Comparative Phylogeography Reveals Cryptic Diversity and Repeated Patterns of Cladogenesis for Amphibians and Reptiles in Northwestern Ecuador

Abstract

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.

Radiation of the polymorphic Little Devil poison frog (Oophaga sylvatica) in Ecuador

“…For instance, three river drainages separate the landscape, following the genetic clustering of our populations. The main river drainage composed of the Esmeraldas and Guayllabamba Rivers has been identified in the geographical pattern of differentiation in other frog species, such as Pristimantis nietoi and P. walkeri , populations of the snake Bothrops punctatus (Arteaga et al., 2016), and roughly separates the distribution range of O. sylvatica in two main groups (Figures 2 and 6). The northern genetic cluster (i.e., San Antonio, Lita, Alto Tambo, Durango, and Otokiki) and two populations from the southern genetic cluster (i.e., Felfa and Cristóbal Colón) are located north of Esmeraldas River, with the rest of the southern cluster (i.e., Simón Bolívar, Puerto Quito, Cube, Quingüe, Santo Domingo, and La Maná) in the south.…”

“…(2016). They identified several geographical barriers to dispersion, especially river drainages, and their data suggests that diversification also follows thermal elevation gradients between the Chocoan region and the Andes.…”

“…Further behavioral, ecological, and morphological information is required to determine whether the two geographical lineages observed in Oophaga sylvatica represent one polymorphic or several species. A combination of climatic gradient and structured landscape generating geographic barriers to gene flow could explain the complex patterns of diversification observed in Oophaga and some other Dendrobatidae (Arteaga et al., 2016; Posso‐Terranova & Andrés, 2016a, 2016b). (2) The northern and southern populations show different amounts of structure, which may reflect more recent range expansions in the south.…”

Species limits within the widespread Amazonian treefrog Dendropsophus parviceps with descriptions of two new species (Anura, Hylidae)

“…Some studies have shown that sister species tend to segregate along environmental gradients suggesting ecological speciation and niche lability (Arteaga et al 2016; Graham et al 2004; Ron et al 2012). Other studies have shown that sister species tend to be allopatric but with similar environmental niches (Cadena et al 2012; Ortega-Andrade et al 2015).…”

A new cryptic species of Anolis lizard from northwestern South America (Iguanidae, Dactyloinae)

“…This finding suggests that other cryptic species of anoles from the Tropical Andes are yet to be discovered, as has been the case in other taxa (e.g. Guayasamin et al 2015; Arteaga et al 2016; Guayasamin et al 2017), and we highlight the importance of building modern specimen collections of supposedly known species (e.g., A.aequatorialis ), particularly from poorly explored areas. After extensive geographical sampling, we conclude that the new species described in this paper occurs only north of the Mira River Basin in northern Ecuador (Figure 13).…”