Transoceanic Dispersal Research Articles

From mainland to islands: colonization history in the tree frog Kurixalus (Anura: Rhacophoridae).

The origin and colonization history of Kurixalus, a genus of small arboreal tree frogs breeding exclusively in shallow swamps, is under disputed. On the basis of comprehensive sampling program, the evolutionary history of Kurixalus is investigated based on 3 mitochondrial genes. Our results indicate that the genus Kurixalus originated in the Asian mainland and subsequently arrived at its current distribution in Borneo, Taiwan, Ryukyu, and Hainan islands by a series of dispersal events. Moreover, the colonization of Taiwan from mainland Asia has occurred 2 times. The initial colonization of Taiwan occurred at 3.46–8.68 Mya (95% highest posterior density), which rejects the hypothesis that Kurixalus probably originated from Taiwan during the early Oligocene and favors the model of Neogene-origin rather than the model of Quaternary-origin for Taiwanese Kurixalus. Kurixalus eiffingeri has dispersed from Taiwan to the Ryukyus once or 2 times pending more data. Both transoceanic dispersal and landbridge dispersal have played a role in the colonization process; the former resulted in the colonization of Taiwan and the Ryukyus and the latter led to the colonization of Borneo and Hainan.

A total-evidence approach resolves phylogenetic placement of ‘Cafius’ gigas,a unique recently extinct rove beetle from Lord Howe Island

AbstractCafius gigas Lea, 1929 (Coleoptera: Staphylinidae) was a large rove beetle endemic to Lord Howe Island (LHI) resembling Cafius and the LHI flightless endemic Hesperus dolichoderes (Lea, 1925). Like several other LHI endemics, C. gigas became extinct due to human-introduced rats. It is a legacy species valuable for understanding the LHI biota in terms of evolutionary biology and historical biogeography. Whether C. gigas was a member of Cafius Curtis, 1829, restricted to oceanic shores and prone to trans-oceanic dispersal, or related to H. dolichoderes, would have different implications. We subjected C. gigas to a total-evidence phylogenetic analyses of morphological and molecular data using model-based and parsimony methods. As a result, it is transferred to Hesperus Fauvel, 1874 with the new combination Hesperus gigas (Lea, 1929) comb. nov. Our analysis indicates that the montane leaf litter inhabitant H. gigas evolved neither in situ nor from a seashore Cafius-ancestor, or from an ancestor shared by two other LHI endemic congeners, Hesperus pacificus Olliff, 1887 and H. dolichoderes. It also suggests that all three Hesperus species that currently occur on LHI could have evolved on various seamounts at various times before reaching LHI.

Phylogenomics and biogeography of the world's thrushes (Aves, Turdus): new evidence for a more parsimonious evolutionary history.

To elucidate the relationships and spatial range evolution across the world of the bird genus Turdus (Aves), we produced a large genomic dataset comprising ca 2 million nucleotides for ca 100 samples representing 53 species, including over 2000 loci. We estimated time-calibrated maximum-likelihood and multispecies coalescent phylogenies and carried out biogeographic analyses. Our results indicate that there have been considerably fewer trans-oceanic dispersals within the genus Turdus than previously suggested, such that the Palaearctic clade did not originate in America and the African clade was not involved in the colonization of the Americas. Instead, our findings suggest that dispersal from the Western Palaearctic via the Antilles to the Neotropics might have occurred in a single event, giving rise to the rich Neotropical diversity of Turdus observed today, with no reverse dispersals to the Palaearctic or Africa. Our large multilocus dataset, combined with dense species-level sampling and analysed under probabilistic methods, brings important insights into historical biogeography and systematics, even in a scenario of fast and spatially complex diversification.

First report of Osedax in the Indian Ocean indicative of trans-oceanic dispersal through the Southern Ocean

Three specimens of the bone-eating worms, Osedax rubiplumus Rouse, Goffredi & Vrijenhoek, 2004, were collected from pig bones deployed in the periphery of Longqi vent field on the Southwest Indian Ridge (SWIR). Osedax rubiplumus was previously only reported in both the eastern and western North Pacific and Antarctic oceans. Our finding extends its range to the Indian Ocean, representing a much wider distribution of O. rubiplumus than previously expected. Moreover, all individuals of O. rubiplumus from the SWIR form a single haplotype with the highest divergence from the Pacific ones.

