Cranial morphology of the California vole (Microtus californicus,Cricetidae) in a contact zone

Zones of contact between divergent biological forms within or between species are critical to the study of speciation. How characters flow across contact zones can be informative of the speciation process. To better understand this phenomenon in a mammal, we investigated cranial shape change in a contact zone between northern and southern phylogeographical groups of California voles (Microtus californicus). We took 12 linear measurements of skulls, one measurement of the mandible, and coded the presence and absence of two skull foramina for 427 specimens. In multivariate analyses, skulls within parental regions were correctly assigned more than 90% of the time. In the contact zone, 49% were classified as northern and 51% as southern, with a bimodal distribution of posterior probability values. Foraminal patterns in the contact zone were intermediate between northern and southern regions. A cline analysis for coastal populations suggested a similar centre for mitochondrial and nuclear markers, although a centre for the morphological data was offset. Cranial morphology indicates an intermediate area with overlap between the two regions, as suggested by the molecular data, with a pattern distinct from mitochondrial DNA or nuclear DNA markers. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 264–283.     

Species limits in molecular phylogenies: a cautionary tale from Australian land snails (Camaenidae: Amplirhagada Iredale, 1933)

By complementing two independent systematic studies published recently on the Western Australian land snail Amplirhagada, we compare levels of morphological variation in shells and genitalia with those in the mitochondrial markers cytochrome c oxidase (COI) and 16S to evaluate the utility of mtDNA markers for delimiting species. We found that penial morphology and mitochondrial divergence are generally highly consistent in delimiting species, while shells have little overall taxonomic utility in these snails. In addition to this qualitative correspondence, there is almost no overlap between intraspecific and interspecific genetic distances in COI, with the highest intraspecific and lowest interspecific distance being 6%. This value is twice the general level suggested as a DNA barcode threshold by some authors and higher than the best average found in stylommatophoran land snails. Although in Amplirhagada land snails DNA barcoding may provide meaningful information as a first‐pass approach towards species delimitation, we argue that this is due only to specific evolutionary circumstances that facilitated a long‐termed separate evolution of mitochondrial lineages along spatial patterns. However, because in general the amounts of morphological and mitochondrial differentiation of species depend on their evolutionary history and age, the mode of speciation, distributional patterns and ecological adaptations, and absence or presence of mechanisms that prevent gene flow across species limits, the applicability of DNA barcoding has to be confirmed by morphological studies for each single group anew. Based on evidence from both molecular and morphological markers, we describe six new species from the Bonaparte Archipelago and revise the taxonomy of a further two. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 337–362.     

Phylogeographical analysis of Ligia oceanica (Crustacea: Isopoda) reveals two deeply divergent mitochondrial lineages

Isopods of the species Ligia oceanica are typical inhabitants of the rocky intertidal of the northern European coastline. The aim of this study was to assess the genetic structure of this species using mitochondrial and nuclear sequence data. We analysed partial mitochondrial cytochrome c oxidase subunit I (CO1) and 16S rRNA gene sequence data of 161 specimens collected from ten sites ranging from Spain to Norway. For selected specimens, we also sequenced the hypervariable V7 expansion segment of the nuclear 18S rRNA gene as a supplementary marker. Furthermore, we studied the infection rate of all analysed specimens by the alphaproteobacterium Wolbachia. Our analyses revealed two deeply divergent mitochondrial lineages for Ligia oceanica that probably diverged in the late Pliocene to mid Pleistocene. One lineage comprised specimens from northern populations (‘lineage N’) and one primarily those from France and Spain (‘lineage S’). Distribution patterns of the haplotypes and the genetic distances between both lineages revealed two populations that diverged before the Last Glacial Maximum. Given that we found no homogenization of mitochondrial haplotypes, our present results also reject any influence of Wolbachia on the observed mtDNA variability. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 16–30.     

