Chemical communication in a declining North American anuran amphibian, the northern leopard frog (lithobates pipiens)

Chemical signaling is known to be an important communication mechanism for amphibians. However, very few studies have directly investigated chemical signaling in anuran groups (frogs and toads), particularly adult anurans. Previous work has focused primarily on salamander and larval anuran behavioral responses. Additionally, chemoreceptor (CR) genes have only been identified for Xenopus species with no previous identifications for any other adult anuran species. Here, I examine the evolutionary and functional implications of northern leopard frog (Lithobates pipiens) CRs, identified through collaboration, by conducting a phylogenetic analysis for each CR type identified using a Maximum Likelihood approach (Chapter 1). I incorporated amino acid CR sequences spanning aquatic, semiaquatic, and terrestrial vertebrate species, and the resulting trees indicate split divergence patterns across CR types. More specifically, olfactory receptors (ORs) and trace amine associated receptors (TAARs) appear to be most closely related to transitional vertebrate and terrestrial species’ orthologs, and vomeronasal receptors (VRs Types I and II) appear to be most closely related to transitional vertebrate and aquatic vertebrate orthologs, hinting at both volatile and aquatic (water soluble and nonvolatile) detection of chemicals. In this study, I also investigate terrestrial, sex-biased anuran behavioral responses to conspecific chemical cues in adult L. pipiens, comparing time spent on cue and non-cue sides of an experimental terrarium (Chapter 2) to expand on current knowledge of chemical detection in a declining, North American species. Results show nuanced response profiles for males and females, based on familiarity (odors of individuals housed together and those that were housed in separate enclosures) and same-sex vs. opposite-sex cues. Females were more responsive overall (P