Taxonomic Review of South American Butter Frogs: Phylogeny, Geographic Patterns, and Species Delimitation in the Leptodactylus latrans Species Group (Anura: Leptodactylidae)

The Leptodactylus latrans species group currently comprises eight medium- to large-sized frog species with a convoluted taxonomic history, particularly related to the specific limits of the L. latrans complex, and the species pair Leptodactylus chaquensis–Leptodactylus macrosternum. Their homogeneous external morphology and continental geographic distribution in South America have posed severe limitations to a comprehensive review, such that taxonomic consensus and species limits remain uncertain. This is further worsened by the presence of chromatic polymorphism among coexisting species that can hardly be distinguished by external morphology. Based on a large-scale geographic sampling including multilocus DNA analyses, and acoustic and morphological data, we provide a comprehensive evaluation of the taxonomic status and species limits of the L. latrans group, focusing on the resolution of the L. latranscomplex and the species pair L. chaquensis–L. macrosternum. We gathered 728 mitochondrial sequences from 429 localities, encompassing the entire geographic distribution of the group. Both generalized mixed Yule coalescent and automatic barcode gap discovery species delimitation methods recovered four major mitochondrial evolutionary lineages within the L. latrans complex, also supported by distribution patterns, multilocus molecular, morphological and/or bioacoustic data. One lineage is linked to nominal L. latrans,one revalidated as Leptodactylus luctator, and the other two are formally named and described. Another lineage encompasses all specimens previously assigned to the species pair L. chaquensis–L. macrosternum, clustered as a single evolutionary entity and is now regarded as L. macrosternum. We provide a revised diagnosis for these species based on acoustic data, morphological/chromatic variation, and phylogenetic relationships of all species currently included in the L. latrans group. Our findings reinforce the view that Neotropical diversity is highly underestimated and stress that appropriate geographic sampling in an integrative framework is crucial for the establishment of specific limits among broadly distributed and morphologically cryptic Neotropical frogs

High Levels of Diversity Uncovered in a Widespread Nominal Taxon: Continental Phylogeography of the Neotropical Tree Frog

Species distributed across vast continental areas and across major biomes provide unique model systems for studies of biotic diversification, yet also constitute daunting financial, logistic and political challenges for data collection across such regions. The tree frog Dendropsophus minutus (Anura: Hylidae) is a nominal species, continentally distributed in South America, that may represent a complex of multiple species, each with a more limited distribution. To understand the spatial pattern of molecular diversity throughout the range of this species complex, we obtained DNA sequence data from two mitochondrial genes, cytochrome oxidase I (COI) and the 16S rhibosomal gene (16S) for 407 samples of D. minutus and closely related species distributed across eleven countries, effectively comprising the entire range of the group. We performed phylogenetic and spatially explicit phylogeographic analyses to assess the genetic structure of lineages and infer ancestral areas. We found 43 statistically supported, deep mitochondrial lineages, several of which may represent currently unrecognized distinct species. One major clade, containing 25 divergent lineages, includes samples from the type locality of D. minutus. We defined that clade as the D. minutus complex. The remaining lineages together with the D. minutus complex constitute the D. minutus species group. Historical analyses support an Amazonian origin for the D. minutus species group with a subsequent dispersal to eastern Brazil where the D. minutus complex originated. According to our dataset, a total of eight mtDNA lineages have ranges >100,000 km2. One of them occupies an area of almost one million km2 encompassing multiple biomes. Our results, at a spatial scale and resolution unprecedented for a Neotropical vertebrate, confirm that widespread amphibian species occur in lowland South America, yet at the same time a large proportion of cryptic diversity still remains to be discovered

The First Bromeligenous Species of Dendropsophus (Anura: Hylidae) from Brazil\u27s Atlantic Forest

We describe a new treefrog species of Dendropsophus collected on rocky outcrops in the Brazilian Atlantic Forest. Ecologically, the new species can be distinguished from all known congeners by having a larval phase associated with rainwater accumulated in bromeliad phytotelms instead of temporary or lentic water bodies. Phylogenetic analysis based on molecular data confirms that the new species is a member of Dendropsophus; our analysis does not assign it to any recognized species group in the genus. Morphologically, based on comparison with the 96 known congeners, the new species is diagnosed by its small size, framed dorsal color pattern, and short webbing between toes IV-V. The advertisement call is composed of a moderate-pitched two-note call (~5 kHz). The territorial call contains more notes and pulses than the advertisement call. Field observations suggest that this new bromeligenous species uses a variety of bromeliad species to breed in, and may be both territorial and exhibit male parental care