Phylogenetic relationships in brown argus butterflies (Lepidoptera: Lycaenidae: Aricia) from northwestern Europe

Lycaenid butterflies of the Aricia agestisartaxerxes complex pose an unresolved taxonomic and conservation problem in northwestern Europe. Two key issues require resolution: (i) how many species of Aricia occur in northwestern Europe and what are their distributions?; (ii) how is the morphological variation observed in northwestern Europe best explained? We investigated phylogenetic relationships and phylogeographic patterns in this species group using mitochondrial and nuclear markers in comparison with morphological variation. A 325 bp fragment of the mitochondrial cytochromeb gene was sequenced from 179 individuals representing 18 populations from the UK and Scandinavia. Seventeen enzymecoding loci were analysed from 538 individuals from the same populations. Highly congruent phylogenies between mitochondrial and allozyme markers demonstrate that the sample is composed of two closely related species, A. agestis and A. artaxerxes. Both marker types also suggest that Scottish and northern Scandinavian A. artaxerxes populations are conspecific, and consequently do not support the endemic status of A. artaxerxes in the UK. The subspecies division of British populations of A. artaxerxes is also not supported by phylogenetic analyses. Allozyme and mitochondrial analyses cluster two populations from the Peak District, UK, differently. The former suggests that they are A. artaxerxes whilst the latter suggests they are A. agestis. Further research is required to find the reason for this disagreement, which could be associated with the different dynamics of nuclear and mitochondrial genes across a hybrid zone between the two species. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 75 , 27–37.     

Is Neoseiulus wearnei the Neoseiulus californicus of Australia?

Species of the family Phytoseiidae are known as predatory mites, some of them being used in crops to control mite pests, all around the world. Neoseiulus (=Cydnodromus) californicus is among the most commonly used Phytoseiidae species in biological control programs, especially in vineyards, orchards and vegetable fields. This species is distributed world-wide but has never been reported from Australia. On the other hand, specimens morphologically close to N. californicus have been assigned to a species called Neoseiulus wearnei, only reported from Australia. Investigations based on morphological and molecular comparisons were carried out to investigate whether these two taxa are conspecific. Morphological analyses showed no significant difference between specimens identified as N. wearnei and N. californicus. Similarly, genetic distances between these taxa were null, showing that all these specimens belong to the same species. Although it is not yet possible to conclude that all the specimens identified as N. wearnei are N. californicus, we can conclude that N. californicus is present in Australia. The information about the biology of N. californicus can thus now be applied to the Australian population of this species for biological control purposes.     

An integrative morphological and molecular diagnostics for Typhlodromus pyri (Acari: Phytoseiidae)

Tixier, M‐S., Okassa, M. & Kreiter, S. (2011). An integrative morphological and molecular diagnostics for Typhlodromus pyri (Acari: Phytoseiidae). —Zoologica Scripta, 41, 68–78. Phytoseiidae species are predators used in biological control programmes to limit mite pests out‐breaks in the world. Specific diagnostic is thus very important to ensure the success of pest management. This study aims to determine the species status of populations within the main species in vineyards and orchards: Typhlodromus (Typhlodromus) pyri, considering four molecular markers (COI, Cytb mtDNAs, 12SrRNA, ITSS) and 34 morphometrical characters. With the three mitochondrial DNA fragments considered, unexpected high genetic distances were observed between two groups, whereas both nuclear DNA and morphological analyses did not show such distinction. Furthermore, the GYMC and the 4 × rule tests emphasised the existence of a single species. Similarly, cross‐breeding experiments between specimens of the two groups showed no reproductive incompatibility. Therefore, despite the great intraspecific variation emphasised by the three mtDNA markers, we conclude that all the specimens considered belong to the same species. The present study clearly underlines the difficulty to conclude on species status using only mt markers and genetic distances, and stresses the necessity to apply multiple approaches for species definition. It also shows the confidence of the morphology for delineating this species.     

Morphological and genetic relationship of two closely‐related giant water bugs: Appasus japonicus Vuillefroy and Appasus major Esaki (Heteroptera: Belostomatidae)

