Current research in amphibians: Studies integrating endocrinology, behavior, and neurobiology

Abstract

Amphibian behavioral endocrinology has focused on reproductive social behavior and communication in frogs and newts. Androgens and estrogens are critical for the expression of male and female behavior, respectively, and their effects are relatively clear. Corticosteroids have significant modulatory effects on the behavior of both sexes, as does the peptide neuromodulator arginine vasotocin in males, but their effects and interactions with gonadal steroids are often complex and difficult to understand. Recent work has shown that the gonadal hormones and social behavior are mutually reinforcing: engaging in social interactions increases hormone levels just as increasing hormone levels change behavior. The reciprocal interactions of hormones and behavior, as well as the complex interactions among gonadal steroids, adrenal steroids, and peptide hormones have implications for the maintenance and evolution of natural social behavior, and suggest that a deeper understanding of both endocrine mechanisms and social behavior would arise from field studies or other approaches that combine behavioral endocrinology with behavioral ecology.

Social regulation of plasma estradiol concentration in a female anuran

“…Further, electrophysiological studies indicate that auditory cues stimulate hypothalamic neurons (Cheng et al, 1998). Similar phenomena in which vocal signals from a sender influence the physiology and neurobiology of a receiver have also been described in anuran amphibians Wilczynski et al, 2005). This is possible because in anurans, the central auditory system sends projections into the anterior and central thalamic nuclei, which relay auditory information into the anterior preoptic area as well as the ventral hypothalamus (reviewed in Wilczynski et al, 1993).…”

The use of bioacoustics in anuran taxonomy: theory, terminology, methods and recommendations for best practice

“…Recent findings, however, indicate that relationships between calling activity and energy consumption may be complex (Carvalho et al 2008), emphasizing the need for more comprehensive observations of amphibian traits related to calling activity, such as incorporating not only social context, but also breeding period, locomotor behavior, and calling strategies. Intricately related to these two factors are hormones (Moore et al 2005;Wilczynski et al 2005;). Several studies have suggested that androgens and the neuropeptide arginine vasotocin (AVT) influence the calling behavior of frogs (Emerson & Hess 1996;Solis & Penna 1997;ten Eyck 2005), and higher androgen levels have been found in frogs exposed to conspecific vocalizations (Brzoska & Obert 1980;O'Bryant & Wilczynski 2010).…”

“…The available results from different species are however not fully concordant, especially regarding the relationship of androgen levels and calling behavior (Moore et al 2005;Wells 2007). Evidence is more straightforward suggesting that AVT stimulates calling behavior (reviewed by Wilczynski et al 2005) and, more importantly, that it influences call features such as call patterning, call duration and pulse number (Marler et al 1995;Chu et al 1998;Klomberg & Marler 2000;Trainor et al 2003;Kime et al 2007). Taken together, the available evidence suggests that social interactions, hormones, and energetics are tightly linked to each other in numerous ways, and all of these factors have the potential to influence those features of frog vocalizations that are often considered relevant for taxonomic purposes.…”

Courtship and copulation in the adult male green anole: Effects of season, hormone and female contact on reproductive behavior and morphology

“…In diverse vertebrates, the preoptic area (POA) and amygdala (AMY) are necessary for the production of male-specific courtship and copulatory behaviors [7,26,43,57,62,93,96,97]. Motoneurons located in the brainstem or spinal cord innervate muscles required for courtship and copulatory behaviors.…”