g. Geist, 1966; Jarman, 1983). Clearly, more quantitative analyses of this variation in exaggerated structures are needed before general conclusions
can be made with confidence. Nevertheless, data currently available strongly support a sexual selection function for these traits. In sum, we agree with Padian & Horner that pluralistic explanations are likely necessary for a full functional understanding of exaggerated, or ‘bizarre’, structures in dinosaurs. Species recognition is by no means unlikely as a secondary function for some of these structures, but their large and costly nature coupled with their high variability within species indicates strongly that their primary function involved mate competition, either as weaponry used in intrasexual agonistic behaviours, or as ornaments used in selleck Selleck GS1101 intra- and intersexual interactions. “
“Shrinkage in body length, followed by growth, has rarely been
documented in vertebrates and has been associated with stressful energetic and environmental conditions. Here, we document reversible shrinkage in an amphibian for the first time. Jollyville Plateau salamanders Eurycea tonkawae are neotenic (attain maturity while retaining an aquatic larval form) and inhabit springs and caves of a dissected aquifer in Travis County, TX, USA. We conducted mark-recapture surveys on a spring-dwelling population before and after an exceptional drought in 2008. Use of unique marks and digital photographs of individuals provided precise information on salamander growth rates during and after a period in which salamanders retreated to underground refugia to avoid
desiccation during the drought. Tail width decreased significantly during the drought indicating a reduction in energy stores, a consequence of stressful environmental selleck screening library conditions. Unexpectedly, body length shrinkage also occurred during the drought and was followed by positive growth when spring flow resumed. Body length shrinkage could be an adaptation to coping with long periods of low food availability although its long-term effects are unknown. Given the influence of body size on many ecological and physiological characteristics of organisms, plasticity in body size may have important consequences that go undetected by researchers if shrinkage is ignored. “
“Foraging behaviour plays a key role in growth, survival and reproduction. Male ungulates in temperate environments show seasonal fluctuations in uptake and use of energy, with summer accumulation of reserves later used to sustain the costs of the mating season. To date, however, very little information is available on the foraging behaviour of individuals adopting alternative reproductive tactics.