Polyandry, Predation, and the Evolution of Frog Reproductive Modes

Area of Science:

• Evolutionary biology
• Herpetology
• Sexual selection

Background:

• Frog reproductive modes are diverse, with a trend towards terrestrial breeding, often linked to reduced predation.
• Previous theories emphasized natural selection (predation) as the primary driver of this evolutionary pattern.

Purpose of the Study:

• To investigate the role of sexual selection, specifically reduced polyandry, in the evolution of terrestrial breeding in frogs.
• To test if mating behaviors are correlated with egg and tadpole development sites in two frog families.

Main Methods:

• Reconstructed the evolutionary history of reproductive diversity in Hylidae and Leptodactylidae frog families.
• Analyzed the correlation between oviposition/tadpole development sites and mating behaviors (e.g., amplexus type).
• Compared testes mass in relation to mating system vulnerability to polyandry in hylids.

Main Results:

• Oviposition and tadpole development sites evolve independently, suggesting different selective pressures.
• Terrestrial egg deposition is linked to mating behaviors that reduce male competition.
• Males with exposed amplexus (vulnerable to polyandry) showed larger, more variable testes mass in hylids.

Conclusions:

• Intrasexual selection is an underappreciated factor in the diversification of frog reproductive strategies.
• Sexual selection may favor terrestrial breeding by mitigating fitness losses associated with polyandry.