Environmental variability and acoustic signals: a multi-level approach in songbirds

Abstract

These authors contributed equally to this work.Among songbirds, growing evidence suggests that acoustic adaptation of song traits occurs in response to habitat features. Despite extensive study, most research supporting acoustic adaptation has only considered acoustic traits averaged for species or populations, overlooking intraindividual variation of song traits, which may facilitate effective communication in heterogeneous and variable environments. Fewer studies have explicitly incorporated sexual selection, which, if strong, may favour variation across environments. Here, we evaluate the prevalence of acoustic adaptation among 44 species of songbirds by determining how environmental variability and sexual selection intensity are associated with song variability (intraindividual and intraspecific) and short-term song complexity. We show that variability in precipitation can explain short-term song complexity among taxonomically diverse songbirds, and that precipitation seasonality and the intensity of sexual selection are related to intraindividual song variation. Our results link song complexity to environmental variability, something previously found for mockingbirds (Family Mimidae). Perhaps more importantly, our results illustrate that individual variation in song traits may be shaped by both environmental variability and strength of sexual selection.

The relationship between latitude, migration and the evolution of bird song complexity

“…While many studies do attempt to take the environment into account in some way (such as by classifying them as 'boreal' vs. 'tropical' forest or 'open' vs. 'closed' species), only two studies included here actually measured the habitat and acoustic features at their study sites (Irwin 2000, Singh & Price 2015, and another three used mean climate measures (Botero et al 2009, Medina & Francis 2012, Xing et al 2017. Fully to test the ecological hypotheses included in this review the field requires more studies that explicitly quantify the sound space available at varying latitudes and to determine whether more complex songs fill a wider swathe of that space.…”

Distinct song parts of the endemic marsh grassbird of China vary with latitude and climate among migratory and sedentary populations

“…Consequently, the marsh grassbird contributes another case of contradictory patterns to the literature and confirms that there are no simple explanations or clear general patterns (c.f. Byers 2011Byers , 2015Medina and Francis 2012).…”

“…Several comparative studies have confirmed positive correlations between song elaboration and latitude, both among (Catchpole 1982;Botero et al 2009) and within species (Collins et al 2009;Kaluthota et al 2016). However, there are also studies with contrasting results (Byers 2011(Byers , 2015Medina and Francis 2012) and more studies are needed for a better understanding.…”

“…We included rainfall and temperature, which are well-known to affect migratory behaviour (Salewski and Bruderer 2007;Louchart 2008;Zink 2011) and possibly song structure (e.g. Botero et al 2009;Weir and Wheatcroft 2011;Medina and Francis 2012). We explored whether the acoustic variation within songs and across latitude and climate was in line with expectations for divergent functions of the different song parts.…”

Loss of sexual dimorphism is associated with loss of lekking behavior in the green manakinXenopipo holochora

“…Although sexual dimorphism may arise as the result of natural selection (Shine 1989, Badyaev andHill 2003), sexual selection is frequently invoked as the main force driving these differences (Darwin 1871, Andersson 1994. In fact, degree of sexual dimorphism is a commonly used indicator of sexual selection intensity (Owens et al 1999, Nadeau et al 2007, Medina and Francis 2012, an assumption generally supported by correlations between sexual dimorphism and intensity of sperm competition (Bennett and Owens 2002), rate of evolution of genes involved in plumage coloration (Nadeau et al 2007), or degree of polygyny (Payne 1984, Dunn et al 2001; but see Burns 1998, Friedman et al 2009). …”