The East Asian giant water bug species Appasus japonicus Vuillefroy and Appasus major Esaki are aquatic hemipteran insects whose ranges overlap, particularly in the Japanese Archipelago and on the Korean Peninsula. In rare cases, the two species co‐occur. Furthermore, they are very similar ecologically and also morphologically, making their identification extremely difficult, and the possibility of hybridization has also been suggested. In the present study, we re‐examined their taxonomic validity, and the characteristics useful for identifying them. To re‐examine the morphological traits useful for distinguishing these two species, 222 specimens of A. japonicus collected from Japan, Korea, and China, and 132 specimens of A. major from Japan and Korea, were examined. We also performed molecular phylogenetic analyses based on the mitochondrial DNA 16S rRNA and cytochrome oxidase subunit I (COI) regions and the nuclear DNA Histone 3 region. Although the two species are very similar ecologically and also morphologically, they showed significant genetic differentiation. Thus, there is likely some form of reproductive isolation acting between them. Major morphological characteristics overlap extensively between A. japonicus and A. major, and no particular trait was identified as being effective for differentiating these species. All the morphological characteristics examined overlapped between A. japonicus and A. major. However, a principal component analysis based on all of the morphological characteristics revealed that, despite the overlap between these species, it was possible to morphologically distinguish them. Therefore, a more accurate identification becomes possible using multiple characteristics rather than a single characteristic. The male genital paralobes, evaluated as the most useful morphological characteristic, was effective with 100% probability for the Japanese Appasus species. However, for the Asian (i.e. Korean) specimens, this characteristic was not useful. On the other hand, the results of molecular phylogenetic analyses based on the mitochondrial DNA 16S rRNA and COI regions and the nuclear DNA Histone 3 region clearly showed significant genetic differentiation between the two species. Notably, the results for the mitochondrial COI region strongly supported the independence of each monophyletic group (i.e. validity of each species). Therefore, DNA barcoding based on the mitochondrial DNA COI region is also considered useful for the identification of A. japonicus and A. major. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 615–643.     

Hidden species diversity of Australian burrowing snakes (Ramphotyphlops)

The worm‐like snakes (Scolecophidia; approximately 400 nominal extant species) have a conservative morphology and are among the most poorly‐known terrestrial vertebrates. Although molecular evidence has helped determine their higher‐level relationships, such data have rarely been used to discriminate among species. We generated a molecular data set for the continental Australian blindsnakes (genus Ramphotyphlops) to determine the concordance of molecular and morphological information in the taxonomic recognition of species. Our dataset included 741 specimens morphologically attributed to 27 nominal Ramphotyphlops species. We proposed species hypotheses (SHs) after analysis of sequences from a variable mitochondrial gene (cytochrome b) and examined these SHs with additional evidence from a nuclear gene (prolactin receptor) and geographical data. Although the nuclear marker was not as fast‐evolving and discriminating as the mitochondrial marker, there was congruence among the mitochondrial, nuclear, and geographical data, suggesting that the actual number of species is at least two times the current number of recognized, nominal species. Several biogeographical barriers and complex phytogeographical and geological patterns appeared to be involved in the division of some burrowing snake populations and, by consequence, in their diversification and speciation through isolation. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 427–441.     

Two synonymy cases within the genus Neoseiulella (Acari: Phytoseiidae): is the molecular evidence so evident?

Synonymy is considered as a great problem for diversity characterization and further applications, especially for biological control success with regard to the accurate identification of natural enemies. The present study focuses on two synonymy cases of natural enemies, belonging to the family Phytoseiidae, the genus Neoseiulella, specifically five species of this genus: Neoseiulella tiliarum, Neoseiulella formosa, Neoseiulella aceri, Neoseiulella squamiger, and Neoseiulella aceris. Morphological and molecular analyses [12S rRNA, cytochrome b (Cytb) mitochondrial (mt)DNA, internal transcribed spacer DNA] were applied. First, the results obtained support the synonymy of N. tiliarum and N. formosa. Second, because morphological differences (solenostomes occurrence) were observed for the first time between the type material of N. aceris and N. squamiger, the present study does not provide sufficient evidence to synomymize these two species and further analyses are required. Lastly, we assume that N. squamiger and N. aceri are synonyms. However, three groups of specimens, including N. aceri and N. squamiger, were identified by two mitochondrial DNA genes (12S rRNA and Cytb mtDNA). Therefore, the present study highlights the problems encountered when using only mitochondrial genes to diagnose species. The great mtDNA variations observed appear to reflect population differentiation (linked to plant support). This is the first time that such high intraspecific differentiation is be observed within the family Phytoseiidae. Further experiments, such as cross‐breeding and microsatellite DNA marker analyses, are planned to characterize gene flow and reproductive isolation levels within this species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 323–344.     

