Phylogeny and Phytogeography of Eupatorium (Eupatorieae, Asteraceae): Insights from Sequence Data of the nrDNA ITS Regions and cpDNA RFLP

Eupatorium were examined by sequencing the internal transcribed spacers (ITS) of nuclear ribosomal DNA and restriction site analysis of chloroplast DNA. Molecular data provided strong evidence that (1) this genus originated in North America, (2) the genus diverged into three morphological species groups, Eutrochium, Traganthes and Uncasia in North America, and (3) one of the North American Uncasia lineages migrated into temperate Europe and eastern Asia over the Bering land bridge. The estimated divergence times support a late Miocene to early Pliocene migration from North America to Eurasia via the Bering land bridge. A European species was sister to all of the eastern Asian species examined. The disjunct distribution pattern of the genus Eupatorium is incongruent with the classical Arcto-Tertiary geoflora concept. Received 13 September 1999/ Accepted in revised form 4 January 2000     

Phylogenomics,biogeography, and evolution of morphology and ecological niche of the eastern Asian–eastern North American Nyssa (Nyssaceae)

Nyssa (Nyssaceae, Cornales) represents a classical example of the well‐known eastern Asian–eastern North American floristic disjunction. The genus consists of three species in eastern Asia, four species in eastern North America, and one species in Central America. Species of the genus are ecologically important trees in eastern North American and eastern Asian forests. The distribution of living species and a rich fossil record of the genus make it an excellent model for understanding the origin and evolution of the eastern Asian–eastern North American floristic disjunction. However, despite the small number of species, relationships within the genus have remained unclear and have not been elucidated using a molecular approach. Here, we integrate data from 48 nuclear genes, fossils, morphology, and ecological niche to resolve species relationships, elucidate its biogeographical history, and investigate the evolution of morphology and ecological niches, aiming at a better understanding of the well‐known EA–ENA floristic disjunction. Results showed that the Central American (CAM) Nyssa talamancana was sister to the remaining species, which were divided among three, rapidly diversified subclades. Estimated divergence times and biogeographical history suggested that Nyssa had an ancestral range in Eurasia and western North America in the late Paleocene. The rapid diversification occurred in the early Eocene, followed by multiple dispersals between and within the Erasian and North American continents. The genus experienced two major episodes of extinction in the early Oligocene and end of Neogene, respectively. The Central American N. talamancana represents a relic lineage of the boreotropical flora in the Paleocene/Eocene boundary that once diversified in western North America. The results supported the importance of both the North Atlantic land bridge and the Bering land bridge (BLB) for the Paleogene dispersals of Nyssa and the Neogene dispersals, respectively, as well as the role of Central America as refugia of the Paleogene flora. The total‐evidence‐based dated phylogeny suggested that the pattern of macroevolution of Nyssa coincided with paleoclimatic changes. We found a number of evolutionary changes in morphology (including wood anatomy and leaf traits) and ecological niches (precipitation and temperature) between the EA–ENA disjunct, supporting the ecological selection driving trait evolutions after geographic isolation. We also demonstrated challenges in phylogenomic studies of lineages with rapid diversification histories. The concatenation of gene data can lead to inference of strongly supported relationships incongruent with the species tree. However, conflicts in gene genealogies did not seem to impose a strong effect on divergence time dating in our case. Furthermore, we demonstrated that rapid diversification events may not be recovered in the divergence time dating analysis using BEAST if critical fossil constraints of the relevant nodes are not available. Our study provides an example of complex bidirectional exchanges of plants between Eurasia and North America in the Paleogene, but “out of Asia” migrations in the Neogene, to explain the present disjunct distribution of Nyssa in EA and ENA.     

Testing concordance in species boundaries using acoustic,morphological, and molecular data in the field cricket genus Itaropsis (Orthoptera: Grylloidea,Gryllidae: Gryllinae)

