other regions at this latitude, the Southwest Mountainous Region was largely unaffected by the Pleistocene glaciations. Genetically isolated populations of these birds could thus be maintained throughout the Pleistocene in these rather stable montane environments. In comparison, we found radically different phylogeographical patterns in populations of the same four species distributed in the adjacent lowland, the Central China region. This region has a distinctly different geological history with dramatic, climate‐induced shifts in vegetation during the Pleistocene. Here, we found a considerably less geographical structure in the genetic variation and a much younger coalescence time (0.3–0.7 Ma). We also found evidence of genetic bottlenecks during the glacial periods and gene flow during the interglacial expansions. We conclude that the high genetic diversity in the Southwest Mountainous Region results from a long‐term in situ diversification within these evolutionary isolated and environment stable montane habitats.     

Allopatry and overlap in a clade of snails from mangroves and mud flats in the Indo‐West Pacific and Mediterranean (Gastropoda: Potamididae: Cerithideopsilla)

Cerithideopsilla is a genus of potamidid snails found in high abundance on sedimentary intertidal flats and beneath mangrove trees on continental shores in the tropical and subtropical Indo‐West Pacific region and Mediterranean Sea. Taxonomic revisions have recognized four species, but recent molecular studies have hinted at a higher diversity. Here, we analyse 377 individuals sampled from across the known range and use a combination of molecular phylogenetic (mitochondrial COI and 16S rRNA, and nuclear 28S rRNA genes), statistical (generalized mixed Yule‐coalescent GMYC method) and morphological (shell form) criteria to delimit 16 species. These form four species groups, corresponding with the traditionally recognized species C. alata, C. ‘djadjariensis’ (for which the valid name is C. incisa), C. cingulata and C. conica. Distribution maps were compiled using museum specimens identified by diagnostic shell characters. In combination with the molecular phylogenetic trees, these suggest an allopatric speciation mode, with diversification centred on the East Asian coastline and northern Australia, and a pronounced gap in the ‘eastern Indonesian corridor’, an area of low oceanic productivity. There is, however, frequently geographical overlap between sister species and we suggest from several sources of evidence (e.g. presence of C. conica in isolated saline lakes 900 km from the sea) that post‐speciation transport by migratory birds has occurred. Nine of the 16 species occur between the Gulf of Tonkin and Hong Kong, so southern China is significant for both the evolution and conservation of Cerithideopsilla species. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114 , 212–228.     

Small‐scale genetic structuring in a tropical cave snail and admixture with its above‐ground sister species†

We analyse the phylogeographical structure in the cave snail Georissa filiasaulae Haase & Schilthuizen, 2007 (Gastropoda: Hydrocenidae) and its above‐ground sister species G. saulae (van Benthem‐Jutting, 1966) at limestone outcrops in Sabah, Malaysian Borneo. Morphometric and 16S mitochondrial DNA data for some 220 individuals reveal strong morphological differentiation, despite ongoing unidirectional gene flow from the epigean into the hypogean environment, strong, small‐scale genetic structuring within the cave and underground dispersal between caves that were previously thought to be isolated. We discuss these results – which constitute the first phylogeographical analysis of a terrestrial cave snail – in the light of speciation in cave organisms and across ecotones in general. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 727–740.