Biogeographic Events Research Articles

Deep‐sea squat lobster biogeography (Munidopsidae: Leiogalathea) unveils Tethyan vicariance and evolutionary patterns shared by shallow‐water relatives

AbstractThe ecology, abundance and diversity of galatheoid squat lobsters make them an ideal group to study deep‐sea diversification processes. Here, we reconstructed the evolutionary and biogeographic history of Leiogalathea, a genus of circum‐tropical deep‐sea squat lobsters, in order to compare patterns and processes that have affected shallow‐water and deep‐sea squat lobster species. We first built a multilocus phylogeny and a calibrated species tree with a relaxed clock using StarBEAST2 to reconstruct evolutionary relationships and divergence times among Leiogalathea species. We used BioGeoBEARS and a DEC model, implemented in RevBayes, to reconstruct ancestral distribution ranges and the biogeographic history of the genus. Our results showed that Leiogalathea is monophyletic and comprises four main lineages; morphological homogeneity is common within and between clades, except in one; the reconstructed ancestral range of the genus is in the Atlantic and Indian oceans (Tethys). They also revealed the divergence of the Atlantic species around 25 million years ago (Ma), intense cladogenesis 15–25 Ma and low levels of speciation over the last 5 million years (Myr). The four Leiogalathea lineages showed similar patterns of speciation: allopatric speciation followed by range expansion and subsequent stasis. Leiogalathea started diversifying during the Oligocene, likely in the Tethyan. The Atlantic lineage then split from its Indo‐Pacific sister group due to vicariance driven by closure of the Tethys Seaway. The Atlantic lineage is less speciose compared with the Indo‐Pacific lineages, with the Tropical Southwestern Pacific being the current centre of diversity. Leiogalathea diversification coincided with cladogenetic peaks in shallow‐water genera, indicating that historical biogeographic events similarly shaped the diversification and distribution of both deep‐sea and shallow‐water squat lobsters.

The combined role of dispersal and niche evolution in the diversification of Neotropical lizards.

Ecological requirements and environmental conditions can influence diversification across temporal and spatial scales. Understanding the role of ecological niche evolution under phylogenetic contexts provides insights on speciation mechanisms and possible responses to future climatic change. Large‐scale phyloclimatic studies on the megadiverse Neotropics, where biomes with contrasting vegetation types occur in narrow contact, are rare. We integrate ecological and biogeographic data with phylogenetic comparative methods, to investigate the relative roles of biogeographic events and niche divergence and conservatism on the diversification of the lizard genus Kentropyx Spix, 1825 (Squamata: Teiidae), distributed in South American rainforests and savannas. Using five molecular markers, we estimated a dated species tree, which recovered three clades coincident with previously proposed species groups diverging during the mid‐Miocene. Biogeography reconstruction indicates a role of successive dispersal events from an ancestral range in the Brazilian Shield and western Amazonia. Ancestral reconstruction of climatic tolerances and niche overlap metrics indicates a trend of conservatism during the diversification of groups from the Amazon Basin and Guiana Shield, and a strong signal of niche divergence in the Brazilian Shield savannas. Our results suggest that climatic‐driven divergence at dynamic forest‐savanna borders might have resulted in adaptation to new environmental niches, promoting habitat shifts and shaping speciation patterns of Neotropical lizards. Dispersal and ecological divergence could have a more important role in Neotropical diversification than previously thought.