In most taxa, species boundaries are inferred based on differences in morphology or DNA sequences revealed by taxonomic or phylogenetic analyses. In crickets, acoustic mating signals or calling songs have species‐specific structures and provide a third data set to infer species boundaries. We examined the concordance in species boundaries obtained using acoustic, morphological, and molecular data sets in the field cricket genus Itaropsis. This genus is currently described by only one valid species, Itaropsis tenella, with a broad distribution in western peninsular India and Sri Lanka. Calling songs of males sampled from four sites in peninsular India exhibited significant differences in a number of call features, suggesting the existence of multiple species. Cluster analysis of the acoustic data, molecular phylogenetic analyses, and phylogenetic analyses combining all data sets suggested the existence of three clades. Whatever the differences in calling signals, no full congruence was obtained between all the data sets, even though the resultant lineages were largely concordant with the acoustic clusters. The genus Itaropsis could thus be represented by three morphologically cryptic incipient species in peninsular India; their distributions are congruent with usual patterns of endemism in the Western Ghats, India. Song evolution is analysed through the divergence in syllable period, syllable and call duration, and dominant frequency. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 164 , 285–303.     

Uplift-driven diversification revealed by the historical biogeography of the cockroach Cryptocercus Scudder (Blattodea: Cryptocercidae) in eastern Asia

Cryptocercus Scudder is a genus of wingless cockroaches, which spend their lives feeding within rotting wood in old-growth montane forests. Their dispersal capability is likely to be limited because they depend on the succession of temperate forests, but their distribution exhibits intercontinental disjunctions. Although the natural history and conservation biology of the North American species of the genus have received much attention, the evolution of the eastern Asian lineages remains enigmatic. To resolve the geographic patterns and evolutionary history of Cryptocercus in eastern Asia, we analysed genetic data of species from China (27 species), Korea (one species) and the Russian Far East (one species). We performed phylogenetic analyses of seven genes to infer the evolutionary relationships among species of Asian Cryptocercus. We then used Bayesian molecular dating to estimate the evolutionary timescale of the genus. Ancestral geographic distributions were reconstructed in rasp using statistical dispersal-vicariance analysis and statistical dispersal-extinction-cladogenesis. Our maximum-likelihood and Bayesian phylogenetic trees supported four major lineages of Cryptocercus, revealing a clear geographical pattern. The divergence of American and Asian lineages was inferred to have occurred 74.8 Ma (95% credibility interval: 51.1–103.8 Ma), with the diversification of Asian taxa beginning at 30.7 Ma (95% credibility interval: 22.9–40.3 Ma). The most recent common ancestor of Asian Cryptocercus taxa was inferred to have had a broad distribution in Asia. The uplift of the Qinghai-Tibet Plateau in the Palaeogene and Neogene, along with climatic oscillations in the Quaternary, probably had substantial effects on the formation of the disjunction pattern in the Cryptocercus lineages found in the Hengduan Mountains and Qin-Daba Mountains of China. We propose that the distribution of Cryptocercus has been strongly influenced by habitat fragmentation and subsequent allopatric speciation.     

ISOZYME DIVERGENCE BETWEEN EASTERN ASIAN,NORTH AMERICAN,AND TURKISH SPECIES OF LIQUIDAMBAR (HAMAMELIDACEAE)

The deciduous woody genus Liquidambar has four morphologically similar species in eastern and western Asia, eastern North America, and Central America. Liquidambar styraciflua is found in the eastern United States and Central America, L. orientalis is native only to southwest Turkey, and L. formosana and L. acalycina occur in eastern Asia. This genus is one of many that contributes to the floristic similarities observed between these different regions. Allelic variation was scored at 22 isozyme loci from 41 populations. The level of genetic divergence between species on different continents is high. Nei's genetic identity was 0.431 between L. formosana and L. styraciflua, 0.485 between L. acalycina and L. styraciflua, 0.512 between L. orientalis and L. styraciflua, 0.256 between L. formosana and L. orientalis, and 0.305 between L. acalycina and L. orientalis. Estimates of time of divergence from the isozyme data suggest that the current species diverged before or during the Miocene. The pattern of relationships portrayed by the isozyme data suggest a longer period of separation between the eastern and western Asian forms of this genus. In addition, the eastern North American and Turkish species appear to be the most closely related intercontinental pair of species providing evidence for a North Atlantic land bridge as late as the Miocene. It would appear, therefore, that the North American populations were in contact with the Asian populations over the North Pacific and North Atlantic possibly as late as the Miocene, but that the separation between the two Asian populations occurred much earlier. The time of divergence as measured from the isozyme data correlates with an independent assessment of the origin of these disjuncts as determined from the fossil record.     

