Comparative phylogeography and species boundaries in Echinolittorina snails in the central Indo-West Pacific

Aim This study aimed to test monophyly and geographical boundaries in five marine intertidal snail species from the central Indo‐West Pacific. We tested the prediction that phylogenetic breaks between the Indian and Pacific Ocean basins should be more pronounced in continental than oceanic settings, and sought common geographical patterns of interspecific boundaries and intraspecific phylogenetic breaks in the region. Location The tropical seas of the Indo‐West Pacific. Methods We sequenced over 1200 bp of the mitochondrial cytochrome oxidase subunit I gene (COI) from 18–92 individuals sampled from throughout the ranges of each of five species of Echinolittorina (Littorinidae): three members of the Echinolittorina trochoides species complex; Echinolittorina reticulata; and Echinolittorina vidua, together with sister species, in order to test species boundaries. In addition, 630 bp of the nuclear 28S rRNA gene were sequenced from E. reticulata and its sister Echinolittorina millegrana. Phylogenetic structure was assessed using neighbour‐joining and parsimony analyses. Results COI data confirmed species boundaries and geographical distributions for all species except the pair E. reticulata and E. millegrana, which were nevertheless reciprocally monophyletic for 28S rRNA. The species from ecologically ‘continental’ habitats (E. trochoides A and E. vidua, but not E. trochoides B) mostly showed strong interoceanic breaks (with age estimates 0.58–4.4 Ma), while the ecologically ‘oceanic’E. trochoides D and E. reticulata did not. The sister species E. trochoides A and B occupy the shores of the continental shelves of Southeast Asia and Australasia respectively; between them lies the oceanic ‘eastern Indonesian corridor’ occupied by E. trochoides D and E. reticulata. The widespread continental species E. vidua showed a complex pattern of deep division into six haplotype clades with apparently parapatric distributions. Main conclusions Our results show that ecological differences (in this case continental vs. oceanic habitat) influence both intraspecific phylogenetic structure and interspecific boundaries in these snails of intertidal rocky shores. Two of the three species restricted to continental shelves show phylogenetic breaks between the Indian and Pacific Oceans, consistent with vicariant separation during Plio‐Pleistocene low sea levels. The two oceanic species do not show breaks, suggesting that they maintained interoceanic connections through the eastern Indonesian corridor. The geographical location of the interspecific boundary between continental E. trochoides A and oceanic E. trochoides D mirrors intraspecific breaks reported in other species. The sister relationship of E. trochoides A and B in Asia and Australasia, respectively, is an example of a ‘marine Wallace's line’ distribution, and we suggest that it is the result of separation of two continental species by a barrier of unsuitable oceanic habitat.     

Brazilian populations of Drosophila maculifrons (Diptera: Drosophilidae): low diversity levels and signals of a population expansion after the Last Glacial Maximum

The Quaternary period was marked by considerable changes in climate. Such palaeoclimatic changes affected the population dynamics of many species, both in the Northern and in the Southern Hemisphere. However, the extent of these impacts on the demographic patterns of Neotropical species presenting different ecological requirements remains unclear. Drosophila maculifrons DUDA 1947 belongs to the guaramunu group of Drosophila and represents a potential indicator of the genetic consequences caused by the climatic fluctuations of the Quaternary, because it seems to be sensitive to temperature and humidity shifts. The aim of this study was to evaluate the evolutionary processes subjacent to the patterns of intraspecific diversity and structure of different populations of D. maculifrons. In total, 152 individuals were collected in the south and south‐east Brazil. Phylogenetic and phylogeographical analyses were performed based on sequences of COI and COII mitochondrial genes. In general, the results pointed to Brazilian populations of D. maculifrons being extremely impoverished in terms of mitochondrial diversity and population structure, which could be explained by a recent population expansion event dated to approximately 12 000 years ago. In fact, with the assistance of species palaeo‐distribution modelling strategies, it was possible to infer that most of the sampled region did not present the D. maculifrons environmental suitability requirements at least during the period of the Last Glacial Maximum. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 55–66.     