Evolutionary history of two cryptic species of northern African jerboas

BackgroundClimatic variation and geologic change both play significant roles in shaping species distributions, thus affecting their evolutionary history. In Sahara-Sahel, climatic oscillations shifted the desert extent during the Pliocene-Pleistocene interval, triggering the diversification of several species. Here, we investigated how these biogeographical and ecological events have shaped patterns of genetic diversity and divergence in African Jerboas, desert specialist rodents. We focused on two sister and cryptic species, Jaculus jaculus and J. hirtipes, where we (1) evaluated their genetic differentiation, (2) reconstructed their evolutionary and demographic history; (3) tested the level of gene flow between them, and (4) assessed their ecological niche divergence.ResultsThe analyses based on 231 individuals sampled throughout North Africa, 8 sequence fragments (one mitochondrial and seven single copy nuclear DNA, including two candidate genes for fur coloration: MC1R and Agouti), 6 microsatellite markers and ecological modelling revealed: (1) two distinct genetic lineages with overlapping distributions, in agreement with their classification as different species, J. jaculus and J. hirtipes, with (2) low levels of gene flow and strong species divergence, (3) high haplotypic diversity without evident geographic structure within species, and (4) a low level of large-scale ecological divergence between the two taxa, suggesting species micro-habitat specialization.ConclusionsOverall, our results suggest a speciation event that occurred during the Pliocene-Pleistocene transition. The contemporary distribution of genetic variation suggests ongoing population expansions. Despite the largely overlapping distributions at a macrogeographic scale, our genetic results suggest that the two species remain reproductively isolated, as only negligible levels of gene flow were observed. The overlapping ecological preferences at a macro-geographic scale and the ecological divergence at the micro-habitat scale suggest that local adaptation may have played a crucial role in the speciation process of these species.

Organellar Genome Variation and Genetic Diversity of Chinese Pyropia yezoensis

Pyropia yezoensis is an economically important marine algae crop that, due to its large economic value, has generated considerable interest in the development of breeding programs to improve its production rates. Here, we sequenced the complete mitochondrial and plastid genomes of the P. yezoensis strain RZ-58 using PacBio RS II sequencing technology. The mitochondrial genome (mtDNA) is 41,692 bp in size with an overall GC content of 32.72%, and the plastid genome (ptDNA) is 191,977 bp with a GC content of 33.09%. The complete mitochondrial and plastid genomes of 53 individuals from 3 geographical populations were then resequenced using NGS technology to characterize their molecular features. When compared, the plastid genomes displayed similar genomic lengths and conserved gene synteny. However, mitochondrial genomes were quite different in length, which was mainly due to the different patterns of intron distributions. Single nucleotide polymorphisms (SNPs) were examined to evaluate the genetic diversity of different geographical populations. High diversity was observed across the whole collection with moderate genetic variation between populations. In total, there were 463 and 366 high-quality SNPs detected in the mtDNA and ptDNA, respectively. The Qingdao wild group has the highest diversity with a mean pi of 0.00348 for mtDNA and 0.000388 for ptDNA, while the Yantai group had the lowest diversity. Cluster based grouping and principal component analysis revealed three subpopulations in the whole collections. However, a genetic break of organellar DNA was observed in populations at sympatric localities, which was inferred as the result of historic biogeographic events. Our findings provide important information to guide the marker-assisted selective breeding of Chinese P. yezoensis in the future.

Nannoplankton-Based Biostratigraphic Subdivisions in the Reference Sections of the Taman Trough and Ciscaucasia

Integrated paleomagnetic and biostratigraphic study of the Neogene sedimentary sequences in the reference sections of the Taman Trough and Ciscaucasia allowed substantially new datings of biotic and biogeographic events in the Middle Miocene to be obtained, suggesting a connection with the world’s oceans in the Lower Miocene, a connection with the Central Paratethys and the Mediterranean at the beginning and middle part of the Konkian and the beginning of the ecological crisis in the Sarmatian. Based on the study of nannoplankton assemblages, auxiliary biostratigraphic units—Beds with nannoplankton—have been identified. The age and range of some regional members and their correlation with subdivisions of the Central Paratethys are emended.

Climate change could overturn bird migration: Transarctic flights and high-latitude residency in a sea ice free Arctic

Climate models predict that by 2050 the Arctic Ocean will be sea ice free each summer. Removing this barrier between the Atlantic and the Pacific will modify a wide range of ecological processes, including bird migration. Using published information, we identified 29 arctic-breeding seabird species, which currently migrate in the North Atlantic and could shift to a transarctic migration towards the North Pacific. We also identified 24 arctic-breeding seabird species which may shift from a migratory strategy to high-arctic year-round residency. To illustrate the biogeographical consequences of such drastic migratory shifts, we performed an in-depth study of little auks (Alle alle), the most numerous artic seabird. Coupling species distribution models and climatic models, we assessed the adequacy of future wintering and breeding areas for transarctic migrants and high-arctic year-round residents. Further, we used a mechanistic bioenergetics model (Niche Mapper), to compare the energetic costs of current little auk migration in the North Atlantic with potential transarctic and high-arctic residency strategies. Surprisingly, our results indicate that transarctic little auk migration, from the North Atlantic towards the North Pacific, may only be half as costly, energetically, than high-arctic residency or migration to the North Atlantic. Our study illustrates how global warming may radically modify the biogeography of migratory species, and provides a general methodological framework linking migratory energetics and spatial ecology.

