Researchers have discovered that chimpanzees actively choose mates who are genetically dissimilar. This behavior may help the apes avoid inbreeding, which would negatively affect their offspring. The details are in a paper that was just published in the journal Royal Society Open Science.
Inbreeding can be a serious problem for animal populations and a lack of genetic diversity can lead to extinction. When animals with similar genomes reproduce, they’re more likely to pass on deadly mutations. Most serious mutations are caused by a recessive allele that can be balanced out by the other parents’ version of the gene. When two animals are related, however, their offspring are likely to get two copies of the bad allele—leading to serious health problems. Populations with low genetic diversity are also less likely to adapt to changes in their environment, including sudden epidemics.
A team of researchers studied wild chimpanzees (Pan troglodytes) living in in Gombe National Park. The team conducted genomic analyses of 153 individuals, both male and female. The data could be used to determine which chimpanzees were genetically similar. The researchers then observed breeding events, recording the pairings that resulted in offspring.
The research team found that the chimpanzees were mating with individuals who were genetically dissimilar—at least when it came to matings that led to reproduction. This was especially true for immigrant females, who appeared to seek out the most nonrelated males even when they didn’t live among any close relatives. In chimpanzee populations, females often move out of their communities when they reach breeding age. Yet these chimps showed a stronger preference for genetically dissimilar males when compared to non-immigrant females. The team isn’t sure how the chimpanzees can tell but current theories include scent and general appearance.
The team’s findings show that chimpanzees appear to actively seek out genetically unrelated mates when they’re ready to reproduce. Further research may reveal how they manage to identify which chimpanzees are unrelated.
Walker et al. Chimpanzees breed with genetically dissimilar mates. Royal Society Open Science (2017).