Morphological and mitochondrial DNA analyses indicate the presence of a hybrid zone between two species of leaf beetle (Coleoptera; Chrysomelidae) in Southern Spain

The present study reports a case where the survey of morphological and mitochondrial DNA variation among populations of a species complex of leaf beetle, the Gonioctena variabilis complex, has lead to the identification of a hybrid zone between two species of the complex in Southern Spain. The complex is divided into four species distributed around the western Mediterranean region. The four species, G. variabilis, Gonioctena aegrota, Gonioctena gobanzi, and Gonioctena pseudogobanzi, are traditionally determined by differences in the morphology of the male genitalia (aedeagus). To gain insight into the history of the speciation process within this species complex, we sampled populations in Portugal, Spain, Southern France, and Northern Italy. We sequenced a portion of the mitochondrial control region of each individual collected. A haplotype network of these sequences was found to comprise four distinct groups of sequence types, separated by a relatively large number of mutations. Moreover, in most of the samples for which morphological and molecular variation is available, there is a one‐to‐one correspondence between haplotype group, defined by mitochondrial sequence variation, and morphological groups defined on the basis of the aedeagus, showing evidence of four historically independent evolutionary units. This supports the use of the aedeagus morphology as a taxonomically informative trait in this species complex and a recent taxonomic revision upgrading four formerly subspecies, corresponding to the evolutionary units identified in the present study, to species status. However, some of the individuals from our samples in Southern Spain, morphologically identified as G. aegrota, were found to possess mitochondrial sequences typical of G. pseudogobanzi. The opposite case was also found. This suggests the presence of a zone of contact and hybridization between G. aegrota and G. pseudogobanzi. The location of this hybrid zone appears to be unusual. We identify historical scenarios that may explain our observations. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94 , 105–114.     

Canalization of body size matters for lifetime reproductive success of male predatory mites (Acari: Phytoseiidae)

The adaptive canalization hypothesis predicts that highly fitness‐relevant traits are canalized via past selection, resulting in low phenotypic plasticity and high robustness to environmental stress. Accordingly, we hypothesized that the level of phenotypic plasticity of male body size of the predatory mites Phytoseiulus persimilis (low plasticity) and Neoseiulus californicus (high plasticity) reflects the effects of body size variation on fitness, especially male lifetime reproductive success (LRS). We first generated small and standard‐sized males of P. persimilis and N. californicus by rearing them to adulthood under limited and ample prey supply, respectively. Then, adult small and standard‐sized males were provided with surplus virgin females throughout life to assess their mating and reproductive traits. Small male body size did not affect male longevity or the number of fertilized females but reduced male LRS of P. persimilis but not N. californicus. Proximately, the lower LRS of small than standard‐sized P. persimilis males correlated with shorter mating durations, probably decreasing the amount of transferred sperm. Ultimately, we suggest that male body size is more strongly canalized in P. persimilis than N. californicus because deviation from standard body size has larger detrimental fitness effects in P. persimilis than N. californicus. © 2014 The Authors. Biological Journal of the Linnean Society published by John Wiley & Sons Ltd on behalf of The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 889–899.     

Intra‐specific variability in Rhinoleucophenga punctulata populations (Diptera: Drosophilidae) from Neotropical biomes: Combined analyses of morphological and molecular data

Despite the fact that Drosophilidae is a very diverse and well‐studied taxon, the New World genus Rhinoleucophenga is yet poorly understood even in regard to species distribution and morphological variability pattern. In this sense, R. punctulata is a species widely distributed in the Neotropical region. Specimens of R. punctulata were collected from different biomes in Brazil: Pampa, Cerrado and Caatinga sensu strictu, and a southern Amazonian savannah enclave area. Geographical variations in the external body morphology and in the morphology of spermatheca were noticed among the different populations. The hypothesis that each population could be a different species was tested through molecular data. A fragment of the mitochondrial cytochrome c oxydase subunit I (COI) gene was sequenced to perform phylogenetic analyses through neighbor‐joining and Bayesian inferences. Pairwise genetic divergences of COI sequences were calculated using DNA barcode premises. The analyzed populations presented different variation levels in both morphology and molecular traits. However, new species were not proposed because the intra‐population nucleotide variations exceeded the inter‐population ones. The noticeable morphological and genetic variations revealed among the four studied populations of R. punctulata in different biomes of Brazil suggest the necessity that morphological, distributional and molecular data at the population level should be integrated into complementary datasets to better understand the biological diversity of Rhinoleucophenga through Neotropical environments.     

