Sex-biased movement in the guppy ( Poecilia reticulata )

Abstract

The movement strategies of birds and mammals are often closely linked to their mating system, but few studies have examined the relationship between mating systems and movement in fishes. We examined the movement patterns of the guppy ( Poecilia reticulata) in the Arima river of Trinidad and predicted that sexual asymmetry in reproductive investment would result in male-biased movement. Since male guppies maximize their reproductive success by mating with as many different females as possible, there should be strong selection for males to move in search of mates. In agreement with our prediction, the percentage of fish that emigrated from release pools was higher for males than females (27.3% vs. 6.9%, respectively). Sex ratio was highly variable among pools and may influence a male's decision to emigrate or continue moving. We also detected a positive relationship between body length and the probability of emigration for males and a significant bias for upstream movement by males. Among the few females that did emigrate, a positive correlation was observed between body length and distance moved. Sex-biased movement appears to be related to mating systems in fishes, but the evidence is very limited. Given the implications for ecology, evolution, and conservation, future studies should explicitly address the influence of sex and mating systems on movement patterns.

Environmental and genetic influences on mating strategies along a replicated food availability gradient in guppies (Poecilia reticulata)

“…We found three independent components of variation in male behavior in the field: (1) courtship versus foraging, (2) dominance interactions, and (3) interference competition versus searching for mates (Table 1; also see Croft et al 2003). Each of these behavioral components varied among sites but only the third correlated with food availability in the field.…”

“…We commonly observed aggression in the context of mating in the field at sites ranging from small, isolated pools with high guppy densities to larger streams with fastflowing currents and low guppy densities. Although males move among pools (Croft et al 2003), we sometimes resighted males on multiple visits. At the Marianne Tributary (see Fig.…”

Upstream guppies (Poecilia reticulata, Peters, 1859) go against the flow

“…This could explain why the UN guppies show the highest level of rheotaxis. Croft et al (2003) showed sex-biased dispersal in guppies, demonstrating a significant bias for upstream movement by males but not females. In addition, they found a positive correlation between body length and distance moved in females.…”

Male harassment drives females to alter habitat use and leads to segregation of the sexes

“…A total of 240 fish (120 large females (29.9G0.2 mm), 60 males (21.2G0.2 mm) and 60 small females (22.1G0.2 mm)) were individually marked with implant elastomer (see Croft et al 2003 for details) and tested in the enclosures in the mixed-or same-sex groups of 10 individuals across the study period. In the same-sex groups, small females were matched to the size of the males in the mixed-sex groups.…”