Early Pleistocene divergence ofPelagia noctilucapopulations (Cnidaria, Medusozoa) between the Atlantic Ocean and the Mediterranean Sea

AbstractA previous study detected mixing of two deeply split mtDNA clades (Clade I and Clade II) for Atlantic and Mediterranean populations of the medusozoanPelagia noctiluca. The north hemisphere glaciations and the Messinian salinity crisis have been proposed as the two main biogeographic events related to the isolation between the Atlantic Ocean and the Mediterranean Sea. We tested if the splitting time between Clade I and Clade II ofP. noctilucawas associated with one of these geological events. Our study was based on DNA sequence data of mitochondrial (COI and 16S ribosomal RNA) and nuclear (18S ribosomal RNA, internal transcribed spacer 1 and 5.8S ribosomal RNA) genes from populations of the Atlantic and Pacific Ocean and the Mediterranean Sea. The rise of the Isthmus of Panama was used to calibrate substitution rates for COI. This calibration was based on the detection of a shallow but significant genetic structure betweenP. noctilucapopulations from the Pacific and the Atlantic Oceans. Considering our calibration for COI, we refute a possible origin of Clades I and II during the Messinian salinity crisis. Our estimates suggest the origin for a putative common ancestor of Clades I and II around 2.57 Ma (with 95% 2.91–2.22 HPD), roughly corresponding to the Gelasian stage of the early Pleistocene. These alterations include changes in the sea level and oceanic currents at the Strait of Gibraltar and other regions of the Mediterranean basin, and could explain the origin of the twoP. noctilucaclades.

Global biogeographical regions of freshwater fish species

AbstractAimTo define the major biogeographical regions and transition zones for freshwater fish species.TaxonStrictly freshwater species of actinopterygian fish (i.e. excluding marine and amphidromous fish families).MethodsWe based our bioregionalization on a global database of freshwater fish species occurrences in drainage basins, which, after filtering, includes 11,295 species in 2,581 basins. On the basis of this dataset, we generated a bipartite (basin‐species) network upon which we applied a hierarchical clustering algorithm (the Map Equation) to detect regions. We tested the robustness of regions with a sensitivity analysis. We identified transition zones between major regions with the participation coefficient, indicating the degree to which a basin has species from multiple regions.ResultsOur bioregionalization scheme showed two major supercontinental regions (Old World and New World, 50% species of the world and 99.96% endemics each). Nested within these two supercontinental regions lie six major regions (Nearctic, Neotropical, Palearctic, Ethiopian, Sino‐Oriental and Australian) with extremely high degrees of endemism (above 96% except for the Palearctic). Transition zones between regions were of limited extent compared to other groups of organisms. We identified numerous subregions with high diversity and endemism in tropical areas (e.g. Neotropical), and a few large subregions with low diversity and endemism at high latitudes (e.g. Palearctic).Main conclusionsOur results suggest that regions of freshwater fish species were shaped by events of vicariance and geodispersal which were similar to other groups, but with freshwater‐specific processes of isolation that led to extremely high degrees of endemism (far exceeding endemism rates of other continental vertebrates), specific boundary locations and limited extents of transition zones. The identified bioregions and transition zones of freshwater fish species reflect the strong isolation of freshwater fish faunas for the past 10–20 million years. The extremely high endemism and diversity of freshwater fish fauna raises many questions about the biogeographical consequences of current introductions and extinctions.