How ‘Gondwanan’ is Riethia? Molecular phylogenetics elucidates the mode and tempo of diversification in Austro-Pacific Chironominae (Diptera)

Riethia Kieffer, a genus of the non-biting midge subfamily Chironominae (Diptera: Chironomidae) is distributed in Australia, New Zealand, New Caledonia and South America. This austral distribution could be due to earth history (vicariance) or from Southern Hemisphere dispersal(s). We obtained samples from each area, most intensively from throughout Australia. We included putative sister genus Pseudochironomus Malloch, many genera from tribe Tanytarsini, enigmatic taxa in Chironomini and conventional outgroups from other subfamilies. We assembled a multilocus molecular dataset for four genetic regions from 107 individuals to reconstruct the first dated molecular phylogeny for the group. Four terminal clusters corresponded to unreared (thus unassociated) larvae. Monophyly was supported for ‘core’ Riethia, Pseudochironomus, putative tribe Pseudochironomini, tribe Tanytarsini (including enigmatic Nandeva Wiedenbrug, Reiss & Fittkau) and subfamily Chironominae. All species are monophyletic except for R. cinctipes Freeman, which includes R. neocaledonica Cranston. Riethia zeylandica Freeman, previously thought to be widespread in eastern Australia, now is a New Zealand endemic with Australian specimens allocated now to several regionally restricted species. The origin of Riethia was at 60.6 Ma (‘core’) or 52.1 Ma depending on the relationship of two South American species. Both dates are before the break-up of South America and Australia. Diversification within crown group Riethia started before the Cretaceous–Paleogene boundary, with subsequent separation at 52 Ma of an Australian ‘clade I’ from its sister ‘clade II’, which comprises Australian, New Zealand and New Caledonian species. Inferred dates for species origins of New Caledonia and New Zealand taxa imply transoceanic dispersals from eastern Australia. Western Australian species diverged during the mid to late Miocene from their eastern Australian sister taxa. This correlates with the onset of drying of Australia and the separation of mesic east from west by the formation of an arid proto-Nullarbor. Taken together, the inferred tempo of diversification in the group included both older ages reflecting earth history, yet with suggested recent intra-Pacific separations due to transoceanic dispersals.

Molecular phylogeny and biogeography of the temperate Gondwanan family Triaenonychidae (Opiliones : Laniatores) reveals pre-Gondwanan regionalisation, common vicariance, and rare dispersal

Triaenonychidae Sørensen in L. Koch, 1886 is a large family of Opiliones with ~480 described species broadly distributed across temperate forests in the Southern Hemisphere. However, it remains poorly understood taxonomically, as no comprehensive phylogenetic work has ever been undertaken. In this study we capitalise on samples largely collected by us during the last two decades and use Sanger DNA-sequencing techniques to produce a large phylogenetic tree with 300 triaenonychid terminals representing nearly 50% of triaenonychid genera and including representatives from all the major geographic areas from which they are known. Phylogenetic analyses using maximum likelihood and Bayesian inference methods recover the family as diphyletic, placing Lomanella Pocock, 1903 as the sister group to the New Zealand endemic family Synthetonychiidae Forster, 1954. With the exception of the Laurasian representatives of the family, all landmasses contain non-monophyletic assemblages of taxa. To determine whether this non-monophyly was the result of Gondwanan vicariance, ancient cladogenesis due to habitat regionalisation, or more recent over-water dispersal, we inferred divergence times. We found that most divergence times between landmasses predate Gondwanan breakup, though there has been at least one instance of transoceanic dispersal – to New Caledonia. In all, we identify multiple places in the phylogeny where taxonomic revision is needed, and transfer Lomanella outside of Triaenonychidae in order to maintain monophyly of the family.

