In contrast to the Western Palearctic and Nearctic biogeographic regions, the phylogeography of Eastern-Palearctic terrestrial vertebrates has received relatively little attention. In East Asia, tectonic events, along with Pleistocene climatic conditions, likely affected species distribution and diversity, especially through their impact on sea levels and the consequent opening and closing of land-bridges between Eurasia and the Japanese Archipelago. To better understand these effects, we sequenced mitochondrial and nuclear markers to determine phylogeographic patterns in East-Asian tree frogs, with a particular focus on the widespread H. japonica.
SUMMARY Molecular phylogeography has revolutionised our ability to infer past biogeographic events from cross-sectional data on current parasite populations. In ecological parasitology, this approach has been used to address fundamental questions concerning host-parasite co-evolution and geographic patterns of spread, and has raised many technical issues and problems of interpretation. For applied parasitologists, the added complexity inherent in adding population genetic structure to perceived parasite distributions can sometimes seem to cloud rather than clarify approaches to control. In this paper, we use case studies firstly to illustrate the potential extent of cryptic diversity in parasite and parasitoid populations, secondly to consider how anthropogenic influences including movement of domestic animals affect the geographic distribution and host associations of parasite genotypes, and thirdly to explore the applied relevance of these processes to parasites of socio-economic importance. The contribution of phylogeographic approaches to deeper understanding of parasite biology in these cases is assessed. Thus, molecular data on the emerging parasites Angiostrongylus vasorum in dogs and wild canids, and the myiasis-causing flies Lucilia spp. in sheep and Cochliomyia hominovorax in humans, lead to clear implications for control efforts to limit global spread. Broader applications of molecular phylogeography to understanding parasite distributions in an era of rapid global change are also discussed.
The genus Rivulus is currently comprised of two species, R. cylindraceus and R. insulaepinorum, which are endemic to Cuba. However, the taxonomic status of the latter species remains dubious because of the poor quality of the original description. In addition, a recent barcoding survey suggests that the two species may be conspecific. The aim of this study was to test the hypothesis that the two species represent a single evolutionary clade. To delimit the species and their evolutionary history, we used a combination of molecular phylogenetic analyses, with both mitochondrial and nuclear sequences, tests of phylogeographic hypotheses, combined with morphological measurements and information on known dispersal barriers and species distribution. None of the data sets support R. insulaepinorum and R. cylindraceus as separate taxa. However, a new species, restricted to the northwestern part of the main island, was identified by phylogenetic analyses, body colour pattern and geographical distribution. The evolutionary distance between the two lineages (cytb, d = 15%; CAM-4, d = 2.5%) indicates a long period of divergence. Phylogeographic analyses shed light on the dispersal history of R. cylindraceus, which probably originated on the Isla de la Juventud. They also suggest that each lineage had contrasting histories; Rivulus sp. is restricted to a relatively small geographic area whereas R. cylindraceus has dispersed considerably and more than once from its centre of origin, probably facilitated by sea level fluctuations. These results strengthen previous findings, i.e. that the diversity of Cuban freshwater fishes is far from well-known and deserves more in-depth studies, and that vicariance and dispersal events have resulted in a complex biogeographical landscape which has had a significant impact on the freshwater fishes of the Caribbean islands.
Delineating barriers to connectivity is important in marine reserve design as they describe the strength and number of connections among a reserve’s constituent parts, and ultimately help characterize the resilience of the system to perturbations at each node. Here we demonstrate the utility of multi-taxa phylogeography in the design of a system of marine protected areas within Fiji. Gathering mtDNA control region data from five species of coral reef fish in five genera and two families, we find a range of population structure patterns, from those experiencing little (Chrysiptera talboti, Halichoeres hortulanus, and Pomacentrus maafu), to moderate (Amphiprion barberi, Φ(st) = 0.14 and Amblyglyphidodon orbicularis Φ(st) = 0.05) barriers to dispersal. Furthermore estimates of gene flow over ecological time scales suggest species-specific, asymmetric migration among the regions within Fiji. The diversity among species-specific results underscores the limitations of generalizing from single-taxon studies, including the inability to differentiate between a species-specific result and a replication of concordant phylogeographic patterns, and suggests that greater taxonomic coverage results in greater resolution of community dynamics within Fiji. Our results indicate that the Fijian reefs should not be managed as a single unit, and that closely related species can express dramatically different levels of population connectivity.
