Why male animals from far-off areas beget less offsprings

If male animals travelling long distances are unable to woo females in an entirely unknown group, mating chances can decrease significantly for them, say researchers including an Indian-origin scientist, highlighting current gaps in the understanding of animal dispersal.

The team examined the mating dynamics of transient wildlife that have dispersed from other areas. They link these results to existing evidence showing that males from far-off areas have less offsprings.

"What happens to a disperser after it enters a new population is unknown," said lead author Divya Vasudev from the Wildlife Conservation Society in the US.

The scientists who relied on an Individual-based simulation model of animal dispersal said that the results would help inform the siting of wildlife corridors, translocating animals and other conservation interventions.

Their simulation model, based on data from chimpanzees, is generally applicable to a wide range of species, including many endangered carnivores, primates, other mammals and birds.

Lack of attractiveness to potential mates, the authors found, in these "dispersers" can ultimately reduce landscape connectivity.

The authors modelled mate choice and dispersal in animals across multiple generations.

They showed that even when animals dispersed freely through contiguous habitats, mate choice alone could lead to habitat fragmentation and isolated populations if females avoided mating with dispersers.

The physical toll of moving across large, inhospitable landscapes can make dispersers unattractive as potential mates.

"Also, females may look for a degree of familiarity in mates. For populations that have adapted to local conditions, familiarity relates directly to survivability," the authors noted.

On the other hand, due to inbreeding and associated costs of mating with close relatives, females may actually prefer mating with dispersers. "Ultimately, better conservation will depend on better understanding of real connectivity in fragmented landscapes," Vasudev added.