Analyses of Plastome Sequences Improve Phylogenetic Resolution and Provide New Insight Into the Evolutionary History of Asian Sonerileae/Dissochaeteae.

Sonerileae/Dissochaeteae (Melastomataceae) comprises ca. 50 genera, two thirds of which occur in Southeast Asia. Phylogenetic relationships within this clade remain largely unclear, which hampers our understanding of its origin, evolution, and biogeography. Here, we explored the use of chloroplast genomes in phylogenetic reconstruction of Sonerileae/Dissochaeteae, by sampling 138 species and 23 genera in this clade. A total of 151 complete plastid genomes were assembled for this study. Plastid genomic data provided better support for the backbone of the Sonerileae/Dissochaeteae phylogeny, and also for relationships among most closely related species, but failed to resolve the short internodes likely resulted from rapid radiation. Trees inferred from plastid genome and nrITS sequences were largely congruent regarding the major lineages of Sonerileae/Dissochaeteae. The present analyses recovered 15 major lineages well recognized in both nrITS and plastid phylogeny. Molecular dating and biogeographical analyses indicated a South American origin for Sonerileae/Dissochaeteae during late Eocene (stem age: 34.78 Mya). Two dispersal events from South America to the Old World were detected in late Eocene (33.96 Mya) and Mid Oligocene (28.33 Mya) respectively. The core Asian clade began to diversify around early Miocene in Indo-Burma and dispersed subsequently to Malesia and Sino-Japanese regions, possibly promoted by global temperature changes and East Asian monsoon activity. Our analyses supported previous hypothesis that Medinilla reached Madagascar by transoceanic dispersal in Miocene. In addition, generic limits of some genera concerned were discussed.

The age and diversification of metacrangonyctid subterranean amphipod crustaceans revisited

The Metacrangonyctidae are a small family of amphipod crustaceans of marine origin found only in subterranean continental waters. They display a broad but punctuated distribution between the Caribbean and the Arabian Peninsula, with major disjunctions either due to vicariance by plate tectonics or to occurrence of recent episodes of long-distance transoceanic dispersal. We re-examine the phylogeny of the family and the time frame for its diversification using mitochondrial genomes in the light of two key taxa recently discovered, from Oman (Arabian Peninsula) and the Rif area of Morocco, respectively. We also use a novel fossil calibration scheme of the mitogenome phylogeny. Results of previous analyses based on palaeogeographic calibrations are not contradicted by the new approach, with vicariance by plate tectonics remaining as the main explanatory factor for the amphi-Atlantic distribution displayed by this ancient group of subterranean amphipods.

Worldwide long‐distance dispersal favored by epizoochorous traits in the biogeographic history of Omphalodeae (Boraginaceae)

AbstractBiogeographic dispersal is supported by numerous phylogenetic results. In particular, transoceanic dispersal, rather than vicariance, is suggested for some plant lineages despite current long distances between America and Europe. However, few studies on the biogeographic history of plants have also studied the role of diaspore syndromes in long‐distance dispersal (LDD). Species of the tribe Omphalodeae (Boraginaceae) offer a suitable study system because the species have a wide variety of diaspore traits related to LDD and different lineages conform to patched worldwide distributions on three distant continents (Europe, America and New Zealand). Our aim is to reconstruct the biogeographical history of the Omphalodeae and to investigate the role of diaspore traits favoring LDD and current geographic distributions. To this end, a time‐calibrated phylogeny with 29 of 32 species described for Omphalodeae was reconstructed using biogeographical analyses (BioGeoBEARS, Lagrange) and models (DEC and DIVA) under different scenarios of land connectivity. Character‐state reconstruction (SIMMAP) and diversification rate estimations of the main lineages were also performed. The main result is that epizoochorous traits have been the ancestral state of LDD syndromes in most clades. An early diversification age of the tribe is inferred in the Western Mediterranean during late Oligocene. Colonization of the New World by Omphalodeae, followed by fast lineage differentiation, took place sometime in the Oligocene‐Miocene boundary, as already inferred for other angiosperm genera. In contrast, colonization of remote islands (New Zealand, Juan Fernández) occurred considerably later in the Miocene‐Pliocene boundary.