Demographic histories and genetic diversity across pinnipeds are shaped by human exploitation, ecology and life-history

A central paradigm in conservation biology is that population bottlenecks reduce genetic diversity and population viability. In an era of biodiversity loss and climate change, understanding the determinants and consequences of bottlenecks is therefore an important challenge. However, as most studies focus on single species, the multitude of potential drivers and the consequences of bottlenecks remain elusive. Here, we combined genetic data from over 11,000 individuals of 30 pinniped species with demographic, ecological and life history data to evaluate the consequences of commercial exploitation by 18th and 19th century sealers. We show that around one third of these species exhibit strong signatures of recent population declines. Bottleneck strength is associated with breeding habitat and mating system variation, and together with global abundance explains much of the variation in genetic diversity across species. Overall, bottleneck intensity is unrelated to IUCN status, although the three most heavily bottlenecked species are endangered. Our study reveals an unforeseen interplay between human exploitation, animal biology, demographic declines and genetic diversity

High levels of diversity uncovered in a widespread nominal taxon: Continental phylogeography of the neotropical tree frog dendropsophus minutus

Species distributed across vast continental areas and across major biomes provide unique model systems for studies of biotic diversification, yet also constitute daunting financial, logistic and political challenges for data collection across such regions. The tree frog Dendropsophus minutus (Anura: Hylidae) is a nominal species, continentally distributed in South America, that may represent a complex of multiple species, each with a more limited distribution. To understand the spatial pattern of molecular diversity throughout the range of this species complex, we obtained DNA sequence data from two mitochondrial genes, cytochrome oxidase I (COI) and the 16S rhibosomal gene (16S) for 407 samples of D. minutus and closely related species distributed across eleven countries, effectively comprising the entire range of the group. We performed phylogenetic and spatially explicit phylogeographic analyses to assess the genetic structure of lineages and infer ancestral areas. We found 43 statistically supported, deep mitochondrial lineages, several of which may represent currently unrecognized distinct species. One major clade, containing 25 divergent lineages, includes samples from the type locality of D. minutus. We defined that clade as the D. minutus complex. The remaining lineages together with the D. minutus complex constitute the D. minutus species group. Historical analyses support an Amazonian origin for the D. minutus species group with a subsequent dispersal to eastern Brazil where the D. minutus complex originated. According to our dataset, a total of eight mtDNA lineages have ranges >100,000 km2. One of them occupies an area of almost one million km2 encompassing multiple biomes. Our results, at a spatial scale and resolution unprecedented for a Neotropical vertebrate, confirm that widespread amphibian species occur in lowland South America, yet at the same time a large proportion of cryptic diversity still remains to be discovered. © 2014 Gehara et al

The riverine thruway hypothesis: rivers as a key mediator of gene flow for the aquatic paradoxical frog Pseudis tocantins (Anura, Hylidae)

Context: Rivers, landscape, and climate can alter patterns of gene flow and consequently, shape intraspecific genetic variation. While rivers are predicted to halt gene flow in terrestrial species, they may facilitate migration for aquatic species. Amphibians are usually seen as water-dependent, yet multiple studies have indicated that rivers exert a barrier effect on these organisms. Objectives: In this study, we investigated the effects of rivers and other abiotic factors, such as climate and geography on genetic variation of a highly aquatic frog (Pseudis tocantins) inhabiting central Brazil. Methods: We sequenced fragments of one mitochondrial and two nuclear genes of 179 individuals of P. tocantins from 19 localities along the Tocantins-Araguaia Basin in Brazil and used Generalized Dissimilarity Modeling (GDM) to test the role of rivers, landscape, and climate features on its genetic differentiation. Next, we tested three scenarios of migration along the Tocantins-Araguaia Basin using approximate Bayesian computation (ABC). Results: We found that genetic differentiation among localities is mostly explained by the influence of river connectivity. Conversely, elevation, slope, and past and current climate have little or no impact on genetic differentiation. Furthermore, our results show that patterns of migration took place directionally, from upstream to downstream sites. Conclusions: Rivers have shaped patterns of intraspecific diversity in P. tocantins by acting as the most important facilitator of gene flow. Therefore, we suggest that future research should include the role of rivers as a facilitator of gene flow, especially for those species that are associated with aquatic environments.Fil: Fonseca, Emanuel M.. Ohio State University; Estados UnidosFil: Garda, Adrian A.. Universidade Federal do Rio Grande do Norte; BrasilFil: Oliveira, Eliana F.. Universidade Federal do Mato Grosso do Sul; BrasilFil: Camurugi, Felipe. Universidade Federal do Mato Grosso do Sul; BrasilFil: Magalhães, Felipe de M.. Universidade Estadual da Paraiba; BrasilFil: Lanna, Flávia M.. Ohio State University; Estados UnidosFil: Zurano, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; ArgentinaFil: Marques, Ricardo. Universidade Estadual da Paraiba; BrasilFil: Vences, Miguel. Universidad Técnica de Brunswick; AlemaniaFil: Gehara, Marcelo. Rutgers University newark; Estados Unido