In recent years, an increasing number of studies incorporated biogeography with phylogenetic analyses to reveal the origin and evolutionary history of specific floras. In this study, we constructed the mega-phylogeny of the floras of three representative regions across Yunnan, southwestern China. We analyzed the phylogenetic structure and beta diversity based on the presence/absence of species (genus or family) data to investigate the phylogenetic patterns of regional floras. We found conspicuous divergence at the genus and species level in the pattern of phylogenetic structures, which most likely related to historical biogeography. The flora of southern Yunnan was shaped by the strike-slip extrusion of Indochina and the regional climatic stability, while the flora of northwestern Yunnan was shaped by the uplift of the Himalaya-Tibetan Plateau and the oscillations of the glacial-interglacial periods. The flora of central Yunnan had nearly equal proportions of the northern and southern floras that may be derived from a common Tertiary tropical or subtropical flora. Geological events fit well with the floristic and phylogenetic patterns across Yunnan. This study highlighted the importance of linking phylogenetic analyses to biogeographic interpretations to improve our understanding of the origin, evolution and divergence of regional floras.
Exon-capture studies have typically been restricted to relatively shallow phylogenetic scales due primarily to hybridisation constraints. Here, we present an exon-capture system for an entire class of marine invertebrates, the Ophiuroidea, built upon a phylogenetically diverse transcriptome foundation. The system captures ~90% of the 1552 exon target, across all major lineages of the quarter-billion year old extant crown group. Key features of our system are: 1) basing the target on an alignment of orthologous genes determined from 52 transcriptomes spanning the phylogenetic diversity and trimmed to remove anything difficult to capture, map or align, 2) use of multiple artificial representatives based on ancestral state reconstructions rather than exemplars to improve capture and mapping of the target, 3) mapping reads to a multi-reference alignment, and 4) using patterns of site polymorphism to distinguish among paralogy, polyploidy, allelic differences and sample contamination. The resulting data gives a well-resolved tree (currently standing at 417 samples, 275,352 sites, 91% data-complete) that will transform our understanding of ophiuroid evolution and biogeography.
Most phylogenies are typically represented as purely bifurcating. However, as genomic data has become more common in phylogenetic studies, it is not unusual to find reticulation among terminal lineages or among internal nodes (deep time reticulation; DTR). In these situations, gene flow must have happened in the same or adjacent geographic areas for these DTRs to have occurred and therefore biogeographic reconstruction should provide similar area estimates for parental nodes, provided extinction or dispersal has not eroded these patterns. We examine the phylogeny of the widely distributed New World kingsnakes (Lampropeltis), determine if DTR is present in this group, and estimate the ancestral area for reticulation. Importantly, we develop a new method that uses coalescent simulations in a machine learning framework to show conclusively that this phylogeny is best represented as reticulating at deeper time. Using joint probabilities of ancestral area reconstructions on the bifurcating parental lineages from the reticulating node, we show that this reticulation likely occurred in northwestern Mexico/southwestern US and subsequently led to the diversification of the Mexican kingsnakes. This region has been previously identified as an area important for understanding speciation and secondary contact with gene flow in snakes and other squamates. This research shows that phylogenetic reticulation is common, even in well-studied groups, and that the geographic scope of ancient hybridization is recoverable.
Reliably rooted phylogenetic trees play irreplaceable roles in clarifying diversification in the patterns of species and populations. However, such trees are often unavailable in phylogeographic studies, particularly when the focus is on rapidly expanded populations that exhibit star-like trees. A fundamental bottleneck is known as the random rooting effect, where a distant outgroup tends to root an unrooted tree “randomly.” We investigated whether parallel mitochondrial genome (mitogenome) sequencing alleviates this effect in phylogeography using a case study on the Sea of Japan lineage of the intertidal gobyChaenogobius annularis Eighty-threeC. annularisindividuals were collected and their mitogenomes were determined by high-throughput and low-cost parallel sequencing. Phylogenetic analysis of these mitogenome sequences was conducted to root the Sea of Japan lineage, which has a star-like phylogeny and had not been reliably rooted. The topologies of the bootstrap trees were investigated to determine whether the use of mitogenomes alleviated the random rooting effect. The mitogenome data successfully rooted the Sea of Japan lineage by alleviating the effect, which hindered phylogenetic analysis that used specific gene sequences. The reliable rooting of the lineage led to the discovery of a novel, northern lineage that expanded during an interglacial period with high bootstrap support. Furthermore, the finding of this lineage suggested the existence of additional glacial refugia and provided a new recent calibration point that revised the divergence time estimation between the Sea of Japan and Pacific Ocean lineages. This study illustrates the effectiveness of parallel mitogenome sequencing for solving the random rooting problem in phylogeographic studies.
The Osprey (Pandion haliaetus) is one of only six bird species with an almost world-wide distribution. We aimed at clarifying its phylogeographic structure and elucidating its taxonomic status (as it is currently separated into four subspecies). We tested six biogeographical scenarios to explain how the species' distribution and differentiation took place in the past and how such a specialized raptor was able to colonize most of the globe.