Abstract
Some animal vocalizations develop reliably in the absence of relevant experience, but an intriguing subset of animal vocalizations is learned: they require acoustic models during ontogeny in order to develop, and the learner's vocal output reflects those models. To what extent do such learned vocalizations reflect phylogeny? We compared the degree to which phylogenetic signal is present in vocal signals from a wide taxonomic range of birds, including both vocal learners (songbirds) and vocal non-learners. We used publically available molecular phylogenies and developed methods to analyse spectral and temporal features in a carefully curated collection of high-quality recordings of bird songs and bird calls, to yield acoustic distance measures. Our methods were initially developed using pairs of closely related North American and European bird species, and then applied to a non-overlapping random stratified sample of European birds. We found strong similarity in acoustic and genetic distances, which manifested itself as a significant phylogenetic signal, in both samples. In songbirds, both learned song and (mostly) unlearned calls allowed reconstruction of phylogenetic trees nearly isomorphic to the phylogenetic trees derived from genetic analysis. We conclude that phylogeny and inheritance constrain vocal structure to a surprising degree, even in learned birdsong.This article is part of the theme issue ‘Vocal learning in animals and humans’.
Highlights
The fact that closely related species resemble one another in form is a fundamental insight in evolutionary biology [1,2,3], and the realization that the same is often true of behavioural patterns was foundational in the development of ethology [4,5,6]
The authors found clear evidence of preserved phylogenetic signal in this clade, even when controlling for habitat type and two morphological characteristics. They concluded that acoustic parameters of these neotropical parrots are highly conserved across evolution, despite clear evidence for vocal learning. These previous studies strongly suggest that phylogenetic signal can persist in avian vocalizations, whether or not the clade consists of vocal learning species
Summarizing, in a large set of avian vocalizations including 71 songbird and 66 non-songbird species, using multiple measures, our results show that strong phylogenetic signal is present in vocally learned birdsong, as well as songbird calls and non-passerine display vocalizations presumed to be unlearned
Summary
The fact that closely related species resemble one another in form is a fundamental insight in evolutionary biology [1,2,3], and the realization that the same is often true of behavioural patterns was foundational in the development of ethology [4,5,6]. Vocalizations produced by a given species reflect both vocal anatomy and behaviour, each of which may have strong heritable components. This suggests that homologous vocalizations of closely related species may resemble each other more than pairs drawn at random—in other words that vocalizations may possess ‘phylogenetic signal’. Much previous work has focused on calls with a strong innate basis, raising the question of whether phylogenetic signal persists in vocalizations with a strong learned component. To the extent that learned vocalizations reflect inherited constraints imposed by species-typical motor circuitry or vocal anatomy, and/or biases in the learning mechanism itself, they might still possess phylogenetic signal, even if at reduced levels. B 376: 20200241 species selection vocalizations acoustic features acoustic distance matrix songbirds non-songbirds
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Schedule a callMore From: Philosophical transactions of the Royal Society of London. Series B, Biological sciences
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