Major Caribbean and Central American frog faunas originated by ancient oceanic dispersal

Abstract

Approximately one-half of all species of amphibians occur in the New World tropics, which includes South America, Middle America, and the West Indies. Of those, 27% (801 species) belong to a large assemblage, the eleutherodactyline frogs, which breed out of water and lay eggs that undergo direct development on land. Their wide distribution and mode of reproduction offer potential for resolving questions in evolution, ecology, and conservation. However, progress in all of these fields has been hindered by a poor understanding of their evolutionary relationships. As a result, most of the species have been placed in a single genus, Eleutherodactylus, which is the largest among vertebrates. Our DNA sequence analysis of a major fraction of eleutherodactyline diversity revealed three large radiations of species with unexpected geo- amphibian ͉ anura ͉ biogeography ͉ Eleutherodactylus T he evolutionary tree of amphibians is now being revealed at a rapid pace, largely from DNA sequence analyses (1-5). However, the evolutionary history of a major assemblage of frogs is not well understood. These are the eleutherodactylines and the related genus Brachycephalus, which comprise 13% (812 sp.) of all known species of amphibians and 27% of those occurring in the New World tropics (6). Unlike most temperate species, these frogs reproduce on land and undergo direct development, bypassing the tadpole stage (7). Most are relatively small, typically 20-50 mm in length. A majority of the species has been placed in Eleutherodactylus and, together with several other genera, assigned to the tribe Eleutherodactylini of the neobatrachian family Leptodactylidae (8), superfamily Hyloidea (9). However, molecular phylogenies of small sets of representative species over the last two decades have suggested that both the family-level and genus-level classification is in need of revision (2,(10)(11)(12)(13)(14).Terrestrial breeding and direct development have allowed eleutherodactyline frogs to occupy a diversity of ecological niches and have facilitated their wide distribution (Fig. 1). Eleutherodactylines occur on almost every island in the Caribbean and display near total endemicity to single-island banks. Their elevational range also is broad, with some species occurring up to 4,400 m in the Andes of South America. Thus, they are a model group for studying Neotropical biogeography and evolution. With this in mind, we assembled samples and available sequences of 276 species of eleutherodactylines and Brachycephalus for several mitochondrial and nuclear genes. Our goal was to identify the major groups of species and their times of divergence, to better understand the historical biogeography of eleutherodactyline frogs and the region in general. Our results revealed several major and, for the most part, geographically isolated, clades of eleutherodactyline frogs and showed that the Middle American and West Indian eleutherodactylines owe their origin to Cenozoic over-water dispersal, not from land connections in the Mesozoic.

Are islands the end of the colonization road?

“…More than a third of the studies show evidence of reverse colonization, revealing continental lineages nested within island clades (shown in bold in Table 1). The clearest examples included birds (bananaquit [30], flycatchers [31], monarch flycatchers [10], parrots [32], Darwin's finches [33], catbirds [34] and orioles [35]), lizards [11,36], frogs [9,37], short-faced bats [38], drosophilid flies [39] and turtles [40]. Only a few of these studies explicitly discussed the phenomenon of reverse colonization [10,11,39].…”

Species richness, relative abundance, and habitat of reproduction of terrestrial frogs in the Triângulo Mineiro region, Cerrado biome, southeastern Brazil

“…In southeastern Brazil there are approximately 20 Ischnocnema species (FROST, 2007;HEINICKE et al, 2007), of which 19 are forest dwellers. The number of Brachycephalidae species in open areas, which includes most of the Cerrado physiognomies, may be constrained by their terrestrial reproductive mode, which relies on consistently high humidity (LYNCH & DUELLMAN, 1997).…”

Eleutherodactylus frogs show frequency but no temporal partitioning: implications for the acoustic niche hypothesis

“…All the species of Puerto Rico are closely related (Heinicke et al, 2007;Hedges et al, 2008), most call at the same period of the night, and they are the majority 181 of the anuran fauna in the island. These qualities reduce the added complexity of previous studies that compared 182 communities comprised of several families (Gerhardt and Schwartz, 1995;Chek et al, 2003).…”