Nonadditive effects of group membership are generated when individuals respond differently to the same social environment and may alter predictions about how behavioural evolution will occur. Despite this importance, the relationship between an individual's behaviour in two different social contexts and how reciprocal interactions among individuals within groups influence group behaviour are po...

Most studies of repeatability examine female mate choice, but male mate choice may have significant evolutionary consequences when males of a sexual species are sexually parasitized by heterospecific gynogenetic females as is the case for sailfin mollies, Poecilia latipinna. Amazon mollies, Poecilia formosa, are all female gynogens that require sperm from P. latipinna for initiation of embryoge...

Predation and parasitism are two of the most important sources of mortality in nature. By forming groups, individuals can gain protection against predators but may increase their risk of being infected with contagious parasites. Animals might resolve this conflict by forming mixed-species groups thereby reducing the costs associated with parasites through a relative decrease in available hosts....

ŽAnimals colonizing lightless subterranean habitats can no longer rely on visual signals to find mating partners. In the present study, we investigated the ability of males to recognize females in two surface and a cave dwelling population of a livebearing fish, Poecilia mexicana. In surface populations males discriminated between sexes with visual plus non-visual cues available and with visual...