Male guppies spend most of their time displaying their brightly-coloured bodies to females in the hope of attracting a mate. The choosy females will usually only mate with the most attractive, high-quality males to ensure the production of strong offspring. If his courtship display is rejected, the male will often attempt to sneak a mating with his chosen female when she is not looking. Avoiding the relentless male harassment uses up precious resources such as time and energy. This in turn reduces the time available for food foraging, and energy for growth and reproduction.

The researchers studied guppy behaviour in a Trinidad river and found that the females are segregating the sexes by choosing to spend time in areas where there are high numbers of predators. The brightly-coloured males are far more likely to attract the predators than the dull brown females, so they keep their distance.

Dr Croft explains, “Much like humans, female guppies produce relatively few eggs and give birth to live offspring. They don’t lay their eggs for a seasonal spawning but keep them inside their bodies where they are fertilised by the males. Because they are not reliant on seasons, the females have a continuous battle to keep the males at bay – so they are resorting to extreme measures to avoid unwelcome attention.”

This work was funded by the Natural Environment Research Council.

Story Source:

Materials provided by Natural Environment Research Council (NERC). Note: Content may be edited for style and length.

Journal Reference:

1. Darden et al. Male harassment drives females to alter habitat use and leads to segregation of the sexes. Biology Letters, 2008; 1 (-1): -1 DOI: 10.1098/rsbl.2008.0308