Social Mongooses Synchronize Births to Avoid Infanticide
Some social mammals like mongooses may have evolved to give birth at the same time to reduce infanticide.
Infanticide happens when animals "police" selfish reproduction by killing the offspring of subordinate animals. For instance eggs laid by worker honeybees are identified and killed out by the rest of the workforce.
Scientists wanted to find out whether policing" can explain patterns of reproduction of the banded mongoose (Mungos mungo). Banded mongooses are very social mammals that have groups that contain 1 - 12 female breeders who give birth to a communal litter. They are interesting because the female breeders typically give birth on the same day.
Professor Michael Cant of Biosciences at the University of Exeter and colleagues studied 11 groups of wild banded mongooses for seven years. Researchers manipulated which females contributed offspring to the communal litter using short-acting contraceptives.
The findings revealed that dominant females kill entire litters if they had not given birth. However, they allow the communal litter to live if their is a chance that it contains their own offspring.
Researchers said the study supports the belief that policing plays an important role in the evolution of cooperation among vertebrates, and shows that threats of infanticide can lead to remarkable counterstrategies to avoid reproductive control.
"Unlike meerkats and other cooperative mammals in which there is usually a single dominant female breeder in each group, in banded mongooses up to 12 females can become pregnant and synchronise birth to the same day. Our experiment suggests that this remarkable feat of coordination is actually driven by intense conflict over reproduction. Females synchronise birth to the same day because this confuses maternity in the communal litter, so any infanticidal female might end up killing her own young," Cant said in a news release.