Parental care and the evolution of terrestriality in frogs.

Balázs Vági,Tamás Székely,András Liker,Robert P Freckleton,Zsolt Végvári

doi:10.1098/rspb.2018.2737

Abstract

Frogs and toads (Anura) exhibit some of the most diverse parental strategies in vertebrates. Identifying the evolutionary origins of parenting is fundamental to understanding the relationships between sexual selection, social evolution and parental care systems of contemporary Anura. Moreover, parenting has been hypothesized to allow the invasion of terrestrial habitats by the ancestors of terrestrial vertebrates. Using comprehensive phylogenetic analyses of frogs and toads based on data from over 1000 species that represent 46 out of 55 Anura families, we test whether parental care is associated with terrestrial reproduction and several life-history traits. Here, we show that both the duration of care and offspring protection by males and females have coevolved with terrestrial reproduction. Sexual size dimorphism is also related to care, because the large male size relative to female size is associated with increased paternal care. Furthermore, increased egg size and reduced clutch volume are associated with increased care in bivariate but not in multivariate analyses, suggesting that the relationships between care, egg size and clutch volume are mediated by terrestrial reproduction. Taken together, our results suggest that parenting by males and females has coevolved, and complex parenting traits have evolved several times independently in Anura in response to breeding in terrestrial environments.

Highlights

Parental care is a highly diverse social behaviour that has evolved to increase offspring survival, it tends to be costly to the care giving parent [1,2,3]
Members of the genus Pipa which lay eggs in water and broods by aquatic parents were considered aquatic breeders. We established these categories because anuran eggs are adapted primarily to aquatic development and placing them outside water exposes them to hostile conditions, and we considered the strategy for this challenge as an important aspect of parental care
In contrast to reptiles and mammals, in which the females are the main care provider, or to birds in which biparental care is the predominant form of care [9,62], in frogs female-only, male-only and biparental care are all widespread among various lineages, and the involvement of males and females in care is comparable

Summary

Introduction

Parental care is a highly diverse social behaviour that has evolved to increase offspring survival, it tends to be costly to the care giving parent [1,2,3]. We investigate whether lifehistory variables including egg size and clutch size correlate with the duration of care, protection and nourishment provided by any of the parents. Large size in males is associated with high reproductive success in several species of frogs (reviewed by [5,35]) owing to competition for mates or female choice [36 –39], with the latter processes being clearly linked to sexual selection. To address these objectives, we use a comprehensive dataset that represents 46 out of 55 extant anuran families. All analyses were carried out using R v. 3.1.0 [55] with the ‘caper’ package [60]

Results

H I Afrobatrachia

Discussion

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