A phylogeographical analysis across three biogeographical provinces of the south-eastern Pacific: the case of the marine gastropod Concholepas concholepas

Aim The present‐day population structure of a species reflects the influence of population history as well as contemporary processes. Little is known about the mechanisms that have shaped the geographical distribution of genetic diversity in marine species present on the south‐eastern Pacific (SEP) coast. Here we provide the first comprehensive phylogeographical study of a species distributed along the SEP coast by analysing the endemic and emblematic muricid gastropod Concholepas concholepas. Location The study localities were distributed along the SEP coast ranging from Matarani (11° S) to Puerto Eden (49° S), crossing three major biogeographical provinces: Peruvian Province, Intermediate Area and Magellanic Province. Methods A total of 337 specimens of C. concholepas were collected from 14 localities in the three biogeographical provinces/areas. Mitochondrial cytochrome oxidase I (COI) gene partial sequences (658 bp) were obtained and analysed using coalescence‐based methods to infer molecular diversity and phylogeographical patterns. Results Across the 337 individuals, we found a large diversity, with a total of 179 haplotypes at the COI gene fragment. Although a slight decrease in gene diversity was observed from north to south, an analysis of molecular variance did not reveal any significant spatial population differentiation from Peru to the tip of Chile, not even across the recognized biogeographical boundaries at 30° S and 42° S. In addition, a star‐like haplotype network suggested the past occurrence of a rapid demographic and geographical expansion over the total range examined. Calculations of the onset of this expansion suggest that it might be due to climatic conditions during the period of the marine isotope stage 11 (MIS 11, 400,000 years ago), the longer and warmer interglacial episode during the Pleistocene epoch. Main conclusions Our phylogeographical analyses indicate that in the recent past C. concholepas mitochondrial DNA lineages underwent a sudden population expansion event. In addition, our data do not support the hypothesis of concordance between biogeographical barriers and phylogeographical breaks along the SEP coast. These two results are in accordance with the paradigm of high larval dispersal ability in marine species with an extended pelagic larval phase.     

Phylogeny and phylogeography of the Lozekia–Kovacsia species group (Gastropoda: Hygromiidae)

The Lozekia–Kovacsia species group comprises three species of high conservation concern, Lozekia transsilvanica (Westerlund, 1876), Lozekia deubeli (M. Kimakowicz, 1890) and Kovacsia kovacsi ( Varga and L. Pintér, 1972 ), which occupy relatively small ranges in the Carpathian‐Pannonian region. Despite their conservation concern, the phylogeny and biogeographical history of these species have not been studied by molecular methods up to now. This study, based on mitochondrial cytochrome oxidase subunit I gene sequences, has two main objectives: (i) to infer the phylogenetic relationships within the group in order to test the latest morphology‐based system, proposed by Nordsieck [1993, Das System der paläarktischen Hygromiidae (Gastropoda: Stylommatophora: Helicoidea). Arch Molluskenkunde 122:1] and (ii) to reconstruct the distribution history of the three species. The monophyly and thus the systematic distinctness of the three species was confirmed, but our findings do not support the monophyly of the Lozekia genus and therefore contradict the current system of the species group. Genetic diversity was found to be much higher within L. deubeli than within the other two species, a possible explanation of this phenomenon is that L. transsilvanica and K. kovacsi are more recently evolved, younger species. Nested clade phylogeographycal analysis showed that the three species evolved by fragmentation events; probably L. deubeli and the ancestor of the other two species split first. At the intraspecific level, fragmentation events, as well as range expansion, played a significant role in the biogeographical history of this species group. As our findings are based on a single mitochondrial gene, we feel premature to propose changes in the generally accepted system and nomenclature. Further molecular phylogenetic analyses, also involving nuclear DNA sequences, should clarify if the evolutionary scenario suggested by our data is valid, and the three species can indeed be placed within the same genus, Lozekia.     