Habitat preference modulates trans-oceanic dispersal in a terrestrial vertebrate.

The importance of long-distance dispersal (LDD) in shaping geographical distributions has been debated since the nineteenth century. In terrestrial vertebrates, LDD events across large water bodies are considered highly improbable, but organismal traits affecting dispersal capacity are generally not taken into account. Here, we focus on a recent lizard radiation and combine a summary-coalescent species tree based on 1225 exons with a probabilistic model that links dispersal capacity to an evolving trait, to investigate whether ecological specialization has influenced the probability of trans-oceanic dispersal. Cryptoblepharus species that occur in coastal habitats have on average dispersed 13 to 14 times more frequently than non-coastal species and coastal specialization has, therefore, led to an extraordinarily widespread distribution that includes multiple continents and distant island archipelagoes. Furthermore, their presence across the Pacific substantially predates the age of human colonization and we can explicitly reject the possibility that these patterns are solely shaped by human-mediated dispersal. Overall, by combining new analytical methods with a comprehensive phylogenomic dataset, we use a quantitative framework to show how coastal specialization can influence dispersal capacity and eventually shape geographical distributions at a macroevolutionary scale.

Genetic data reveals a complex history of multiple admixture events in presently allopatric wild gingers (Asarum spp.) showing intertaxonomic clinal variation in calyx lobe length

Clinal variation is a major pattern of observed phenotypic diversity and identifying underlying demographic processes is a necessary step to understand the establishment of clinal variation. The wild ginger series Sakawanum (genus Asarum) comprises four taxa, which exhibit intertaxonomic clinal variation in calyx lobe length across two continental islands isolated by a sea strait. To test alternative hypotheses of the evolutionary history and to determine the implications for the formation of clinal variation, we conducted approximate Bayesian computation (ABC) analysis and ecological niche modeling (ENM). ABC analysis indicated that the scenario assuming multiple admixture events was strongly supported. This scenario assumed two admixture events occurred between morphologically distinct taxa, likely leading to the generation of intermediate taxa. One of the admixture events was estimated to have occurred during the last glacial maximum (LGM), during which the taxa were estimated to have formed a common refugia in southern areas by ENM analysis. Although four taxa are currently distributed allopatrically on different islands and trans-oceanic dispersal appears unlikely, the formation of a land bridge and the geographic range shift to refugia would have allowed secondary contact between previously isolated taxa. This study suggests that clinal variation can be shaped by demographic history including multiple admixtures due to climatic oscillations.

Calibrating the tree of vipers under the fossilized birth-death model

Scaling evolutionary trees to time is essential for understanding the origins of clades. Recently developed methods allow including the entire fossil record known for the group of interest and eliminated the need for specifying prior distributions for node ages. Here we apply the fossilized birth-death (FBD) approach to reconstruct the diversification timeline of the viperines (subfamily Viperinae). Viperinae are an Old World snake subfamily comprising 102 species from 13 genera. The fossil record of vipers is fairly rich and well assignable to clades due to the unique vertebral and fang morphology. We use an unprecedented sampling of 83 modern species and 13 genetic markers in combination with 197 fossils representing 28 extinct taxa to reconstruct a time-calibrated phylogeny of the Viperinae. Our results suggest a late Eocene-early Oligocene origin with several diversification events following soon after the group’s establishment. The age estimates inferred with the FBD model correspond to those from previous studies that were based on node dating but FBD provides notably narrower credible intervals around the node ages. Viperines comprise two African and an Eurasian clade, but the ancestral origin of the subfamily is ambiguous. The most parsimonious scenarios require two transoceanic dispersals over the Tethys Sea during the Oligocene.