Evolutionary history of the scorpionfly Dicerapanorpa magna (Mecoptera,Panorpidae)

Climate changes can have fundamental impacts on the distributional patterns of montane species, and range shifts frequently lead to allopatric divergence followed by the establishment of secondary contact zones. Many European and North American organisms have retreated to southern refugia during glacial periods and colonized northward during postglacial periods, but little is known about the evolutionary response of cold‐adapted insects to Pleistocene climate changes in eastern Asia. The scorpionfly Dicerapanorpa magna (Chou), with cold temperate habitat preference and weak dispersal ability, provides a good model system to explore how climate changes have influenced the distribution and divergence of cold‐adapted insects in eastern Asia. This study reconstructed the demographic dynamics and evolutionary history of D. magna with phylogeographic approaches, and predicted the species’ suitable areas under the Last Glacial Maximum (LGM) and current scenarios with the ecological niche modelling analysis. The mitochondrial cytochrome c oxidase subunit I resolved three phylogenetic lineages in D. magna dating back to Pleistocene, corresponding well with the geographically isolated Qinling, Bashan and Minshan Mountains. The ecological niche modelling recovered the suitable habitats for D. magna were the Qinling and Bashan Mountains under LGM and current conditions. The three lineages of D. magna might be in a process of incipient speciation, and likely derived their current distribution from separate glacial origins, followed by vicariance and divergence.     

Lineage divergence and speciation in the Web‐toed Salamanders (Plethodontidae: Hydromantes) of the Sierra Nevada,California

Peripatric speciation and the importance of founder effects have long been controversial, and multilocus sequence data and coalescent methods now allow hypotheses of peripatric speciation to be tested in a rigorous manner. Using a multilocus phylogeographical data set for two species of salamanders (genus Hydromantes) from the Sierra Nevada of California, hypotheses of recent divergence by peripatric speciation and older, allopatric divergence were tested. Phylogeographical analysis revealed two divergent lineages within Hydromantes platycephalus, which were estimated to have diverged in the Pliocene. By contrast, a low‐elevation species, Hydromantes brunus, diverged from within the northern lineage of H. platycephalus much more recently (mid‐Pleistocene), during a time of major climatic change in the Sierra Nevada. Multilocus species tree estimation and coalescent estimates of divergence time, migration rate, and growth rate reject a scenario of ancient speciation of H. brunus with subsequent gene flow and introgression from H. platycephalus, instead supporting a more recent divergence with population expansion. Although the small, peripheral distribution of H. brunus suggests the possibility of peripatric speciation, the estimated founding population size of the species was too large to have allowed founder effects to be important in its divergence. These results provide evidence for both recent speciation, most likely tied to the climatic changes of the Pleistocene, and older lineage divergence, possibly due to geological events, and add to evidence that Pleistocene glacial cycles were an important driver of diversification in the Sierra Nevada.     

Analysis of DNA sequences of six chloroplast and nuclear genes suggests incongruence, introgression, and incomplete lineage sorting in the evolution of Lespedeza (Fabaceae)

The genus Lespedeza (Fabaceae) consists of 40 species disjunctively distributed in East Asia and eastern North America. Phylogenetic relationships of all Lespedeza species and closely related genera were reconstructed using maximum parsimony, maximum likelihood, and Bayesian analyses of sequence data from five chloroplast (rpl16, rpl32-trnL, rps16-trnQ, trnL-F, and trnK/matK) and one nuclear (ITS) DNA regions. All analyses yielded consistent relationships among major lineages. Our results suggested that Campylotropis, Kummerowia, and Lespedeza are monophyletic, respectively. Lespedeza is resolved as sister to Kummerowia and these two together are further sister to Campylotropis. Neither of the two subgenera, subgen. Lespedeza and subgen. Macrolespedeza, in Lespedeza based on morphological characters, is recovered as monophyletic. Within Lespedeza, the North American clade is retrieved as sister to the Asian clade. The nuclear and chloroplast markers showed incongruent phylogenetic signals at shallow-level phylogeny, which may point to either introgression or incomplete lineage sorting in Lespedeza. The divergence times within Lespedeza and among related genera were estimated using Bayesian approach with BEAST. It is assumed that following the divergence between Kummerowia and Lespedeza in Asia in the late Miocene, the ancestor of Lespedeza diverged into the North American and the Asian lineages. The North American ancestor quickly migrated to North America through the Bering land bridge in the late Miocene. The North American and Asian lineages started to diversify almost simultaneously in the late Miocene but resulted in biased numbers of species in two continents.     