Diversification with gene flow and niche divergence in a lizard species along the South American “diagonal of open formations”

Aim: To assess the effects of historical events on the tempo and mode of diversification of the lizard Polychrus acutirostris along the South American diagonal of open formations (DOF). Location: Caatinga and Cerrado biomes in Brazil. Methods: We sequenced fragments of one mtDNA and three nuDNA genes of 68 individuals from 33 localities. We used population assignment methods to access genetic structure and estimate lineage boundaries. Next, we estimated lineage relationships, intraspecific diversity, environmental niche similarity and demographic history. Finally, we tested 12 diversification scenarios using an approximate Bayesian computation (ABC) approach. Results: We recovered three non-overlapping, geographically structured lineages corresponding to Caatinga, north-east Cerrado and south-west Cerrado, with the major divergence event dating to the Late Neogene. We also recovered a complex scenario of divergence associated with gene flow and niche divergence. Main conclusions: We show a complex history of diversification along the South American DOF. Our findings support the role of environmental features as the likely drivers of P. acutirostris intraspecific diversification during the Late Neogene. © 2018 John Wiley & Sons Lt

Dwarf geckos and giant rivers: The role of the São Francisco River in the evolution of Lygodactylus klugei (Squamata: Gekkonidae) in the semi-arid Caatinga of north-eastern Brazil

Species diversification can be strongly influenced by geomorphological features, such as mountains, valleys and rivers. Rivers can act as hard or soft barriers to gene flow depending on their size, speed of flow, historical dynamics and regional topographical characteristics. The São Francisco River (SFR) is the largest perennial river in the Caatinga biome in north-eastern Brazil and has been considered a barrier to gene flow and dispersal. Herein, we evaluated the role of the SFR on the evolution of Lygodactylus klugei, a small gecko from the Caatinga. Using a single-locus species delimitation method (generalized mixed Yule coalescent), we defined lineages (haploclades). Subsequently, we evaluated the role of the SFR in structuring genetic diversity in this species using a multilocus approach to quantify migration across margins. We also evaluated genetic structure based on nuclear markers, testing the number of populations found through an assignment test (STRUCTURE) across the species distribution. We recovered two mitochondrial lineages structured with respect to the SFR, but only a single population was inferred from nuclear markers. Given that we detected an influence of the SFR only on mitochondrial markers, we suggest that the current river course has acted as a relatively recent geographical barrier for L. klugei, for ~450 000 years. © 2019 The Linnean Society of London, Biological Journal of the Linnean Society

The evolutionary history of Lygodactylus lizards in the South American open diagonal

The Pleistocenic Arc Hypothesis (PAH) posits that South American Seasonally Dry Tropical Forests (SDTF) were interconnected during Pleistocene glacial periods, enabling the expansion of species ranges that were subsequently fragmented in interglacial periods, promoting speciation. The lizard genus Lygodactylus occurs in Africa, Madagascar, and South America. Compared to the high diversity of African Lygodactylus, only two species are known to occur in South America, L. klugei and L. wetzeli, distributed in SDTFs and the Chaco, respectively. We use a phylogenetic approach based on mitochondrial (ND2) and nuclear (RAG-1) markers covering the known range of South American Lygodactylus to investigate (i) if they are monophyletic relative to their African congeners, (ii) if their divergence is congruent with the fragmentation of the PAH, and (iii) if cryptic diversity exists within currently recognized species. Maximum likelihood and Bayesian phylogenetic analyses recovered a well-supported monophyletic South American Lygodactylus, presumably resulting from a single trans-Atlantic dispersal event 29 Mya. Species delimitation analyses supported the existence of five putative species, three of them undescribed. Divergence times among L. klugei and the three putative undescribed species, all endemic to the SDTFs, are not congruent with the fragmentation of the PAH. However, fragmentation of the once broader and continuous SDTFs likely influenced the divergence of L. wetzeli in the Chaco and Lygodactylus sp. 3 (in a SDTF enclave in the Cerrado). © 2018 Elsevier Inc