Leafflower–leafflower moth mutualism in the Neotropics: Successful transoceanic dispersal from the Old World to the New World by actively-pollinating leafflower moths

In the Old World tropics, several hundred species of leafflowers (Phyllanthus sensu lato; Phyllanthaceae) are engaged in obligate mutualisms with species-specific leafflower moths (Epicephala; Gracillariidae) whose adults actively pollinate flowers and larvae consume the resulting seeds. Considerable diversity of Phyllanthus also exists in the New World, but whether any New World Phyllanthus is pollinated by Epicephala is unknown. We studied the pollination biology of four woody Phyllanthus species occurring in Peru over a period of four years, and found that each species is associated with a species-specific, seed-eating Epicephala moth, here described as new species. Another Epicephala species found associated with herbaceous Phyllanthus is also described. This is the first description of Epicephala from the New World. Field-collected female moths of the four Epicephala species associated with woody Phyllanthus all carried pollen on the proboscises, and active pollination behavior was observed in at least two species. Thus, Epicephala moths also pollinate New World Phyllanthus. However, not all of these Epicephala species may be mutualistic with their hosts, because we occasionally observed females laying eggs in developing fruits without pollinating. Also, the flowers of some Phyllanthus species were visited by pollen-bearing thrips or gall midges, which potentially acted as co-pollinators or primary pollinators. Phylogenetic analysis showed that the New World Epicephala associated with woody Phyllanthus are nested within lineages of Old World active pollinators. Thus, actively-pollinating Epicephala moths, which originated in the Old World, successfully colonized the New World probably across the Pacific and established mutualisms with resident Phyllanthus species, although whether any of the relationships are obligate requires further study. There is likely a major radiation of Epicephala still to be found in the New World.

Seed size evolution and biogeography of Plukenetia (Euphorbiaceae), a pantropical genus with traditionally cultivated oilseed species

BackgroundPlukenetia is a small pantropical genus of lianas and vines with variably sized edible oil-rich seeds that presents an ideal system to investigate neotropical and pantropical diversification patterns and seed size evolution. We assessed the biogeography and seed evolution of Plukenetia through phylogenetic analyses of a 5069 character molecular dataset comprising five nuclear and two plastid markers for 86 terminals in subtribe Plukenetiinae (representing 20 of ~ 23 Plukenetia species). Two nuclear genes, KEA1 and TEB, were used for phylogenetic reconstruction for the first time. Our goals were: (1) produce a robust, time-dependent evolutionary framework for Plukenetia using BEAST; (2) reconstruct its biogeographical history with ancestral range estimation in BioGeoBEARS; (3) define seed size categories; (4) identify patterns of seed size evolution using ancestral state estimation; and (5) conduct regression analyses with putative drivers of seed size using the threshold model.ResultsPlukenetia was resolved into two major groups, which we refer to as the pinnately- and palmately-veined clades. Our analyses suggest Plukenetia originated in the Amazon or Atlantic Forest of Brazil during the Oligocene (28.7 Mya) and migrated/dispersed between those regions and Central America/Mexico throughout the Miocene. Trans-oceanic dispersals explain the pantropical distribution of Plukenetia, including from the Amazon to Africa in the Early Miocene (17.4 Mya), followed by Africa to Madagascar and Africa to Southeast Asia in the Late Miocene (9.4 Mya) and Pliocene (4.5 Mya), respectively. We infer a single origin of large seeds in the ancestor of Plukenetia. Seed size fits a Brownian motion model of trait evolution and is moderately to strongly associated with plant size, fruit type/dispersal syndrome, and seedling ecology. Biome shifts were not drivers of seed size, although there was a weak association with a transition to fire prone semi-arid savannas.ConclusionsThe major relationships among the species of Plukenetia are now well-resolved. Our biogeographical analyses support growing evidence that many pantropical distributions developed by periodic trans-oceanic dispersals throughout the Miocene and Pliocene. Selection on a combination of traits contributed to seed size variation, while movement between forest edge/light gap and canopy niches likely contributed to the seed size extremes in Plukenetia.