Morphological stasis in the Eurytemora affinis species complex (Copepoda: Temoridae)

Morphological stasis has long been regarded as one of the most challenging problems in evolutionary biology. This study focused on the copepod species complex, Eurytemora affinis, as a model system to determine pattern and degree of morphological stasis. This study revealed discordant rates of morphological differentiation, molecular evolution, and reproductive isolation, where speciation was accompanied by lack of morphological differentiation in secondary sex characters. Comparisons were made among phylogenies based on morphometrics, nuclear (allozyme) loci, and mitochondrial DNA (mtDNA) sequences from cytochrome oxidase I, for a total of 43 populations within the complex. These systematic relationships were also compared to patterns of reproductive isolation. In addition, genetic subdivision of nuclear molecular (allozyme) markers (G _ST) and quantitative (morphological) characters (Q _ST) were determined to infer evolutionary forces driving morphological differentiation. The morphometric phylogeny revealed that all clades, excluding the European clade, were morphologically undifferentiated and formed a polytomy (multifurcation). Morphometric distances were not correlated with mtDNA distances, or with patterns of reproductive isolation. In contrast, nuclear and mtDNA phylogenies were mostly congruent. Reproductive isolation proved to be the most sensitive indicator of speciation, given that two genetically and morphologically proximate populations showed evidence of hybrid breakdown. Quantitative genetic (morphological) subdivision (Q _ST = 0.162) was lower than nuclear genetic subdivision (G _ST = 0.617) for four laboratory-reared North American populations, indicating retarded evolution of morphological characters. This result contrasts with most other species, where Q _ST typically exceeds G _ST as a result of directional selection. Thus, in all but the European populations, evolution of the secondary sex characters was marked by morphological stasis, even between reproductively-isolated populations.     

Sexual dimorphism and intraspecific variation in wing size and shape of Tongeia fischeri (Lepidoptera: Lycaenidae)

Wing morphological variations are described here for the lycaenid butterfly Tongeia fischeri. A landmark‐based geometric morphometric approach based on wing venation of 197 male and 187 female butterflies collected in Japan was used to quantify wing size and shape variations between sexes and among populations. Sexual dimorphism in wing size and shape was detected. Females had significantly larger wings than males, while males showed a relatively elongated forewing with a longer apex and narrower wing tornus in comparison to females. Intraspecific variations in wing morphology among populations were revealed for the wing shape, but not wing size. Distinct wing shape differences were found in the vein intersections area around the distal part of the discal cell where median veins originated in the forewing and around the origin of the CU1 vein in the hindwing. In addition, phenotypic relationships inferred from wing shape variations grouped T. fischeri populations into three groups, reflecting the subspecies classification of the species. The spatial variability and phenotypic relationships between conspecific populations of T. fischeri detected here are generally in agreement with the previous molecular study based on mitochondrial and nuclear sequences, suggesting the presence of a phylogenetic signal in the wing shape of T. fischeri, and thus having taxonomic implications.     

The origin of two cryptic species of African desert jerboas (Dipodidae: Jaculus)

The desert biota is exposed to extreme and variable conditions that shape its evolution and diversification processes. In this respect, the Jaculus jerboas have gained the attention of researchers as a result of their broad Saharan–Arabian distribution and their high and unexplained, morphological, anatomical, and molecular variation. In the present study, mitochondrial and nuclear genealogies where used to confirm monophyly of two cryptic species: Jaculus jaculus and Jaculus deserti. The reconstructed demography showed that the evolutionary histories of the species are markedly different and that the expansion into North‐West Africa by J. deserti was more recent than that of J. jaculus. The weak ecological separation between species and the signs of recent population growth and expansion of J. deserti suggest that its sympatric occurrence with J. jaculus is recent and that these species evolved in isolated populations, after diverging around the Pliocene–Pleistocene boundary. The importance of climate changes on the Sahara Desert biota is discussed in the context of genetic diversification. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 435–445.     