Phylogenetic relationships and historical biogeography of Oligosarcus (Teleostei: Characidae): Examining riverine landscape evolution in southeastern South America

The pike-characin Oligosarcus is a group of Characidae composed of 22 species, which have mostly allopatric distributed species in southeastern South America and sympatric occurrence of few species. Oligosarcus shares a similar distribution pattern with other fish genera and therefore, can help us to understand biogeographic events that influenced freshwater fish distribution in the southeastern South America. Our paper presents the most extensive taxonomic coverage for molecular analysis of Oligosarcus and uses various methods to examine the evolutionary history of the genus. Phylogenetic relationships among species of Oligosarcus were examined using a multilocus dataset by Maximum Likelihood and Bayesian methods. A relaxed molecular clock was used to estimate lineage divergence times, which provide a framework to examine the biogeographic history of this clade across the drainage basins of southeastern South America. Oligosarcus was resolved as monophyletic with strong support, and related to lineages currently assigned to the genus Astyanax. Within Oligosarcus, two groups of approximately equal species richness were resolved as monophyletic, mainly restricted to continental and coastal drainages of southeastern South America. Oligosarcus radiation is estimated to the late Neogene, with its origin in the Pliocene and most speciation events occurring in the Pleistocene. Some apomorphic characteristics associated with piscivory (e.g. large caniniform teeth) in Oligosarcus likely have evolved once, and are convergent to similar phenotypes observed in a distantly related clade of Astyanax (formerly Bramocharax). In addition, the presence of morphological convergence within the genus Oligosarcus (e.g. trophic morphology) seems to explain the difference between the present molecular hypothesis and some previous morphological studies. Ancestral geographical range estimation using analytical methods (e.g. DIVALIKE and DEC) demonstrated the effects of different Landscape Evolution Models (LEMs) on diversification of Oligosarcus. The results suggest that the two main Oligosarcus clades evolved in allopatry in continental and coastal drainages, with subsequent range extension and vicariance events that established the modern distributions. LEM analyses indicate the importance of formation of riverine barriers across the watershed of the La Plata basin and the effects of sea-level changes during the Pleistocene for delineating lineage distributions of Oligosarcus.

A complex pattern of post‐divergence expansion, contraction, introgression, and asynchronous responses to Pleistocene climate changes in two Dipelta sister species from western China

AbstractThe well‐known vicariance and dispersal models dominate in understanding the allopatric pattern for related species and presume the simultaneous occurrence of speciation and biogeographic events. However, the formation of allopatry could postdate the species divergence. We examined this hypothesis using DNA sequence data from three chloroplast fragments and five nuclear loci of Dipelta floribunda Maxim. and D. yunnanensis Franch, two shrub species with the circum Sichuan Basin distribution, combining the climatic niche modeling approach. The best‐fit model supported by the approximate Bayesian computation analysis indicated that D. floribunda and D. yunnanensis diverged during the mid‐Pleistocene period, consistent with the largest glacial period in the Qinghai–Tibet Plateau. The historically interspecific gene flow was identified, but seemed to have ceased after the last interglacial period, when the range of D. floribunda moved northward from the south of the Sichuan Basin. Furthermore, populations of D. floribunda had expanded obviously in the north of the Sichuan Basin after the last glacial maximum (LGM). Relatively, the range of D. yunnanensis expanded before the LGM, and reduced during the post‐LGM especially in the north of the Sichuan Basin, reflecting the asynchronous responses of related species to contemporary climate changes. Our results suggested that complex topography should be considered in understanding distributional patterns, even for closely related species and their demographic responses.

Molecular and morphological differentiation among Torrent Duck (Merganetta armata) populations in the Andes

AbstractBirds living in riverine environments may show weak population structure because high dispersal abilities required to track habitat dynamics can result in gene flow over broad spatial scales. Alternatively, the configuration of river networks may result in restricted dispersal within river courses or basins, leading to high genetic structure. Although several bird species are riverine specialists in the Andes, no study has extensively evaluated the population genetic structure of any of them. We examined evidence from genetic and morphological data to address questions about the biogeography and taxonomy of the Torrent Duck (Merganetta armata), a riverine specialist bird with a broad distribution in Andean riverine habitats which certainly comprises different subspecies and may comprise more than one species. We found deep subdivisions of Torrent Duck populations from the northern, central and southern portions of the Andes. These lineages, which partly coincide with subspecies described based on plumage variation and body size, do not share mtDNA haplotypes, have private nuclear alleles and exhibit marked differences in morphometric traits. Some geographic barriers presumably restricting gene flow between groups partially coincide with those associated with major genetic breaks in forest species with similar distributions along the Andes, suggesting that bird assemblages including species occupying different habitats were likely affected by common biogeographical events. The three groups of Torrent Ducks may be considered different species under some species definitions and are distinct evolutionary lineages to be conserved and managed separately.

