Surf and turf: predation by egg-eating snakes has led to the evolution of parental care in a terrestrial lizard

David A Pike,Jung-Ya Hsu,Hui-Yun Tseng,Rulon W Clark,Andrea Manica,Wen-San Huang

doi:10.1038/srep22207

Abstract

Animals display a great diversity of parental care tactics that ultimately enhance offspring survival, but how such behaviors evolve remains unknown for most systems. Here, we studied the evolution of maternal care, in the form of nest guarding, in a single population of long-tailed sun skink (Eutropis longicaudata) living on Orchid Island (Taiwan). This species typically does not provide protection to its offspring. Using a common garden experiment, we show that maternal care is genetically determined in this population. Through field manipulations, we demonstrate that care provides a significant increase in egg survival on Orchid Island by reducing predation from egg-eating snakes (Oligodon formosanus); this predator is not abundant in other populations of the lizard, which do not display parental care. Finally, using extensive field surveys, we show that the seasonal availability of green sea turtle (Chelonia mydas) nests is the cause for the high abundance of snake predators on Orchid Island, with the snakes consuming lizard eggs when green turtle eggs are not available. Together, these lines of evidence provide the first full demonstration of how predation can trigger the evolution of parental care in a species derived from a non-caring ancestor.

Highlights

Animals display a great diversity of parental care tactics that enhance offspring survival, but how such behaviors evolve remains unknown for most systems
When confronted with egg-eating snakes, all 10 females from Orchid island violently attacked snakes, thereby demonstrating egg-guarding behaviour, but none of the females from the other two sites did so, indicating that the guarding behaviour has a genetic basis despite the low level of overall genetic differentiation among these populations[28]
Egg guarding by mother lizards on Orchid Island has a genetic basis, despite the low level of genetic differentiation among lizard populations and lack of maternal care in other populations[28]

Summary

Introduction

Animals display a great diversity of parental care tactics that enhance offspring survival, but how such behaviors evolve remains unknown for most systems. Using extensive field surveys, we show that the seasonal availability of green sea turtle (Chelonia mydas) nests is the cause for the high abundance of snake predators on Orchid Island, with the snakes consuming lizard eggs when green turtle eggs are not available Together, these lines of evidence provide the first full demonstration of how predation can trigger the evolution of parental care in a species derived from a non-caring ancestor. We investigated the annual and seasonal relationship between green sea turtle (Chelonia mydas) nesting, egg-eating snake population dynamics and density, and predation rates on long-tailed sun skink nests on Orchid Island, to understand the role of this trophic link between terrestrial and marine habitats in the evolution of lizard maternal care

Methods

Results

Conclusion