Male‐male competition and repeated evolution of terrestrial breeding in Atlantic Coastal Forest frogs*

Abstract

Terrestrial breeding is a derived condition in frogs, with multiple transitions from an aquatic ancestor. Shifts in reproductive mode often involve changes in habitat use, and these are typically associated with diversification in body plans, with repeated transitions imposing similar selective pressures. We examine the diversification of reproductive modes, male and female body sizes, and sexual size dimorphism (SSD) in the Neotropical frog genera Cycloramphus and Zachaenus, both endemic to the Atlantic rainforest of Brazil. Species in this clade either breed in rocky streams (saxicolous) or in terrestrial environments, allowing us to investigate reproductive habitat shifts. We constructed a multilocus molecular phylogeny and inferred evolutionary histories of reproductive habitats, body sizes, and SSD. The common ancestor was small, saxicolous, and had low SSD. Terrestrial breeding evolved independently three times and we found a significant association between reproductive habitat and SSD, with shifts to terrestrial breeding evolving in correlation with decreases in male body size, but not female body size. Terrestrial breeding increases the availability of breeding sites and results in concealment of amplexus, egg‐laying, and parental care, therefore reducing male‐male competition at all stages of reproduction. We conclude that correlated evolution of terrestrial reproduction and small males is due to release from intense male‐male competition that is typical of exposed saxicolous breeding.

The tadpole of an insular population of Cycloramphus boraceiensis Heyer, 1983 (Anura: Cycloramphidae) with a review of larval descriptions for species in the genus

“…Furthermore, we provide a comparison between the new data gathered and that of Heyer (1983a), and data gathered from the literature for other tadpoles of Cycloramphus. As a side note, it has been suggested that Cycloramphus boraceiensis may represent a complex of species, based on DNA sequences and cytogenetic information for distinct populations from São Paulo and one from Rio de Janeiro, (see Noleto et al, 2011;de Sá et al, 2019). We are aware that the described population of Cycloramphus boraceiensis larvae is indeed away from the species type locality.…”

For neither heat nor water conservation: Body size variation in Atlantic Forest frogs does not follow a general mechanism

“…Similarly, C. eleutherodactylus and I. guentheri represent species complexes with unclear species delimitations, following morphometric, bioacoustic and genetic studies (Gehara et al, 2013;Heyer, 1983;Kwet & Solé, 2005;de Sá et al, 2020). We sampled all specimens identified as belonging to C. eleutherodactylus (n = 48) and I. guentheri complexes (n = 166).…”

Shape Evolution in Two Acts: Morphological Diversity of Larval and Adult Neoaustraranan Frogs

“…These frogs are typical inhabitants of forested areas, with species associated with leaf litter, rocky outcrops, or swift streams [20][21][22][23][24]. Adult specimens breed in aquatic or terrestrial environments [20,22,25], five of them having semifossorial habits (gr. C. bolitoglossus) [20,22,26,27].…”