Phylogenetic, morphological, and chemotaxonomic incongruence in the North American endemic genus Echinacea

The study of recently formed species is important because it can help us to better understand organismal divergence and the speciation process. However, these species often present difficult challenges in the field of molecular phylogenetics because the processes that drive molecular divergence can lag behind phenotypic divergence. In the current study we show that species of the recently diverged North American endemic genus of purple coneflower, Echinacea, have low levels of molecular divergence. Data from three nuclear loci and two plastid loci provide neither resolved topologies nor congruent hypotheses about species-level relationships. This lack of phylogenetic resolution is likely due to the combined effects of incomplete lineage sorting, hybridization, and backcrossing following secondary contact. The poor resolution provided by molecular markers contrasts previous studies that found well-resolved and taxonomically supported relationships from metabolic and morphological data. These results suggest that phenotypic canalization, resulting in identifiable morphological species, has occurred rapidly within Echinacea. Conversely, molecular signals have been distorted by gene flow and incomplete lineage sorting. Here we explore the impact of natural history on the genetic organization and phylogenetic relationships of Echinacea.     

Phylogenetic assessment and biogeographic analyses of tribe <Emphasis Type="Italic">Peracarpeae</Emphasis> (Campanulaceae)

Peracarpeae is a small tribe consisting of three genera: Homocodon, Heterocodon and Peracarpa, with a disjunct distribution between eastern Asia and western North America. Homocodon is endemic to southwestern China and was previously placed in the western North American genus Heterocodon. Our phylogenetic analysis using four plastid markers (matK, atpB, rbcL and trnL-F) suggests the polyphyly of Peracarpeae. Homocodon is sister to a clade consisting of the eastern Asian Adenophora, Hanabusaya and species of Campanula from the Mediterranean region and North America, rather than forming a clade with Heterocodon. Homocodon and its Eurasia relatives are estimated to have diverged in the early Miocene (16.84 mya, 95% HPD 13.35–21.45 mya). The eastern Asian Peracarpa constitutes a clade with the North American Heterocodon, Githopsis and three species of Campanula, supporting a disjunction between eastern Asia and North America in Campanulaceae. The Asian-North American disjunct lineages diverged in the early Miocene (16.17 mya, 95% HPD 13.12–20.9 mya). The biogeographic analyses suggest that Homocodon may be a relict of an early radiation in eastern Asia, and that Peracarpa and its closest North American relatives most likely originated from a Eurasian ancestor.     

Divergence,gene flow,and speciation in eight lineages of trans‐Beringian birds

Determining how genetic diversity is structured between populations that span the divergence continuum from populations to biological species is key to understanding the generation and maintenance of biodiversity. We investigated genetic divergence and gene flow in eight lineages of birds with a trans‐Beringian distribution, where Asian and North American populations have likely been split and reunited through multiple Pleistocene glacial cycles. Our study transects the speciation process, including eight pairwise comparisons in three orders (ducks, shorebirds and passerines) at population, subspecies and species levels. Using ultraconserved elements (UCEs), we found that these lineages represent conditions from slightly differentiated populations to full biological species. Although allopatric speciation is considered the predominant mode of divergence in birds, all of our best divergence models included gene flow, supporting speciation with gene flow as the predominant mode in Beringia. In our eight lineages, three were best described by a split‐migration model (divergence with gene flow), three best fit a secondary contact scenario (isolation followed by gene flow), and two showed support for both models. The lineages were not evenly distributed across a divergence space defined by gene flow (M) and differentiation (F_ST), instead forming two discontinuous groups: one with relatively shallow divergence, no fixed single nucleotide polymorphisms (SNPs), and high rates of gene flow between populations; and the second with relatively deeply divergent lineages, multiple fixed SNPs, and low gene flow. Our results highlight the important role that gene flow plays in avian divergence in Beringia.     