Intraspecific phylogeography in the sedge frog Litoria fallax (Hylidae) indicates pre-Pleistocene vicariance of an open forest species from eastern Australia

The eastern sedge frog Litoria fallax (Anura: Hylidae) is common throughout the open forests and coastal wetlands along the eastern coast of Australia. Its range spans four biogeographical zones from northern Queensland to central New South Wales. Phylogenetic analysis of mitochondrial DNA (mtDNA) haplotypes of 87 L. fallax individuals from 22 populations identified two major mtDNA lineages, differing by 11-12% sequence divergence. The two clades of haplotypes were separated by the McPherson Range, indicating that this mesic upland area has acted as a major long-term barrier to gene flow for this open forest species. Slight isolation by distance was observed within both the northern and southern lineages but was insufficient to explain the large sequence divergence between lineages. Within the northern lineage, additional phylogeographical structure was observed across the relatively dry Burdekin Gap which separates Atherton populations from all populations in the central and eastern Queensland biogeographical zones. There was less phylogeographical structure in the southern lineage suggesting historical gene flow across the drier portions of the Great Dividing Range. These data, together with recent observations of deep phylogeographical divergences in rainforest-restricted Litoria suggest that the east coast hylids of Australia represent an old (Tertiary) radiation. Individual species of Litoria have been strongly affected by climatic and ecological barriers to gene flow during the Quaternary.     

Avian host composition,local speciation and dispersal drive the regional assembly of avian malaria parasites in South American birds

Identifying the ecological factors that shape parasite distributions remains a central goal in disease ecology. These factors include dispersal capability, environmental filters and geographic distance. Using 520 haemosporidian parasite genetic lineages recovered from 7,534 birds sampled across tropical and temperate South America, we tested (a) the latitudinal diversity gradient hypothesis and (b) the distance–decay relationship (decreasing proportion of shared species between communities with increasing geographic distance) for this host–parasite system. We then inferred the biogeographic processes influencing the diversity and distributions of this cosmopolitan group of parasites across South America. We found support for a latitudinal gradient in diversity for avian haemosporidian parasites, potentially mediated through higher avian host diversity towards the equator. Parasite similarity was correlated with climate similarity, geographic distance and host composition. Local diversification in Amazonian lineages followed by dispersal was the most frequent biogeographic events reconstructed for haemosporidian parasites. Combining macroecological patterns and biogeographic processes, our study reveals that haemosporidian parasites are capable of circumventing geographic barriers and dispersing across biomes, although constrained by environmental filtering. The contemporary diversity and distributions of haemosporidian parasites are mainly driven by historical (speciation) and ecological (dispersal) processes, whereas the parasite community assembly is largely governed by host composition and to a lesser extent by environmental conditions.     

Asymmetric dispersal of southern bull‐kelp (Durvillaea antarctica) adults in coastal New Zealand: testing an oceanographic hypothesis

Coastal populations are often connected by unidirectional current systems, but the biological effects of such asymmetric oceanographic connectivity remain relatively unstudied. We used mtDNA analysis to determine the phylogeographic origins of beach‐cast bull‐kelp (Durvillaea antarctica) adults in the Canterbury Bight, a 180 km coastal region devoid of rocky‐reef habitat in southern New Zealand. A multi‐year, quantitative analysis supports the oceanographically derived hypothesis of asymmetric dispersal mediated by the north‐flowing Southland Current. Specifically, 92% of beach‐cast specimens examined had originated south of the Bight, many drifting north for hundreds of kilometres, and some traversing at least 500 km of ocean from subantarctic sources. In contrast, only 8% of specimens had dispersed south against the prevailing current, and these counter‐current dispersers likely travelled relatively small distances (tens of kilometres). These data show that oceanographic connectivity models can provide robust estimates of passive biological dispersal, even for highly buoyant taxa. The results also indicate that there are no oceanographic barriers to kelp dispersal across the Canterbury Bight, indicating that other ecological factors explain the phylogeographic disjunction across this kelp‐free zone. The large number of long‐distance dispersal events detected suggests drifting macroalgae have potential to facilitate ongoing connectivity between otherwise isolated benthic populations.     

