The costs and benefits of mate choice can vary both spatially and temporally. Phenotypic plasticity in mate choice, which could be due to changes in choice criteria (e.g., acceptance thresholds) or shifts in underlying mating preferences (i.e., relative values assigned to different males), can...

It can be less costly to help a neighbor repel an intruder than to renegotiate boundaries with a new and potentially stronger individual. Male fiddler crabs will help a smaller neighbor fight off an intruder when the intruder is intermediate in size relative to the 2 neighbors. Fights involving...

In many species males that tend to win fights against other males are more attractive to females. There are three ways in which male fighting ability and attractiveness may be associated: (1) attractiveness and fighting ability are influenced by the same underlying traits (e.g., body size), (2)...

Recent studies suggest that males might respond in an adaptive manner to an elevated likelihood of male--male competition for mates by facultatively altering their mating preferences. Little is known, however, about how male choice is influenced by a male's relative competitiveness or by the...

Studies of sexual selection and immunity in invertebrates often assay components of the immune system (e.g., encapsulation response, hemocyte counts) to estimate disease resistance. Because increased disease resistance is thought to enhance fitness in most cases, we might expect a positive...

Males of many species defend resources to attract females. Surprisingly, defense of multiple female breeding sites (e.g., nests or burrows) appears to be rare, primarily reported in fish and birds. In fiddler crabs, burrows are a vital resource for reproduction and survival. Both sexes defend...

Flight distance reflects the risk that an individual animal is willing to take when approached by a potential predator. Because residual reproductive value is the average number of offspring that an individual of a given age class is expected to produce after the current reproductive event,...

Urbanization and domestication share features in terms of characters that are favored by selection. These include loss of fear of humans, reduced corticosterone levels, prolonged breeding seasons, and several others. Here, I test the hypothesis that urbanization results from differential...

Investigations of avian influenza have so far focused on the global circulation and conversion of virus strains and showed that wild waterfowl and especially ducks represent the reservoir and source of virus strains that can become highly pathogenic in domestic species. Information is largely...