Historical biogeography of the termite clade Rhinotermitinae (Blattodea: Isoptera)

Termites are the principal decomposers in tropical and subtropical ecosystems around the world. Time-calibrated molecular phylogenies show that some lineages of Neoisoptera diversified during the Oligocene and Miocene, and acquired their pantropical distribution through transoceanic dispersal events, probably by rafting in wood. In this paper, we intend to resolve the historical biogeography of one of the earliest branching lineages of Neoisoptera, the Rhinotermitinae. We used the mitochondrial genomes of 27 species of Rhinotermitinae to build two robust time-calibrated phylogenetic trees that we used to reconstruct the ancestral distribution of the group. Our analyses support the monophyly of Rhinotermitinae and all genera of Rhinotermitinae. Our molecular clock trees provided time estimations that diverged by up to 15.6 million years depending on whether or not 3rd codon positions were included. Rhinotermitinae arose 50.4–64.6 Ma (41.7–74.5 Ma 95% HPD). We detected four disjunctions among biogeographic realms, the earliest of which occurred 41.0–56.6 Ma (33.0–65.8 Ma 95% HPD), and the latest of which occurred 20.3–34.2 Ma (15.9–40.4 Ma 95% HPD). These results show that the Rhinotermitinae acquired their distribution through a combination of transoceanic dispersals and dispersals across land bridges.

Insights into the Evolution of the New World Diploid Cottons (Gossypium, Subgenus Houzingenia) Based on Genome Sequencing.

We employed phylogenomic methods to study molecular evolutionary processes and phylogeny in the geographically widely dispersed New World diploid cottons (Gossypium, subg. Houzingenia). Whole genome resequencing data (average of 33× genomic coverage) were generated to reassess the phylogenetic history of the subgenus and provide a temporal framework for its diversification. Phylogenetic analyses indicate that the subgenus likely originated following transoceanic dispersal from Africa about 6.6 Ma, but that nearly all of the biodiversity evolved following rapid diversification in the mid-Pleistocene (0.5–2.0 Ma), with multiple long-distance dispersals required to account for range expansion to Arizona, the Galapagos Islands, and Peru. Comparative analyses of cpDNAversus nuclear data indicate that this history was accompanied by several clear cases of interspecific introgression. Repetitive DNAs contribute roughly half of the total 880 Mb genome, but most transposable element families are relatively old and stable among species. In the genic fraction, pairwise synonymous mutation rates average 1% per Myr, with nonsynonymous changes being about seven times less frequent. Over 1.1 million indels were detected and phylogenetically polarized, revealing a 2-fold bias toward deletions over small insertions. We suggest that this genome down-sizing bias counteracts genome size growth by TE amplification and insertions, and helps explain the relatively small genomes that are restricted to this subgenus. Compared with the rate of nucleotide substitution, the rate of indel occurrence is much lower averaging about 17 nucleotide substitutions per indel event.

Turnover of southern cypresses in the post-Gondwanan world: extinction, transoceanic dispersal, adaptation and rediversification.

Summary Cupressaceae subfamily Callitroideae has been an important exemplar for vicariance biogeography, but its history is more than just disjunctions resulting from continental drift. We combine fossil and molecular data to better assess its extinction and, sometimes, rediversification after past global change.Key fossils were reassessed and their phylogenetic placement for calibration was determined using trait mapping and Bayes Factors. Five vicariance hypotheses were tested by comparing molecular divergence times with the timing of tectonic rifting. The role of adaptation to fire (serotiny) in its spread across a drying Australia was tested for Callitris.Our findings suggest that three transoceanic disjunctions within the Callitroideae probably arose from long‐distance dispersal. A signature of extinction, centred on the end‐Eocene global climatic chilling and drying, is evident in lineages‐through‐time plots and in the fossil record. Callitris, the most diverse extant callitroid genus, suffered extinctions but surviving lineages adapted and re‐radiated into dry, fire‐prone biomes that expanded in the Neogene. Serotiny, a key adaptation to fire, likely evolved in Callitris coincident with the biome shift.Both extinction and adaptive shifts have probably played major roles in this chronicle of turnover and renewal, but better understanding of biogeographical history requires improved taxonomy of fossils.