Comparative phylogeography among hydrothermal vent species along the East Pacific Rise reveals vicariant processes and population expansion in the South

The use of sequence polymorphism from individual mitochondrial genes to infer past demography has recently proved controversial because of the recurrence of selective sweeps acting over genes and the need for unlinked multilocus data sets. However, comparative analyses using several species for one gene and/or multiple genes for one species can serve as a test for potential selective effects and clarify our understanding of historical demographic effects. This study compares nucleotide polymorphisms in mitochondrial cytochrome oxidase I across seven deep-sea hydrothermal vent species that live along the volcanically active East Pacific Rise. Approximate Bayesian Computation (ABC) method, developed to trace shared vicariant events across species pairs, indicates the occurrence of two across species divergence times, and suggests that the present geographical patterns of genetic differentiation may be explained by two periods of significant population isolation. The oldest period dates back 11.6 Ma and is associated with the vent limpet Lepetodrilus elevatus , while the most recent period of isolation is 1.3 Ma, which apparently affected all species examined and coincides with a transition zone across the equator. Moreover, significant negative Tajima's D and star-like networks were observed for all southern lineages, suggesting that these lineages experienced a concomitant demographic and geographical expansion about 100 000–300 000 generations ago. This expansion may have initiated from a wave of range expansions during the secondary colonization of new sites along the Southern East Pacific Rise (founder effects below the equator) or recurrent bottleneck events because of the increase of eruptive phases associated with the higher spreading rates of the ridge in this region.     

The odd couple: contrasting phylogeographic patterns in two sympatric sibling species of woodlouse‐hunter spiders in the Canary Islands

Comparative phylogeography seeks for commonalities in the spatial demographic history of sympatric organisms to characterize the mechanisms that shaped such patterns. The unveiling of incongruent phylogeographic patterns in co‐occurring species, on the other hand, may hint to overlooked differences in their life histories or microhabitat preferences. The woodlouse‐hunter spiders of the genus Dysdera have undergone a major diversification on the Canary Islands. The species pair Dysdera alegranzaensis and Dysdera nesiotes are endemic to the island of Lanzarote and nearby islets, where they co‐occur at most of their known localities. The two species stand in sharp contrast to other sympatric endemic Dysdera in showing no evidence of somatic (non‐genitalic) differentiation. Phylogenetic and population genetic analyses of mitochondrial cox1 sequences from an exhaustive sample of D. alegranzaensis and D. nesiotes specimens, and additional mitochondrial (16S, L1, nad1) and nuclear genes (28S, H3) were analysed to reveal their phylogeographic patterns and clarify their phylogenetic relationships. Relaxed molecular clock models using five calibration points were further used to estimate divergence times between species and populations. Striking differences in phylogeography and population structure between the two species were observed. Dysdera nesiotes displayed a metapopulation‐like structure, while D. alegranzaensis was characterized by a weaker geographical structure but greater genetic divergences among its main haplotype lineages, suggesting more complex population dynamics. Our study confirms that co‐distributed sibling species may exhibit contrasting phylogeographic patterns in the absence of somatic differentiation. Further ecological studies, however, will be necessary to clarify whether the contrasting phylogeographies may hint at an overlooked niche partitioning between the two species. In addition, further comparisons with available phylogeographic data of other eastern Canarian Dysdera endemics confirm the key role of lava flows in structuring local populations in oceanic islands and identify localities that acted as refugia during volcanic eruptions.     

