Comparative phylogeography allow us to understand how shared historical circumstances have shaped the formation of lineages, by examining a broad spectrum of co-distributed populations of different taxa. However, these types of studies are scarce in the Neotropics, a region that is characterized by high diversity, complex geology, and poorly understood biogeography. Here, we investigate the diversification patterns of five lineages of amphibians and reptiles, co-distributed across the Choco and Andes ecoregions in northwestern Ecuador. Mitochondrial DNA and occurrence records were used to determine the degree of geographic genetic divergence within species. Our results highlight congruent patterns of parapatric speciation and common geographical barriers for distantly related taxa. These comparisons indicate similar biological and demographic characteristics for the included clades, and reveal the existence of two new species of Pristimantis previously subsumed under P. walkeri, which we describe herein. Our data supports the hypothesis that widely distributed Chocoan taxa may generally experience their greatest opportunities for isolation and parapatric speciation across thermal elevational gradients. Finally, our study provides critical information to predict which unstudied lineages may harbor cryptic diversity, and how geology and climate are likely to have shaped their evolutionary history.
We describe a new frog, Pristimantis mutabilis sp. nov., from the Andes of Ecuador. Individuals of the new species are remarkable for their ability to change skin texture from tuberculate to almost smooth in a few minutes, being the first documented amphibian species to show such dramatic phenotypic plasticity. The new taxon is assigned to the P. myersi group. It differs from other members of its group by body size (adult males 17.2-17.4 mm; adult females 20.9-23.2 mm), arboreal habitat, and red flash coloration in females. We document three call types for the new species, which differ through their number of notes and amplitude peaks. The three types are pulsed calls that share a dominant frequency of 3186.9-3445.3 Hz. Surprisingly, we also document similar skin texture plasticity in species (P. sobetes) from a different species group, suggesting that this ability might be more common than previously thought. The discovery of these variable species poses challenges to amphibian taxonomists and field biologists, who have traditionally used skin texture and presence/absence of tubercles as important discrete traits in diagnosing and identifying species. Reciprocal monophyly and genetic distances also support the validity of the new species, as it has distances of 15.1-16.3% (12S) and 16.4-18.6% (16S) from the most similar species, Pristimantis verecundus. Additionally, each of the two known populations of Pristimantis mutabilis are reciprocally monophyletic and exhibit a high genetic distance between them (5.0-6.5%). This pattern is best explained by the presence of a dry valley (Guayllabamba River) that seems to be acting as a dispersal barrier. Scenario 1: double origin Scenario 2: single origin P. buckleyi (KU 217836 P. sp. "mashpi" (MZUTI 635) P. surdus (KU 177847) P. hectus (UVC 15843) P. cf. verecundus (QCAZ 12410) P. cf. curtipes (KU 217869 P. sobetes (MZUTI 447) P. thymelensis (TNHC-GDC 14370) P. jubatus (UVC 15919) P. jubatus (UVC 15903) P. hectus (UVC 15943) P. sp. "mashpi" (MZUTI 634) P. ocreatus (KU 208508) P. verecundus (MZUTI 539) P. eriphus (QCAZ 32705) P. gentryi (KU 218109) P. cf. curtipes (KU 217871) P. sp. "mashpi" (MZUTI 633) P. sobetes (MZUTI 471) P. sobetes (MZUTI 542) P. truebae (KU 218013) P. sobetes (MZUTI 446) P. mutabilis (MZUTI 2190) P. sobetes (MZUTI 432) P. pyrrhomerus (KU 218030) P. mutabilis (MZUTI 910) P. supernatis (WED 52961) P. sobetes (MZUTI 442) P. jubatus (UVC 15917) P. eriphus (JJM 210) P. mutabilis (MZUTI 909) P. sp. "mashpi" (MZUTI 636) P. surdus (JDL 8862) P. mutabilis (MZUTI 911) P. devillei (JDL 9416 P. vertebralis (KU 177972 P. mutabilis (MZUTI 912) P. cf. thymelensis (QCAZ 16428) P. jubatus (UVC 15911) P. celator (KU 177684) P. thymalopsoides (KU 177861) P. thymelensis (KU 202519) P. verecundus (MZUTI 540) P. leoni (KU 218227) P. verecundus (MZUTI 2114) P. verecundus (MZUTI 541) P. hectus (UVC 15942) P. jubatus (UVC 15920) P. quinquagesimus (KU 179374) P. sobetes (MZUTI 439) P. mutabilis (MZUTI 2191) P. duellmani (WED 53050) P. sobetes (MZUTI 558) P. devillei (KU 2179...
Geographic barriers and elevational gradients have long been recognized as important in species diversification. Here, we illustrate an example where both mechanisms have shaped the genetic structure of the Neotropical rainfrog, Pristimantis ornatissimus, which has also resulted in speciation. This species was thought to be a single evolutionary lineage distributed throughout the Ecuadorian Chocó and the adjacent foothills of the Andes. Based on recent sampling of P. ornatissimus sensu lato, we provide molecular and morphological evidence that support the validity of a new species, which we name Pristimantis ecuadorensis sp. nov. The sister species are elevational replacements of each other; the distribution of Pristimantis ornatissimus sensu stricto is limited to the Ecuadorian Chocó ecoregion (< 1100 m), whereas the new species has only been found at Andean localities between 1450–1480 m. Given the results of the Multiple Matrix Regression with Randomization analysis, the genetic difference between P. ecuadorensis and P. ornatissimus is not explained by geographic distance nor environment, although environmental variables at a finer scale need to be tested. Therefore this speciation event might be the byproduct of stochastic historic extinction of connected populations or biogeographic events caused by barriers to dispersal such as rivers. Within P. ornatissimus sensu stricto, morphological patterns and genetic structure seem to be related to geographic isolation (e.g., rivers). Finally, we provide an updated phylogeny for the genus, including the new species, as well as other Ecuadorian Pristimantis.
We present a new molecular phylogeny of the stream treefrog genus Hyloscirtus, with an improved taxon sampling in the Hyloscirtus bogotensis group. The tree supports the existence of three clades within the genus (Hyloscirtus armatus group, H. bogotensis group and Hyloscirtus larinopygion group) in congruence with previous studies, and suggests the presence of at least three new species in the H. bogotensis group. Herein, we describe one of these species, Hyloscirtus mashpi n. sp. from the Pacific slope of the Ecuadorian Andes. The validity of the latter is supported by molecular, morphological and acoustic data. We also tested individuals of the new species for the chytrid fungus Batrachochytrium dendrobatidis, finding a prevalence of 17.6% (6 positives and 28 negatives). However, at sampled streams, frog densities were high, suggesting that H. mashpi n. sp. may be tolerant to the infection.
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