A mirage of cryptic species: Genomics uncover striking mitonuclear discordance in the butterfly Thymelicus sylvestris

Mitochondrial DNA (mtDNA) sequencing has led to an unprecedented rise in the identification of cryptic species. However, it is widely acknowledged that nuclear DNA (nuDNA) sequence data are also necessary to properly define species boundaries. Next generation sequencing techniques provide a wealth of nuclear genomic data, which can be used to ascertain both the evolutionary history and taxonomic status of putative cryptic species. Here, we focus on the intriguing case of the butterfly Thymelicus sylvestris (Lepidoptera: Hesperiidae). We identified six deeply diverged mitochondrial lineages; three distributed all across Europe and found in sympatry, suggesting a potential case of cryptic species. We then sequenced these six lineages using double-digest restriction-site associated DNA sequencing (ddRADseq). Nuclear genomic loci contradicted mtDNA patterns and genotypes generally clustered according to geography, i.e., a pattern expected under the assumption of postglacial recolonization from different refugia. Further analyses indicated that this strong mtDNA/nuDNA discrepancy cannot be explained by incomplete lineage sorting, sex-biased asymmetries, NUMTs, natural selection, introgression or Wolbachia-mediated genetic sweeps. We suggest that this mitonuclear discordance was caused by long periods of geographic isolation followed by range expansions, homogenizing the nuclear but not the mitochondrial genome. These results highlight T.sylvestris as a potential case of multiple despeciation and/or lineage fusion events. We finally argue, since mtDNA and nuDNA do not necessarily follow the same mechanisms of evolution, their respective evolutionary history reflects complementary aspects of past demographic and biogeographic events.

Small-scale edaphic heterogeneity as a floristic–structural complexity driver in Seasonally Dry Tropical Forests tree communities

Our work aimed to test the hypothesis that soil microscale heterogeneity act as a community ecological driver, increasing diversity and promoting structural shifts on the Seasonally Dry Tropical Forest (SDTF) tree community. We evaluated the relationship between microscale edaphic variations and floristic–structural patterns of tree communities in a SDTF fragment located in the southern end of the Brazilian Caatinga domain. Vegetation and soil data were obtained through 27 sample units of 400 m2 (20 m × 20 m), within each one we measured and identified at species level all arboreal individuals with Circumference at the Breast Height greater or equal to 10 cm, and also collected the soil samples. Through the data we evaluated soil variation influence on the tree community structural and floristic patterns trough generalized linear models. Soil explained the small-scale structural and floristic variations, contributing significantly to biomass, sprouting and to floristic relationships between sample units. It was also observed a possible relation of the result with the Caatinga domain biogeographic history, due the presence of Sedimentary Caatinga species, which are not expected for the study region. Soil plays an important role in driving small-scale complexity and diversity of SDTF, but we also suggest that Caatinga biogeographic events have influence on the high heterogeneity patterns.

Genetic diversity among populations of the Western Atlantic mangrove crab Ucides cordatus (Linnaeus, 1763) (Decapoda: Brachyura: Ocypodidae): evidence for panmixia and useful data for future management and conservation