Geographical and temporal origins of terrestrial vertebrates endemic to Taiwan

AbstractAimPhylogeographical studies of Taiwan have advanced our knowledge of the origins of its fauna, but the discrepancies raise issues related to the interpretation of single‐taxon studies. Here, we provide a synthesis of the biogeographical histories of multiple terrestrial vertebrates endemic to Taiwan and infer the colonization processes within the context of geological and climatic events.LocationTaiwan and neighbouring land masses.TaxonTerrestrial vertebrates.MethodsWe conducted a meta‐analysis of 28 phylogenetic studies of 33 endemic Taiwanese terrestrial vertebrates to summarize the insights into their source regions and divergence times. We used dispersal–extinction–cladogenesis models to reconstruct the ancestral ranges of 54 endemic species based on a recently published time‐calibrated phylogenetic tree. By constructing a frequency histogram that quantified the number and timing of divergence events within 1 Myr bins, we inferred the spatiotemporal colonization patterns of endemic Taiwanese species.ResultsThe results from 28 phylogenetic studies revealed that South China is the main source region of endemic Taiwanese species. However, based on a more comprehensive time tree, the ancestral area reconstruction analyses indicated that endemic species are predominately of Eastern Himalayan origin. Both datasets highlighted a temporal pattern that the majority of colonization events of terrestrial vertebrates endemic to Taiwan occurred from the early Pliocene (c. 5 Ma) onwards, and these events were temporally congruent with the geological estimates of the emergence of Taiwan Island.Main conclusionsTerrestrial vertebrates endemic to Taiwan reached the island over the last 5 Myr from a variety of zoogeographical regions. In contrast to the traditional notion, the Eastern Himalayas is the most important source region of endemic Taiwanese species, followed by South China and Indochina. In addition to the land bridge, transoceanic dispersal provided another potential mode for species to colonize Taiwan.

Revised phylogeny and historical biogeography of the cosmopolitan aquatic plant genus Typha (Typhaceae)

Typha is a cosmopolitan aquatic plant genus that includes species with widespread distributions. It is a relatively ancient genus with an abundant fossil record dating back to the Paleogene. However, the details of its biogeographic history have remained unclear until now. In this study, we present a revised molecular phylogeny using sequences of seven chloroplast DNA markers from nine species sampled from various regions in order to infer the biogeographic history of the genus. Two clades were recovered with robust support. Typha minima and T. elephantina comprised one clade, and the other clade included the remaining seven species, which represented a polytomy of four robustly supported subclades. Two widespread species, T. angustifolia and T. domingensis, were revealed to be paraphyletic, indicating the need for taxonomic revision. Divergence time estimation suggested that Typha had a mid-Eocene crown origin, and its diversification occurred in the Middle and Late Miocene. Ancestral area reconstruction showed that Typha possibly originated from eastern Eurasia. Both dispersal via the Beringian Land Bridge and recent transoceanic dispersal may have influenced the intercontinental distribution of Typha species.

Phylogeny, biogeography and diversification patterns of side-necked turtles (Testudines: Pleurodira).

Pleurodires or side-necked turtles are today restricted to freshwater environments of South America, Africa–Madagascar and Australia, but in the past they were distributed much more broadly, being found also on Eurasia, India and North America, and marine environments. Two hypotheses were proposed to explain this distribution; in the first, vicariance would have shaped the current geographical distribution and, in the second, extinctions constrained a previously widespread distribution. Here, we aim to reconstruct pleurodiran biogeographic history and diversification patterns based on a new phylogenetic hypothesis recovered from the analysis of the largest morphological dataset yet compiled for the lineage, testing which biogeographical process prevailed during its evolutionary history. The resulting topology generally agrees with previous hypotheses of the group and shows that most diversification shifts were related to the exploration of new niches, e.g. littoral or marine radiations. In addition, as other turtles, pleurodires do not seem to have been much affected by either the Cretaceous–Palaeogene or the Eocene–Oligocene mass extinctions. The biogeographic analyses highlight the predominance of both anagenetic and cladogenetic dispersal events and support the importance of transoceanic dispersals as a more common driver of area changes than previously thought, agreeing with previous studies with other non-turtle lineages.