The provenance of the Greek land snail species Isabellaria pharsalica: molecular evidence of recent passive long-distance dispersal

Aim The slowly dispersing Greek land snail species Isabellaria (Carinigera) pharsalica ( Nordsieck, 1974 ) can be readily distinguished from related species of the subgenus Carinigera on biogeographical grounds, i.e. by a separation of nearly 200 km. Nevertheless, I. pharsalica shows overlap in shell morphology with Isabellaria (Carinigera) buresi (A. J. Wagner, 1927). The aim of this paper is to study the interrelationships and phylogeography of I. pharsalica and selected I. buresi subspecies, in order to reconcile these apparently contradictory observations. Location Northern Greece, Macedonia, Serbia and southern Bulgaria. Methods Mitochondrial COI genealogical interrelationships were studied for specimens of I. pharsalica, selected I. buresi subspecies and other related Isabellaria species. Results COI sequences of I. pharsalica constitute a clade nested among sequences of I. buresi from north‐eastern Greece and adjacent Bulgaria. The genetic divergence among the I. pharsalica sequences is remarkably low compared to the divergence among the I. buresi sequences. Main conclusions I. pharsalica descended from specimens of I. buresi that dispersed into Thessaly, and it should therefore be classified as a subspecies within I. buresi. This find is in line with the conchological similarities between I. buresi pharsalica and other I. buresi subspecies. Given the low vagility of the snails in question and the c. 200‐km separation by land and sea between the ranges of I. buresi pharsalica and the combined range of the other I. buresi subspecies, passive dispersal of the I. pharsalica ancestors is most likely. Since the inferred area of origin of these hypothetical ancestors of I. buresi pharsalica nearly coincides with an ancient marble quarry, human‐aided dispersal during marble transport offers a possible explanation for I. buresi pharsalica's erratic distribution.     

Subterranean archipelago in the Australian arid zone: mitochondrial DNA phylogeography of amphipods from central Western Australia

In 1998, a unique subterranean ecosystem was discovered in numerous isolated calcrete (carbonate) aquifers in the arid Yilgarn region of Western Australia. Previous morphological and genetic analyses of a subterranean water beetle fauna suggest that calcrete aquifers are equivalent to closed island habitats that have been isolated for millions of years. We tested this hypothesis further by phylogeographic analyses of subterranean amphipods (Crangonyctoidea: Paramelitidae and Hyalidae) using mitochondrial DNA sequence data derived from the cytochrome oxidase I gene. Phylogenetic analyses and population genetic analyses (samova) provided strong evidence for the existence of at least 16 crangonyctoid and six hyalid divergent mitochondrial lineages, each restricted in their distribution to a single calcrete aquifer, in support of the 'subterranean island (archipelago) hypothesis' and extending its scope to include entirely water respiring invertebrates. Sequence divergence estimates between proximate calcrete populations suggest that calcretes have been isolated at least since the Pliocene, coinciding with a major aridity phase that led to the intermittent drying of surface water. The distribution of calcretes along palaeodrainage channels and on either side of drainage divides, have had less influence on the overall phylogeographic structure of populations, with evidence that ancestral crangonyctoid and hyalid species moved between catchments multiple times prior to their isolation within calcretes. At least two potential modes of evolution may account for the diversity of subterranean amphipod populations: dispersal/vicariance of stygobitic species or colonization of calcretes by surface species and independent evolution of stygobitic characteristics.     