AbstractThe mangrove crab Ucides cordatus (Linnaeus, 1763) is a keystone species in mangroves, and recent changes in population sizes have been attributed primarily to overharvest, selective capture, and loss of habitat due to destruction of mangroves. We analyzed genetic variability and phylogeographic pattern among populations of U. cordatus along the western Atlantic coast in order to document levels of genetic differentiation, aiming to provide data to be used in future management and conservation strategies. MtDNA cytochrome oxidase I (COI) was analyzed and compared among populations. We computed a haplotype network, haplotype and nucleotide diversities, index of fixation, Mantel test, analysis of molecular variance (AMOVA), neutrality tests, and pairwise mismatch distributions under the sudden expansion model of demographic expansion; Maximum likelihood phylogenetic reconstruction was also undertaken for the haplotypes found. We found no geographic structure and no significant indication for restricted gene flow between populations from sites along a distance of 12,000 km, indicating that sampled individuals currently represent a single panmictic population. Demographic results revealed demographic expansion along the evolutionary history of U. cordatus, probably related to climatic biogeographic events. Although there is no current evidence of any substantial genetic break or of demographic reduction between the western Atlantic populations that we investigated, the genetic signal of regional population depletion warrants future monitoring in the course of resource management.

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.

Integrating historical biogeography and environmental niche evolution to understand the geographic distributionof Datureae.

The distributions of plant clades are shaped by abiotic and biotic factors as well as historical aspects such as center of origin. Dispersals between distant areas may lead to niche evolution when lineages are established in new environments. Alternatively, dispersing lineages may exhibit niche conservatism, moving between areas with similar environmental conditions. Here we test these contrasting hypotheses in the Datureae clade (Solanaceae). We used maximum likelihood methods to estimate the ancestral range of Datureae along with the history of biogeographic events. We then characterized the niche of each taxon using climatic and soil variables and tested for shifts in environmental niche optima. Finally, we examined how these shifts relate to the niche breadth of taxa and clades within Datureae and the degree of overlap between them. Datureae originated in the Andes and subsequently expanded its range to North America and non-Andean regions of South America. The ancestral niche, and that of most Datura and Trompettia species, is dry, while Brugmansia species likely shifted toward a more mesic environment. Nonetheless, most Datureae present moderate to high overlap in niche breadth today. The expansion of Datureae into North America was associated with niche conservatism, with dispersal into similarly dry areas as occupied by the ancestral lineage. Subsequent niche evolution, including the apparent shift to a mesic niche in Brugmansia, diversified the range of habitats occupied by species in the tribe Datureae but also led to significant niche overlap among the three genera.

Multiple colonizations, hybridization and uneven diversification in Cyrtandra (Gesneriaceae) lineages on Hawai'i Island

AbstractAimThe diversity and composition of species pools within oceanic archipelagos is determined by a combination of colonization, abiotic tolerance, in situ diversification, biotic interactions and extinction. The signature of biogeographic events and evolutionary processes, however, may be masked by recent coalescence and hybridization between closely related species. We used the species‐rich plant genus Cyrtandra (Gesneriaceae) to investigate the roles of colonization and hybridization in shaping community assemblages on the geologically young Hawai'i Island.LocationHawaiian Islands.TaxonCyrtandra (Gesneriaceae).MethodsWe sampled 29 Cyrtandra taxa and putative hybrids across the main Hawaiian Islands and generated single nucleotide polymorphisms (SNPs) from nine single‐copy nuclear genes. Maximum likelihood and Bayesian inference were used to reconstruct phylogenetic relationships, divergence times were estimated using secondary calibrations and island ages, and ancestral area estimation was done using likelihood models. Lastly, we used a Bayesian population assignment test and principal components analysis to infer population genetic structure.ResultsCyrtandra colonization of the main Hawaiian Islands appears to have followed the progression rule, whereby the oldest high Hawaiian Islands (Kaua'i and O'ahu) were colonized first, followed by colonization of the younger islands as habitat became available. Hawai'i Island was colonized four times, with two dispersal events from O'ahu and two from Maui Nui. The different colonization events gave rise to significantly uneven numbers of species, and hybridization among the incipient lineages was detected in the form of intermediate genotypes.Main conclusionsOur investigation into community assembly in a species‐rich plant genus on a geologically young oceanic island revealed a history of multiple colonizations and hybridization among colonizing lineages. The rapid diversification (3.5 species/My) of one of four Cyrtandra lineages on Hawai'i Island may be the result of hybridization between genetically diverse lineages that stem from independent colonization events. Multiple colonization events followed by a merging of lineages may be particularly common during early‐stage community assembly on islands and, through the generation of genetic variation, may be especially important for species diversification.

