How accurately do behavioural observations predict reproductive success in free-ranging lizards?

Mats Olsson,Richard Shine,Erik Wapstra,Tonia S Schwartz

doi:10.1098/rsbl.2019.0030

Abstract

Behavioural ecologists often use data on patterns of male–female association to infer reproductive success of free-ranging animals. For example, a male seen with several females during the mating season is predicted to father more offspring than a male not seen with any females. We explored the putative correlation between this behaviour and actual paternity (as revealed by microsatellite data) from a long-term study on sand lizards (Lacerta agilis), including behavioural observations of 574 adult males and 289 adult females, and paternity assignment of more than 2500 offspring during 1998–2007. The number of males that contributed paternity to a female's clutch was correlated with the number of males seen accompanying her in the field, but not with the number of copulation scars on her body. The number of females that a male accompanied in the field predicted the number of females with whom he fathered offspring, and his annual reproductive success (number of progeny). Although behavioural data explained less than one-third of total variance in reproductive success, our analysis supports the utility of behavioural-ecology studies for predicting paternity in free-ranging reptiles.

Highlights

To test ideas about the adaptive significance of mating systems, we need to measure the impact of behavioural variation on individual fitness
We explored the putative correlation between this behaviour and actual paternity from a long-term study on sand lizards (Lacerta agilis), including behavioural observations of 574 adult males and 289 adult females, and paternity assignment of more than 2500 offspring during 1998–2007
Behavioural data explained less than one-third of total variance in reproductive success, our analysis supports the utility of behavioural-ecology studies for predicting paternity in free-ranging reptiles

Summary

Introduction

To test ideas about the adaptive significance of mating systems, we need to measure the impact of behavioural variation on individual fitness. Molecular methods to establish paternity have been used to clarify mating systems of an increasing number of reptilian taxa [5,6,7,8,9], but few studies have gathered the data needed to compare male behaviour with paternity. We have such data for a population of lizards, and the present paper compares behaviourally based indicators of male reproductive success with measures based on molecular analysis of paternity for more than 2500 hatchlings. License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited

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