Meeting Abstract
All behavior requires energy, but the costs of behavior are particularly conspicuous in the context of animal communication. Animals must invest not only to stand out against a noisy environment, but also to pay the costs of behaviors that follow from communication displays. Much of what we know about the regulation of energy balance, however, comes from rodent models that lack elaborate signals. We develop Alston’s singing mouse, Scotinomys teguina – a small diurnal species living in the cloud-forests of Central America – as a model for investigating the relationship between body condition and display effort. We first asked in which dimensions condition varies between male mice, examining a range of circulating nutrients including plasma fatty acids and glucose, metabolic hormones (insulin, adiponectin, leptin), and residual body mass (RBM). Next we asked about the dimensions of variation in male song, examining the number of songs, latency to sing, length of songs, and a variety of measures of amplitude and frequency modulation. Lastly, we asked how well dimensions of condition correlated with dimensions of song effort. We found that measures of adiposity (hormones, RBM) tended to vary independently of circulating nutrients. We found that songs of singing mice differ both in frequency signatures and in “song effort”—measures of temporality and amplitude. We found evidence that song effort is condition-dependent in singing mice. While RBM weakly predicted song effort, adiposity signals (particularly leptin) greatly improved our model. Thus male singing mice seem to adjust song effort as a function of variation in body condition in the field. Refining our understanding of this relationship will allow us to better understand the neuroendocrine mechanisms regulating display effort, and the integrative understanding of animal communication.
