Sensory biases in response to novel complex acoustic signals in male and female grey treefrogs, Hyla chrysoscelis

Abstract

The sensory bias hypothesis proposes that female preferences for male sexual signalling traits evolved in contexts other than mating. Individuals of both sexes may experience similar selection pressures in these contexts; thus males may have similar biases to females for variation in signal traits. We tested this prediction in the grey treefrog, Hyla chrysoscelis , in which males produce simple advertisement calls, but females are more attracted to certain novel complex stimuli. We recorded males' responses to playbacks of both simple advertisement calls and complex calls consisting of the advertisement call with an acoustic appendage (filtered noise, or heterospecific call pulses) either leading or following the call. We tested females’ preferences for the same stimuli in phonotaxis tests. We found evidence for a sensory bias in both sexes: males gave more aggressive calls in response to complex stimuli and females sometimes preferred complex over simple calls. These biases were not universal and depended on both temporal order and appendage characteristics, but how these effects manifested differed between the sexes. Ultimately, our approach of studying biases of both sexes in response to novel mating signals will shed light on the origin of mating preferences, and the mechanisms by which sensory biases operate.

Image Processing of Thigh Color Pattern Is an Effective Method for Identifying Individual Cope's Gray Treefrogs, Hyla chrysoscelis

“…All procedures followed the ASIH Guidelines for Live Amphibians and Reptiles in Field and Laboratory Research and were approved by the Institutional Animal Care and Use Committee of Oklahoma State University (AS-19-4) and the Oklahoma Department of Wildlife Conservation. Most subjects were male frogs that were captured nightly during the breeding season as part of studies of their acoustic communication behavior (Clapp and Reichert, 2022; Reichert and de la Hera, 2022; Reichert et al, 2022: bioRxiv 2022.10.10 .511667). In 2019, we captured 13 females, which were also included in this study.…”

“…Amphibians are a major focus of conservation efforts because they face many threats including emerging infectious diseases (e.g., chytridiomycosis; Fisher and Garner, 2020) and anthropogenic pressures such as habitat destruction, invasive species, pollutants, and climate change (Collins and Storfer, 2003). In addition, amphibians are model systems for studies of communication and sexual selection (Wells, 1977), and the increased focus on individual variation in these behaviors also requires a method to reliably identify individuals (Reichert et al, 2022: bioRxiv 2022.10.10 .511667).…”

“…Hyla chrysoscelis has been a subject of studies on ecology (Resetarits and Wilbur, 1991), acoustic communication behavior (Gerhardt, 2005), physiology (Zimmerman et al, 2007), and toxicology (Earl and Whiteman, 2010), for which individual identification can be an important aspect of the experimental design. Various marking procedures have been used for H. chrysoscelis , including toe-clipping (Ritke et al, 1991) and VIE (Reichert et al, 2022: bioRxiv 2022.10.10.511667). However, as an indication of the difficulties associated with marking and identifying this species, some studies have not marked individuals at all, taking the assumption that recapture was unlikely given their experimental design (Schrode et al, 2012).…”