Testosterone secretion varies in a sex- and stage-specific manner: Insights on the regulation of competitive traits from a sex-role reversed species.

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Testosterone (T) mediates a variety of traits that function in competition for mates, including territorial aggression, ornaments, armaments, and gametogenesis. The link between T and mating competition has been studied mainly in males, but females also face selection pressures to compete for mates. Sex-role reversed species, in which females are the more competitive sex, provide a unique perspective on the role of T in promoting competitive traits. Here, we examine patterns of T secretion in sex-role reversed northern jacanas (Jacana spinosa) during breeding, when females are fertile and males are either seeking copulations or conducting parental care. We measured baseline levels of T in circulation along with a suite of behavioral and morphological traits putatively involved in mating competition. We evaluated hypotheses that levels of T track gonadal sex and parental role, and we begin to investigate whether T and competitive traits co-vary in a sex- and stage- specific manner. Although females had higher expression of competitive traits than males at either breeding stage, we found that females and incubating males had similar levels of T secretion, which were lower than those observed in copulating males. T was correlated with wing spur length in females and testes mass in copulating males, but was otherwise uncorrelated with other competitive traits. These findings suggest that levels of T in circulation alone do not predict variation in competitive traits across levels of analysis, including gonadal sex and parental role. Instead, our findings coupled with prior research indicate that selection for female mating competition and male care may generate different physiological regulation of competitive traits.





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Lipshutz, Sara E, and Kimberly A Rosvall (2020). Testosterone secretion varies in a sex- and stage-specific manner: Insights on the regulation of competitive traits from a sex-role reversed species. General and comparative endocrinology, 292. p. 113444. 10.1016/j.ygcen.2020.113444 Retrieved from https://hdl.handle.net/10161/28957.

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Sara E Lipshutz

Assistant Professor of Biology

Our research focuses on the evolution of behavior across weird and wonderfully diverse species of birds. This work bridges “muddy boots” experimental fieldwork with a variety of molecular and computational approaches in genetics, genomics, neuroscience, and endocrinology. We have several research foci:  


1. Female perspectives in biology. Cultural biases shape our predictions for how and why animals behave the way they do, and female animals have historically been neglected in biological research. We study the evolution of female competition across diverse avian species, ranging from social polyandry to monogamy in shorebirds and songbirds. Critically, hypotheses derived from studying males (i.e. testosterone focus) do not explain interspecific variation in female aggression. We use population genomic and transcriptomic data to evaluate the proximate causes and ultimate consequences of female competition.  


2. Global change biology. In the age of the Anthropocene, animals are facing evolutionary unprecedented environmental changes. Sensory pollutants like anthropogenic noise and artificial light at night can alter animal physiology, behavior, and ecology on a rapid timescale. Behavior flexibility and adaptation may lead the way in helping animals respond to novel challenges. We investigate why some individuals and species may be better prepared to face global change.  

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