Contribution to the taxonomy of Gryllus Linnaeus, 1758 in South America: Part I: Redescription of Gryllus argentinus Saussure, 1874 (Orthoptera,Grylloidea, Gryllidae)

The genus Gryllus includes 82 described species that occur in America from Canada to Argentina as well as in several areas of Africa, Europe and Asia. There are 12 species in South America, which were described in the nineteenth century based on a small number of samples and inconsistent characters such as body coloration and external morphology. The aim of this article is to redescribe Gryllus argentinus Saussure, 1874 collected in the urban areas of Pelotas, Capão do Leão and Rio Grande, in the state of Rio Grande do Sul, southern Brazil, highlighting phallic sclerites, calling song and body morphometry. We designate the lectotype male, provide a combination of diagnostic characteristics and discuss the taxonomic situation of South American Gryllus species.     

Divergence between the Courtship Songs of the Field Crickets Gryllus texensis and Gryllus rubens (Orthoptera, Gryllidae)

Acoustic mating signals are often important as both interspecific prezygotic isolating mechanisms and as sexually selected traits in intraspecific mate choice. Here, we investigate the potential for cricket courtship song to act as an isolating mechanism by assessing divergence between the courtship songs of Gryllus texensis and Gryllus rubens , two broadly sympatric cryptic sister species of field crickets with strong prezygotic isolation via the calling song and little or no postzygotic isolation. We found significant species-level differences in the courtship song, but the song has not diverged to the same extent as the calling song, and considerable overlap remains between these two species. Only two related courtship song characters are sufficiently distinct to play a possible role in prezygotic species isolation.     

Biogeography and molecular phylogeny of the genus Schizothorax (Teleostei: Cyprinidae) in China inferred from cytochrome b sequences

Aim To test a vicariant speciation hypothesis derived from geological evidence of large‐scale changes in drainage patterns in the late Miocene that affected the drainages in the south‐eastern Tibetan Plateau. Location The Tibetan Plateau and adjacent areas. Methods The cytochrome b DNA sequences of 30 species of the genus Schizothorax from nine different river systems were analysed. These DNA sequences were analysed using parsimony, maximum likelihood and Bayesian methods. The approximately unbiased and Shimodaira–Hasegawa tests were applied to evaluate the statistical significance of the shortest trees relative to alternative hypotheses. Dates of divergences between lineages were estimated using the nonparametric rate smoothing method, and confidence intervals of dates were obtained by parametric bootstrapping. Results The phylogenetic relationships recovered from molecular data were inconsistent with traditional taxonomy, but apparently reflected geographical associations with rivers. Within the genus Schizothorax, we observed a divergence between the lineages from the Irrawaddy–Lhuit and Tsangpo–Parlung rivers, and tentatively dated this vicariant event back to the late Miocene (7.3–6.8 Ma). We also observed approximately simultaneous geographical splits within drainages of the south‐eastern Tibetan Plateau, the Irrawaddy, the Yangtze and the Mekong–Salween rivers in the late Miocene (7.1–6.2 Ma). Main conclusions Our molecular evidence tentatively highlights the importance of palaeoriver connections and the uplift of the Tibetan Plateau in understanding the evolution of the genus Schizothorax. Molecular estimates of divergence times allowed us to date these vicariant scenarios back to the late Miocene, which agrees with geological suggestions for the separation of these drainages caused by tectonic uplift in south‐eastern Tibet. Our results indicated the substantial role of vicariant‐based speciation in shaping the current distribution pattern of the genus Schizothorax.     

Temperature Effects on the Temporal Properties of Calling Songs in the Crickets <Emphasis Type="Italic">Gryllus fultoni</Emphasis> and <Emphasis Type="Italic">G. vernalis</Emphasis>: Implications for Reproductive Isolation in Sympatric Populations

Two closely related wood-cricket species, Gryllus fultoni (Orthoptera: Gryllidae) and G. vernalis, produce similar calling songs, consisting of 3-pulse chirps. Analysis of field and laboratory recordings of calling songs showed that, after correction to a common temperature, there was a divergence in chirp and pulse rates between far allopatric populations of G. fultoni and populations sympatric with G. vernalis. To determine whether the divergence in calling songs potentially provides reproductive isolation between G. fultoni and G. vernalis throughout the temperature range over which these insects sing, we recorded calling songs of lab-reared G. fultoni and G. vernalis populations between 18 and 28°C. Mean chirp rate significantly differed between sympatric and far allopatric G. fultoni populations as well as between sympatric G. fultoni and G. vernalis populations. Although there was a significant difference in mean pulse rate between sympatric G. fultoni and G. vernalis populations, pulse rate did not differ between sympatric and far allopatric G. fultoni populations in the laboratory study. Considering the magnitudes of differences in calling song characters discriminated by females of G. fultoni and the mean differences and the variability in calling song characters between the two species, the joint difference in chirp and pulse rates may be adequate for species discrimination over most of the range at which these crickets breed.     

