Vocal divergence between two disjunct populations of Giant Antshrike (Batara cinerea) is related to environmental conditions

Abstract

Variation in the avian vocal signals emitted may have a significant impact on species evolution. Vocal divergence in suboscine species like Giant Antshrike (Batara cinerea) may be associated with selective adaptation, since learning has little influence on vocal development and variation in acoustic structure cannot be attributed to learning deviation. Consequently, tracheophone suboscine species are ideal subjects to explore vocal variation, since cultural evolution does not seem to influence vocal variation in this group. Environmental conditions may determine the selection of vocal features because acoustic transmission could be attenuated under certain conditions of temperature, humidity and vegetation cover. Here, we examined vocalizations of Giant Antshrike and assessed possible acoustic variations between two disjunct groups (Andean and Atlantic), correlating the differences to the environmental structure. Univariate and multivariate analysis show temporal and spectral differences between both groups. Andean individuals produce vocalizations with longer duration, faster trill rates, shorter syllable duration and higher frequencies. Environmental features are different between the two populations, and they are correlated to the acoustic structure of vocalizations. Temporal variations arise directly from climatic influence, while spectral divergence could be a secondary effect of morphological adaptation to habitat structure.

Song variation in a Neotropical mountain passerine, the Brown-capped Redstart (Myioborus brunniceps), is predicted by geographic isolation and environmental factors

“…However, maximum green vegetation cover is expected to be very sensitive to variation of vegetation cover (e.g., presence and absence of chlorophyll) but not to type of cover (e.g., grasslands versus bushes), and thus it does not seem to be useful to understand bird song variation in terms of habitat structure. A similar result was found in other studies of birdsong (e.g., Sementili-Cardoso and Donatelli 2019).…”

“…2, Table 2) and because variances of some of its spectral features were similar between isolated and non-isolated populations. Most of the climate metrics associated with song variation of the Brown-capped Redstart have been previously identified as factors to model variation of song and of other avian phenotypic features (Sosa-López et al 2013, Xing et al 2017, Sementili-Cardoso and Donatelli 2019, Sheard et al 2020).…”

Natural Patterns in the Dawn and Dusk Choruses of a Neotropical Songbird in Relation to an Urban Sound Environment

“…The authors found no bias in the frequency parameters but rather a comparatively reduced precision. This low precision appears to have little effect in song frequency comparisons between different species [57], in intraspecific comparisons [58], or when both types of records (MP3 and WAVE) were used together [59,60]. After that, we selected for analysis only clear recordings of songs without other masking sounds, for which their respective SSP and ESP measurements were taken.…”