Parental provisioning behaviour plays a key role in linking personality with reproductive success

A Mutzel,N J Dingemanse,Y G Araya-Ajoy,B Kempenaers

doi:10.1098/rspb.2013.1019

Abstract

Repeatable behavioural traits (‘personality’) have been shown to covary with fitness, but it remains poorly understood how such behaviour–fitness relationships come about. We applied a multivariate approach to reveal the mechanistic pathways by which variation in exploratory and aggressive behaviour is translated into variation in reproductive success in a natural population of blue tits, Cyanistes caeruleus. Using path analysis, we demonstrate a key role for provisioning behaviour in mediating the link between personality and reproductive success (number of fledged offspring). Aggressive males fed their nestlings at lower rates than less aggressive individuals. At the same time, their low parental investment was associated with increased female effort, thereby positively affecting fledgling production. Whereas male exploratory behaviour was unrelated to provisioning behaviour and reproductive success, fast-exploring females fed their offspring at higher rates and initiated breeding earlier, thus increasing reproductive success. Our findings provide strong support for specific mechanistic pathways linking components of behavioural syndromes to reproductive success. Importantly, relationships between behavioural phenotypes and reproductive success were obscured when considering simple bivariate relationships, underlining the importance of adopting multivariate views and statistical tools as path analysis to the study of behavioural evolution.

Highlights

Meta-analyses have revealed that behavioural traits typically show substantial individual repeatability [1], and that individuals from the same population vary in suites of correlated behaviours [2]
Repeatable behavioural traits similar to exploratory tendency or aggressiveness covary with proxies for fitness such as survival [14,15,16] or reproductive success [12,16,17,18,19], implying that behavioural phenotypes are subject to natural selection
Our insight in how behavioural phenotypes affect fitness is still limited because most studies to date have estimated fitness effects of single components of syndromes, e.g. only exploratory behaviour [14,18] or only aggressiveness [20], rather than asking which components of behavioural & 2013 The Authors

Summary

Introduction

Meta-analyses have revealed that behavioural traits typically show substantial individual repeatability [1], and that individuals from the same population vary in suites of correlated behaviours [2]. The repeatability of exploratory behaviour and feeding rate has been demonstrated before [45,47], it has not yet been quantified for our population nor for our specific exploration test Repeatability of both behavioural traits was calculated using univariate mixed-effect models fitted in the MCMCglmm package [48] of R v. Path analysis [51] was applied to infer how proxies for short-term fitness were directly versus indirectly related to behavioural traits (i.e. aggression and exploration), parental investment ( provisioning rate) and female reproductive decisions (lay date and clutch size). Variances and covariances were derived by fitting two multivariate models (MCMCglmm package; see electronic supplementary material, text S4 for details on prior specifications), one for each sex, with aggression (males only), exploratory behaviour, lay date, brood size, the focal individual’s and partner’s feeding rate, and fledging number and weight as response variables (see the electronic supplementary material, tables S2 and S3). As paths between the variables were hypothesized a priori, we present the results for the full model, which includes the paths not supported by the model [55,56]

Results

Discussion

Findings

Conclusions