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The evolution of alternative male phenotypes is probably driven by male-male competition for access to reproductive females, but few studies have examined whether whole-organism performance capacities differ between male morphs, and if so whether any such differences affect fighting ability. We show how ontogenetic changes in performance and morphology have(More)
Differences between sexes in physiological performance have received little attention in animals. We tested for sex differences in maximum sprint speed and maximal exertion over a range of temperatures in a population of Platysaurus intermedius wilhelmi lizards. We also examined sex-based differences in selected temperature range, mean field body(More)
Despite the empirical and theoretical attention paid to the role of sexual signals in resolving agonistic interactions between conspecific males, few studies have applied a comparative perspective, particularly across species that vary in combat intensity. We investigated the relative roles of a male sexual signal (dewlap size) and whole-organism(More)
The evolutionary processes that result in reliable links between male signals and fighting capacity have received a great deal of attention, but the proximate mechanisms underlying such connections remain understudied. We studied a large sample of male green anole lizards (Anolis carolinensis) to determine whether testosterone or corticosterone predicted(More)
Evolutionary theories of aging predict that fitness-related traits, including reproductive performance, will senesce because the strength of selection declines with age. Sexual selection theory predicts, however, that male reproductive performance (especially sexual advertisement) will increase with age. In both bodies of theory, diet should mediate(More)
Males and females from several animal taxa differ in locomotor performance traits such as sprinting and jumping. These performance dimorphisms may be explained at least partially by sexual differences in physiology or morphology. In ectotherms such as reptiles, however, thermal ecology places an additional constraint on realized locomotor performance. I(More)
Sexual signals are considered costly to produce and maintain under the handicap paradigm, and the reliability of signals is in turn thought to be maintained by these costs. Although previous studies have investigated the costly nature of signal production, few have considered whether honesty might be maintained not by the costliness of the signal itself,(More)
Individual quality has been measured as a variety of different traits and in several different contexts. However, the implications of such measurements in terms of overall fitness are less straightforward than has generally been appreciated. Here we outline some key issues in this regard that have yet to be addressed. Specifically, we consider the(More)
Age-specific forced polymorphism is the presence of two or more distinct phenotypes (here we consider only males) that occur in separate sexually mature age groups (e.g., horns in older males but not younger males). The life-stage morph maturation hypothesis posits that all younger males that possess a particular structure can transform into older males(More)
Circulating plasma levels of testosterone often differ among social classes of sexually mature males within a population, but the general physiological mechanisms underlying such differences remain unclear. Within sexually mature male green anole lizards (Anolis carolinensis), smaller "lightweight" males have on average relatively smaller heads, lower(More)