Comparative phylogeography of tenebrionid beetles in the Aegean archipelago: the effect of dispersal ability and habitat preference

Comparative phylogeographical studies in island archipelagos can reveal lineage-specific differential responses to the geological and climatic history. We analysed patterns of genetic diversity in six codistributed lineages of darkling beetles (Tenebrionidae) in the central Aegean archipelago which differ in wing development and habitat preferences. A total of 600 specimens from 30 islands and eight adjacent mainland regions were sequenced for mitochondrial cytochrome oxidase I and nuclear Muscular protein 20. Individual gene genealogies were assessed for the presence of groups that obey an independent coalescent process using a mixed Yule coalescent model. The six focal taxa differed greatly in the number of coalescent groups and depth of lineage subdivision, which was closely mirrored by the degree of geographical structuring. The most severe subdivision at both mitochondrial DNA and nuclear DNA level was found in flightless lineages associated with presumed stable compact-soil habitats (phrygana, maquis), in contrast to sand-obligate lineages inhabiting ephemeral coastal areas that displayed greater homogeneity across the archipelago. A winged lineage, although associated with stable habitats, showed no significant phylogenetic or geographical structuring. Patterns of nucleotide diversity and local genetic differentiation, as measured using Φ_ST and hierarchical amova , were consistent with high levels of ongoing gene flow in the winged taxon; frequent local extinction and island recolonisation for flightless sand-obligate taxa; and very low gene flow and geographical structure largely defined by the palaeogeographical history of the region in flightless compact-soil taxa. These results show that differences in dispersal rate, mediated by habitat persistence, greatly influence the levels of phylogeographical subdivision in lineages that are otherwise subjected to the same geological events and palaeoclimatic changes.     

Phylogeography of the Temminck’s Stint (Calidris temminckii): historical vicariance but little present genetic structure in a regionally endangered Palearctic wader

Aim We study the population differentiation and phylogeography of the Temminck’s Stint (Calidris temminckii). Specifically, we seek signs of past and present population size changes and dispersal events and evaluate management and conservation unit status of the populations. We also study the possibility of introgression as the origin of two mitochondrial DNA (mtDNA) lineages found and estimate the divergence time of the lineages. Location Northern Eurasia. Methods We analysed 583 bp of mtDNA control region domains I and II and 11 microsatellite loci from 13 localities throughout the breeding range. In addition, we used mitochondrial cytochrome c oxidase subunit I (COI), a barcoding gene, to search for signs of introgression. Results More population differentiation was found from microsatellites than from mtDNA, although differentiation was weak in both markers. Signs of past population growth were observed, in addition to more recent decline in some areas. Both control region and COI sequences revealed two maternal lineages coexisting in Fennoscandia and in north‐west Siberia. No signs of introgression were detected. Lineage divergence time was estimated to have occurred during the glacial periods of Pleistocene. Main conclusions Slight differences in mtDNA and microsatellite differentiation and diversity may reflect different features – such as the mutation rate and effective population size – of the markers used, or female‐biased dispersal pattern and high male site‐fidelity of the species. The coexistence of the two mitochondrial lineages is most likely a consequence of post‐glacial mixing of two refugial Pleistocene populations. Based on genetic information alone, global conservation concerns are not imminent. However, fast decline of a marginal Bothnian Bay population and the smallness and remoteness of a Central Yakutian population warrant conservation actions.     

Changing perspectives on the biogeography of the tropical South Pacific: influences of dispersal, vicariance and extinction

Aim The biogeographical patterns and drivers of diversity on oceanic islands in the tropical South Pacific (TSP) are synthesized. We use published studies to determine present patterns of diversity on TSP islands, the likely sources of the biota on these islands and how the islands were colonized. We also investigate the effect of extinctions. Location We focus on oceanic islands in the TSP. Methods We review available literature and published molecular studies. Results Examples of typical island features (e.g. gigantism, flightlessness, gender dimorphism) are common, as are adaptive radiations. Diversity decreases with increasing isolation from mainland sources and with decreasing size and age of archipelagos, corresponding well with island biogeographical expectations. Molecular studies support New Guinea/Malesia, New Caledonia and Australia as major source areas for the Pacific biota. Numerous studies support dispersal‐based scenarios, either over several 100 km (long‐distance dispersal) or over shorter distances by island‐hopping (stepping stones) and transport by human means (hitch‐hiking). Only one vicariance explanation, the eastward drift of continental fragments (shuttles) that may have contributed biota to Fiji from New Caledonia, is supported by some geological evidence, although there is no evidence for the transport of taxa on shuttle fragments. Another vicariance explanation, the existence of a major continental landmass in the Pacific within the last 100 Myr (Atlantis theory), receives little support and appears unlikely. Extinction of lineages in source areas and persistence in the TSP has probably occurred many times and has resulted in misinterpretation of biogeographical data. Main conclusions Malesia has long been considered the major source region for the biota of oceanic islands in the TSP because of shared taxa and high species diversity. However, recent molecular studies have produced compelling support for New Caledonia and Australia as alternative important source areas. They also show dispersal events, and not vicariance, to have been the major contributors to the current biota of the TSP. Past extinction events can obscure interpretations of diversity patterns.     

