Behavior of wild vertebrate individuals can vary in response to environmental or social
factors. Such within-individual behavioral variation is often mediated by hormonal …

Largely based on pre-theory that ties high testosterone (T) to masculinity, and low T to
femininity, high T is mainly studied in relation to aggression, mating, sexuality, and …

Life history theory seeks to explain the evolution of the major features of life cycles by
analyzing the ecological factors that shape age-specific schedules of growth, reproduction …

The steroid hormone testosterone has been associated with behavior intended to obtain or
maintain high social status. Although such behavior is typically characterized as aggressive …

Considerable evidence suggests that the steroid hormone testosterone mediates major life-
history trade-offs in vertebrates, promoting mating effort at the expense of parenting effort or …

For male vertebrates, androgens are considered physiological mediators of the trade-off
between mating and parenting effort. About 30 years ago, the challenge hypothesis …

Research on the diversity, evolution and stability of cooperative behaviour has generated a
considerable body of work. As concepts simplify the real world, theoretical solutions are …

In male song sparrows (Melospiza melodia), territorial challenges during the breeding
season can rapidly increase circulating levels of testosterone (T). During the non-breeding …

Variation in male testosterone levels across and within species is known to be related to
mating systems, male dominance rank and aggression rates. When aggression enhances …

Testosterone is a key hormone for the development of secondary sexual characters and
dimorphisms in behavior and morphology of male vertebrates. Because females often …