Endemic evolutionary radiation of Rhagada land snails (Pulmonata: Camaenidae) in a continental archipelago in northern Western Australia

In the Dampier Archipelago of Western Australia's Pilbara Region, several locally endemic, morphologically distinctive species of Rhagada land snails occur, contrasting with the morphologically conservative species with wider distributions on the adjacent mainland. To test alternative origins of this unusual local diversity in a continental archipelago, we examined sequences of the cytochrome oxidase subunit 1 and 16S mitochondrial genes in 22 described species and eight undescribed forms, including all known morphospecies from the Pilbara Region's Dampier Archipelago and adjacent mainland. Phylogenetic analyses consistently resolved four, deep clades within the Pilbara Region, with a mean sequence divergence of 15–18%. All but one of the species from the Dampier Archipelago formed one of the major clades, indicating that the morphological radiation in the archipelago evolved locally, rather than through multiple, relictual mainland lineages. Morphological divergence spanning almost that of the entire genus was within a subclade with sequence divergence < 4%, highlighting the disconnection between morphological diversification and levels of molecular genetic divergence. This in situ morphological radiation in the Dampier Archipelago, which transcends variation seen over much larger distances on the mainland, is unusual for a continental archipelago, and may relate to local heterogeneity of land forms. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 316–327.     

Microsatellite DNA markers for the intertidal copepod Tigriopus californicus

Eleven microsatellite loci were isolated and characterized for the intertidal copepod Tigriopus californicus. Primers reliably amplify alleles in inbred lines derived from two divergent populations previously shown to have genetic distances of 18% for the mitochondrial cytochrome oxidase I gene. The 11 loci provided markers for eight of the species’ 12 chromosomes.     

Morphology of the Podarcis wall lizards (Squamata: Lacertidae) from the Iberian Peninsula and North Africa: patterns of variation in a putative cryptic species complex

Cryptic species complexes represent groups that have been classified as a single species, because of the difficulty in distinguishing its members morphologically. Morphological investigation following the discovery of cryptic diversity is crucial for describing and conserving biodiversity. Here we present a detailed account of morphological variation in a group of Iberian and North African Podarcis wall lizards of the family Lacertidae, trying to elucidate the morphological patterns observed between known mitochondrial lineages. Our results reveal very high morphological variation within lineages, considering both biometric and pholidotic traits, but also indicate that lineages are significantly different from each other. The main sources of variation, both globally and between lineages, arise from body size, head dimensions, and limb length, possibly pointing to underlying ecological mechanisms. A combination of body size, body shape, and continuous pholidotic traits allows a relatively good discrimination between groups, especially when comparing one group with the rest or pairs of groups. However, ranges of variation greatly overlap between groups, thereby not allowing the establishment of diagnostic traits. The high morphological variation observed indicates that external morphology is not particularly useful for species delimitation in this group of lizards, as local adaptation seems to play a major role in within‐ and between‐group differentiation. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 164 , 173–193.     

Molecular phylogeny of the Eremias persica complex of the Iranian plateau (Reptilia: Lacertidae), based on mtDNA sequences

The Persian racerunner Eremias persica Blanford, 1875 is confined to the Iranian plateau, and forms one of the most widespread but rarely studied species of the family Lacertidae. With many local populations inhabiting a variety of habitats, and exhibiting considerable morphological, genetic, and ecological variations, it represents a species complex. We analysed sequences of mitochondrial cytochrome b and 12S ribosomal RNA (rRNA) genes derived from 13 geographically distant populations belonging to the E. persica complex. Using our knowledge of palaeogeographical events, a molecular clock was calibrated to assess the major events in fragmentation, radiation, and intraspecific variation. The sequence data strongly support a basal separation of the highland populations of western Iran from those of the open steppes and deserts, occurring in the east. The subsequent radiation, fragmentation, and evolution of these major assemblages have led to several discernable geographical lineages across the wide area of the Iranian plateau. The results indicate a middle‐Miocene origin for the clade as a whole. The first split, isolating the western and eastern clades, appears to have occurred 11–10 Mya. Further fragmentations and divergence within the major clades began about 8 Mya, with an evolutionary rate of 1.6% sequence divergence per million years among the lineages in the genes studied (combined data set). Molecular and morphological data strongly support a taxonomic revision of this species complex. At least four of the discovered clades should be raised to species, and two to subspecies, rank. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 641–660.     

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.