Phylogeny and divergence time of island tiger beetles of the genus Cylindera (Coleoptera: Cicindelidae) in East Asia

To examine the diverse colonization histories in eight tiger beetle species of the genus Cylindera (Coleoptera: Cicindelidae) on the East Asian islands, we conducted phylogenetic analyses and divergence time estimation using mitochondrial cytochome oxidase subunit I (COI) and nuclear 28S rDNA sequences. The island fauna consisted of four subgenera: Apterodela, Cicindina, Ifasina, and Cylindera. Apterodela is a flightless group with large bodies, whereas the others are fliers with small bodies. In Apterodela, the divergence among endemic species in Taiwan, Japan, and the mainland was ancient (2.1–4.7 Mya), as expected from their flightlessness. Their dispersal might have occurred across the extended landmass in East Asia during the Pliocene. In the subgenus Cicindina, Cylindera elisae has spread throughout East Asia, from which an endemic species, Cylindera bonina, was derived on the oceanic Bonin Islands during the early Pleistocene (0.9 Mya). This indicates the significance of Cylindera bonina, which is currently confined to a single island, for conservation. In the subgenus Ifasina, Cylindera kaleea is widely distributed in East Asia, and its sister species Cylindera humerula, endemic to Okinawa Island, diverged 1.0 Mya, whereas Cylindera psilica on Taiwan and the Yaeyama Islands diverged approximately 0.8 Mya. In the subgenus Cylindera, the colonization of Cylindera gracilis in Japan from the mainland occurred during the last glacial period. With the exception of C. bonina, which likely colonized new territories by flight or drifting, other dispersal events might have used land connections that occurred repeatedly during the Pliocene and Pleistocene. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 715–727.     

Distribution of the related weevil species Sitophilus oryzae and S. zeamais in Brazil

The genus Sitophilus （Coleoptera： Curculionidae） encompasses species of great economic importance as stored grain pests worldwide. Among these species, the maize and the rice weevils （Sitophilus zeamais and Sitophilus oryzae, respectively） are partic- ularly important in warmer climates. These two weevils exhibit closely morphological and ecological resemblance making difficult their proper identification and recognition of their distribution in grain-producing regions. Both species are recorded in South America and particularly in Brazil, but their respective distribution and prevalence were not yet assessed in the region. Therefore, several insect samples throughout Brazil were collected and subjected to morphological identification using male genitalia and also using molec- ular identification with species-specific primers designed for clear recognition of both the species. The primers were designed for the specific amplification of a gene fragment of the cytochrome oxidase subunit I, which exhibited high specificity during our prelimi- nary experiments with insects from six populations of known species （either S. zeamais or S. oryzae）. Both identification strategies provided the same results indicating preva- lence of the maize weevil S. zeamais throughout the country. Two hypotheses may explain such prevalence： （i） the likely host preference ofS. zeamais for maize because this is the most cultivated cereal in Brazil, and （ii） the prevalence ofS. zeamais in tropical regions as compared with S. oryzae, which is more disseminated in subtropical and temperate regions.     

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.