Testing phylogenetic hypotheses for reconstructing the evolutionary history of Dolichopoda cave crickets in the eastern Mediterranean

Aim To investigate the molecular phylogenetic divergence and historical biogeography of cave crickets belonging to the genus Dolichopoda (Orthoptera, Rhaphidophoridae). Location Caves in continental and insular Greece. Methods We sequenced 1967 bp of mitochondrial DNA, corresponding to three fragments of the small and large subunit of the ribosomal RNA (16S and 12S rRNA, respectively) and to the subunit I of cytochrome oxidase (COI), to reconstruct phylogenetic relationships among all 30 known Greek species of Dolichopoda. Alternative hypotheses about the colonization of the Hellenic Peninsula by Dolichopoda species were tested by comparing the degree of discordance between species trees and gene trees under four plausible biogeographical scenarios. Results The present study revealed a rather well resolved phylogeny at species level, identifying a number of clades that represent long‐separated lineages and diverse evolutionary histories within the genus Dolichopoda. Two main clades were revealed within Hellenic–Aegean species, identifying a north‐western and a south‐eastern species group. Based on Bayesian analysis, we applied a relaxed molecular clock to estimate the divergence times between the lineages. The results revealed that the origins of eastern Mediterranean lineages are much older than those of previously studied western Mediterranean Dolichopoda. Tests of alternative biogeographical hypotheses showed that a double colonization of the Hellenic Peninsula, following separate continental and trans‐Aegean routes during the Messinian stage, best accounts for the present distribution of Greek Dolichopoda species. Main conclusions Reconstruction and biogeographical hypothesis testing indicated that the colonization of Greece by Dolichopoda species comprised two episodes and two different routes. The southern lineage probably arose from a trans‐Aegean colonization during the Messinian salinity crisis (5.96–5.33 Ma). The northern lineage could be the result of dispersal from the north through the Balkan Peninsula. The opening of the Mid‐Aegean Trench could have promoted an initial diversification within the uprising Anatolian Plateau, while the Messinian marine regression offered the conditions for a rapid dispersal through the whole Aegean–Hellenic region. In addition, climatic events during the Plio‐Pleistocene may have been responsible for the speciation within each of the two different phylogeographical units, principally attributable to vicariance events.     

SIBLING SPECIES,CALL DIFFERENCES,AND SPECIATION IN GREEN LACEWINGS (NEUROPTERA: CHRYSOPIDAE: CHRYSOPERLA)

Green lacewings of the morphologically homogeneous carnea-plorabunda-downesi group within the chrysopid genus Chrysoperla produce unique, species-specific, substrate-borne songs during courtship and mating; both sexes sing, and partners must reciprocally exchange their acoustical signals before copulation will occur. Two widespread, sympatric North American representatives of this complex, the sibling species pair C. plorabunda and C. downesi, hybridize readily in the laboratory but not in nature. This species pair has been presented as exemplifying sympatric speciation by disruptive selection. Here, it is shown from tape-playback and female-choice experiments that calls represent bona fide reproductive isolating mechanisms between the two species. Furthermore, call analyses of F₁, F₂, F₃, and backcross progeny of the two species confirm polygenic control of call expression, in which different alleles at each of several loci are fixed in each taxon. Sex linkage of traits is absent, but the various features of the calls are not completely independent of one another in their patterns of inheritance. These and other life-history data cast doubt on several major premises of the sympatric speciation hypothesis and suggest that call alteration might have triggered the speciation event giving rise to the siblings. A complex of cryptic “song morphs” physically and ecologically identical to C. plorabunda and C. downesi, but singing different songs, exists in the mountains of western North America, while the Alps of central Europe harbor populations of C. carnea that have undergone call differentiation in an analogous but independent manner. It is proposed that call divergence may in itself be driving the speciation process within this section of Chrysoperla, by greatly accelerating the rate at which full reproductive isolation between populations can be achieved.     

