Behavioral, morphological, and ecological trait evolution in two clades of New World Sparrows (Aimophila and Peucaea, Passerellidae).

Carla Cicero,James D Rising,Nicholas A Mason,Lauryn Benedict

doi:10.7717/peerj.9249

Abstract

The New World sparrows (Passerellidae) are a large, diverse group of songbirds that vary in morphology, behavior, and ecology. Thus, they are excellent for studying trait evolution in a phylogenetic framework. We examined lability versus conservatism in morphological and behavioral traits in two related clades of sparrows (Aimophila, Peucaea), and assessed whether habitat has played an important role in trait evolution. We first inferred a multi-locus phylogeny which we used to reconstruct ancestral states, and then quantified phylogenetic signal among morphological and behavioral traits in these clades and in New World sparrows more broadly. Behavioral traits have a stronger phylogenetic signal than morphological traits. Specifically, vocal duets and song structure are the most highly conserved traits, and nesting behavior appears to be maintained within clades. Furthermore, we found a strong correlation between open habitat and unpatterned plumage, complex song, and ground nesting. However, even within lineages that share the same habitat type, species vary in nesting, plumage pattern, song complexity, and duetting. Our findings highlight trade-offs between behavior, morphology, and ecology in sparrow diversification.

Highlights

Behavioral, morphological, and ecological traits have been used historically to reconstruct evolutionary relationships, and many taxonomic groups were originally designated on the basis of shared, homologous characters (e.g., Hamilton, 1962; Storer, 1955; Wolf, 1977)
Within the Aimophila and Peucaea clades, we found that complex songs are significantly associated with open grassland habitat, and simple songs are associated with closed habitat
We found that unpatterned plumage correlated with open grassland habitat among members of the Aimophila and Peucaea clades, as well as when trait correlation analyses were run using the full tree

Summary

Introduction

Behavioral, morphological, and ecological traits have been used historically to reconstruct evolutionary relationships, and many taxonomic groups were originally designated on the basis of shared, homologous characters (e.g., Hamilton, 1962; Storer, 1955; Wolf, 1977). Similarities in syringeal and cranial morphology, plumage, nesting behavior, and foraging mode were used to establish generic limits and hypothesize relationships in tyrannid flycatchers, one of the world’s largest and most diverse avian radiations (Lanyon, 1984; Lanyon, 1985; Lanyon, 1986; Lanyon, 1988a; Lanyon, 1988b). Hamilton (1962) inferred species relationships and the origin of sympatry in the avian genus. Behavioral, morphological, and ecological trait evolution in two clades of New World Sparrows (Aimophila and Peucaea, Passerellidae). Vireo by comparing species-specific characteristics of distribution, habitat preference, foraging ecology, and external morphology. While contemporary studies of evolutionary relationships rely largely on genetic data, studies of trait evolution in a phylogenetic framework continue to shed light on patterns of phenotypic evolution and diversification

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