Ecological drivers of song evolution in birds: Disentangling the effects of habitat and morphology.

Elizabeth Perrault Derryberry,Robb Thomas Brumfield,Santiago Claramunt,Glenn Fairbanks Seeholzer,Joseph Andrew Tobias,Graham Earnest Derryberry,Nathalie Seddon

doi:10.1002/ece3.3760

Abstract

Environmental differences influence the evolutionary divergence of mating signals through selection acting either directly on signal transmission (“sensory drive”) or because morphological adaptation to different foraging niches causes divergence in “magic traits” associated with signal production, thus indirectly driving signal evolution. Sensory drive and magic traits both contribute to variation in signal structure, yet we have limited understanding of the relative role of these direct and indirect processes during signal evolution. Using phylogenetic analyses across 276 species of ovenbirds (Aves: Furnariidae), we compared the extent to which song evolution was related to the direct influence of habitat characteristics and the indirect effect of body size and beak size, two potential magic traits in birds. We find that indirect ecological selection, via diversification in putative magic traits, explains variation in temporal, spectral, and performance features of song. Body size influences song frequency, whereas beak size limits temporal and performance components of song. In comparison, direct ecological selection has weaker and more limited effects on song structure. Our results illustrate the importance of considering multiple deterministic processes in the evolution of mating signals.

Highlights

Differences in mating signals among related lineages have important functional consequences for mate choice and species recognition (Coyne & Orr, 2004; Mayr, 1963)
We found strong evidence that additive models of morphology and habitat explained variation in minimum frequency, with Habitat garnering 80% of the total weight of candidate models
We find that spectral features of song vary with body size, and any association with habitat is not consistent with predictions under sensory drive

Summary

| INTRODUCTION

Differences in mating signals among related lineages have important functional consequences for mate choice and species recognition (Coyne & Orr, 2004; Mayr, 1963). Ecological selection can influence mating signals indirectly by causing divergence in traits related to signal production and modification (Endler, 1993), such as body size (Gil & Gahr, 2002) and beak size (Podos & Nowicki, 2004b) in birds. We use phylogenetic comparative techniques to assess the relative roles of direct and indirect ecological selection on song diversification across 285 species of ovenbirds (Furnariidae), a diverse clade with comprehensive data on phylogenetic relationships, morphology, and song (Derryberry et al, 2012; Tobias et al, 2014). Morphology, and phylogenetic relationships allowed us to test the relative influence of sensory drive and magic traits against this stochastic null model

| MATERIALS AND METHODS

| DISCUSSION

Findings

| CONCLUSIONS

CONFLICT OF INTEREST