Extended phylogeny of Aquilegia: the biogeographical and ecological patterns of two simultaneous but contrasting radiations

Studies of the North American columbines (Aquilegia, Ranunculaceae) have supported the view that adaptive radiations in animal-pollinated plants proceed through pollinator specialisation and floral differentiation. However, although the diversity of pollinators and floral morphology is much lower in Europe and Asia than in North America, the number of columbine species is similar in the three continents. This supports the hypothesis that habitat and pollinator specialisation have contributed differently to the radiation of columbines in different continents. To establish the basic background to test this hypothesis, we expanded the molecular phylogeny of the genus to include a representative set of species from each continent. Our results suggest that the diversity of the genus is the result of two independent events of radiation, one involving Asiatic and North American species and the other involving Asiatic and European species. The ancestors of both lineages probably occupied the mountains of south-central Siberia. North American and European columbines are monophyletic within their respective lineages. The genus originated between 6.18 and 6.57 million years (Myr) ago, with the main pulses of diversification starting around 3 Myr ago both in Europe (1.25–3.96 Myr ago) and North America (1.42–5.01 Myr ago). The type of habitat occupied shifted more often in the Euroasiatic lineage, while pollination vectors shifted more often in the Asiatic-North American lineage. Moreover, while allopatric speciation predominated in the European lineage, sympatric speciation acted in the North American one. In conclusion, the radiation of columbines in Europe and North America involved similar rates of diversification and took place simultaneously and independently. However, the ecological drivers of radiation were different: geographic isolation and shifts in habitat use were more important in Europe while reproductive isolation linked to shifts in pollinator specialisation additionally acted in North America.     

Demographic history,geographical distribution and reproductive isolation of distinct lineages of blue rockfish (Sebastes mystinus), a marine fish with a high dispersal potential

Understanding the barriers to genetic exchange in taxonomic groups that have a high dispersal potential will provide critical information on speciation in general. Blue rockfish (Sebastes mystinus) are good taxa to examine speciation because they are nonmigratory inhabitants of shallow rocky reef habitats along the eastern North Pacific with a pelagic larval stage lasting 3–5 months. The goal of this study was to analyse the evolutionary history and distribution patterns of different lineages within S. mystinus described previously and use this information to understand the speciation process in this group of high dispersal fish. The molecular data derived from specimens sampled over approximately 1650 km of the S. mystinus range revealed a northerly and southerly distribution for the two lineages. Almost equal frequencies of both lineages occurred at centrally located sample locations, with evidence of reproductive isolation between the lineages. A demographic analysis showed that the two lineages diverged and experienced sudden expansion prior to the last glacial maximum, which affected the observed pattern of genetic structure. The spatial distribution, demographic history and degree of genetic distinctiveness found from the genetic analysis, despite the high potential for dispersal in S. mystinus, suggest both lineages diverged in allopatry.     

Molecular phylogeography of Troglophilus cave crickets (Orthoptera,Rhaphidophoridae): A combination of vicariance and dispersal drove diversification in the East Mediterranean region

In this study, we investigated the molecular phylogenetic divergence and historical biogeography of cave crickets belonging to the genus Troglophilus (Orthoptera, Rhaphidophoridae) from caves in eastern Mediterranean and Anatolia regions. Three mitochondrial DNA genes (COI, 12S rDNA, and 16S rDNA) and two nuclear ones (18S rDNA and 28S rDNA) were amplified and partially sequenced to reconstruct phylogenetic relationships among most of the known Troglophilus species. Results showed a well‐resolved phylogeny with three main clades representing the Balkan, the Anatolian, and the Cycladian–Cretan lineages. Based on Bayesian analyses, we applied a relaxed molecular clock model to estimate the divergence times between these three lineages. Dating estimates indicate that radiation of the ingroup might have been triggered by the opening of the Mid‐Aegean trench, while the uplift of the Anatolian Plateau in Turkey and the changes of relief, emergence, and disappearance of orographic and hydrographical barriers in the Balkan Peninsula are potential paleogeographic events responsible for the initial diversification of the genus Troglophilus. A possible biogeographic scenario, reconstructed using S‐DIVA with RASP software, suggested that the current distribution of Troglophilus species can be explained by a combination of both dispersal and vicariance events that occurred in particular in the ancestral populations. The radiation of Troglophilus species likely started from the Aegean and proceeded eastward to Anatolia and westward to the Balkan region. Results are additionally compared to those available for Dolichopoda, the only other representative genus of Rhaphidophoridae present in the Mediterranean area.