Phylogeography of eagle rays of the genus Aetobatus: Aetobatus narinari is restricted to the continental western Atlantic Ocean

The biogeography and conservation of elasmobranch species was increasingly addressed in the recent past, but the southwestern Atlantic Ocean fauna is still one of the least studied. Reliable delimitation of the distribution range of species is fundamental to conservation and development of fisheries management strategies. A recent molecular study of the cryptic Aetobatus narinari species complex restricted that species to western and eastern coasts of the New World. However, the current distribution of A. narinari and phylogenetic relationships within the genus Aetobatus have yet to be clarified, the goal of this phylogeographic analysis. Using mitochondrial and nuclear markers we investigated specimens from the Atlantic coast of Brazil and the Pacific coast of Mexico and related them to previously analyzed specimens from other regions. Our analysis indicates that Aetobatus narinari is present only in the western Atlantic, formed by a single genetic lineage that ranges between Florida and southeastern Brazil, while the Pacific New World lineage is in fact assigned to Aetobatus laticeps. Analysis of divergence times revealed that biogeographic events such as the closure of the Tethys Sea, the formation of the Benguela barrier, and the Isthmus of Panama played major roles in diversification and dispersal of the genus Aetobatus.

Reconstructing biogeographic temporal events in the evolution of the livebearer fish genus Jenynsia based on total evidence analysis (Cyprinodontiformes: Anablepidae)

The current distribution of the Neotropical ichthyofauna has been widely affected by the main geological events that occurred in South and Central America. However, robust biogeographic information is still scarce or absent for most fish families. The biogeographic relationships of the most diverse anablepid genus, Jenynsia, are herein analysed, using temporal and spatial approaches based on a total evidence dataset, including 167 morphological characters and seven nuclear genes, totalling 6075 bp. A time calibrated analysis recovered the origin of Jenynsia at the Miocene and the diversification of its two subgenera between the Late Miocene and Early Pliocene. This result combined with the analysis of reconstruction of ancestral states indicates that the ancestor of Jenynsia colonized the Paranean Sea, and the current distribution of the species of the genus is probably a result of geological events, including: (1) ancient connections between Iguaçu and upper Uruguay River basins; (2) sea level variation along the Pliocene in the South American Atlantic coast; and (3) the decrease of the Paranean Sea along the Pliocene and Pleistocene.

Historical Biogeography and Temporal Diversification in Symphoricarpos (Caprifolieae, Caprifoliaceae, Dipsacales)

Abstract—The major aim of this paper was to investigate temporal diversification within Symphoricarpos (Caprifoliaceae, Dipsacales). We used recently published molecular sequences, along with fossil data, to examine when Symphoricarpos may have arrived in the New World and if current distributional patterns can be explained by data based on biogeographic, climatological, and geological events. We simultaneously estimated the phylogeny and divergence times within Symphoricarpos and related Caprifolieae species using BEAST. Based on these phylogenetic and divergence time estimations we reconstructed ancestral areas using the dispersal-extinction-cladogenesis (DEC) method implemented in Lagrange. For Symphoricarpos, our phylogenetic results inferred using BEAST were in strong agreement with previous studies, with a well-supported clade containing the North American species that was sister to the lone Asian species. Our divergence time results suggest that the North American species originated in the late Oligocene to mid Miocene (12‐25 million years ago) and quickly diversified. The DEC area reconstructions suggest that after entering the North American continent from Asia, species of Symphoricarpos became widespread across the continent, followed by range restrictions to that of what we see today. Although several recent studies have argued for the idea of phylogenetic niche conservatism as a general explanation for characterizing broad biogeographic patterns, our data suggest significant niche evolution within the North American species of Symphoricarpos, especially in regard to taxa found in the southwestern parts of the USA and Mexico. These observed biome shifts from mesic forest habitats to a much drier habitat appear to have happened across a highly diverse landscape in which species of Symphoricarpos occur. These results, along with results from other plant taxa, support the hypothesis that a climate shift in western North America played a role in the assemblage of the current flora via migration, as well as in situ adaptation in combination with diversification.