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Animal Antics: Lemur incest avoided through voice recognition

By MELANIE HSU | December 6, 2012

Imagine growing up without your father. Now imagine that you are a small primate living in the dense jungles of Madagascar. If you were to run into your dad 15 years later, would you be able to pick out his voice from the other sounds in the jungle?

Despite being solitary animals, lemurs have the uncanny ability to recognize their dads’ cries. The study, led by Sharon Kessler and colleagues at the University of Veterinary Medicine in Hanover, Germany, is the first to show that solitary animals may avoid inbreeding by tuning in to familiar voices.

Previous research has shown that animals living in complex social groups are adept at recognizing kin calls, especially the sounds of maternal relatives. For example, a study conducted back in June reported that mother goats can recall their babies’ bleats for at least one year after they are separated, indicating that their memory of familial ties are long-term.

Even more impressive are tamarin monkeys, which can recall their relatives’ calls for up to four years after separation. Similar results have been reported in many other mammals, including seals, monkeys, squirrels and elephants. Clearly, these animals place much value on family time.

On the contrary, little is known about how animals recognize paternal calls and vocalizations of relatives on the father’s side of the family. Moreover, researchers know little about how solitary animals avoid combining their rare recessive alleles with those of from dad’s side of the family.

This particular lapse in knowledge was addressed in a study on the gray mouse lemur, Microcebus murinus. These arboreal acrobats are found leaping from branch to branch in the treetops of Madagascar’s forests, occasionally descending on the ground to forage.

As their name probably suggests, these lemurs are among the smallest of primates, ranging from 10 to 14 c.m. in height. Cartoonishly cute in appearance, baby lemurs are raised solely by their mothers.

When gray mouse lemurs reach adulthood, they leave the nest to forage on their own. However, male lemurs have large ranges that often overlap with that of their daughters, presenting conditions where evolving anti-inbreeding mechanisms is of high importance.

When two very genetically similar organisms get together, there’s a high chance that their offspring will inherit genetic abnormalities that they happen to have, such as hemophilia.

Unless your parents happen to have genes that code for supernatural powers, inbreeding is not such a great idea.

In the wild, low genetic diversity is often seen in endangered animals, and inbreeding is thus very concerning. This often results in propagation of harmful recessive alleles.

Kessler, who led the study, played male mating calls and alarm cries for 10 adult female gray mouse lemurs. Each lemur was presented with her father’s cries, as well as those of an unrelated males’.

The researchers then recorded the level of attention that the lemurs paid to each call, as exhibited by staring behaviors or running over to the broadcasting speaker.

Results showed that the female lemurs paid equal attention to alarm calls from fathers and unrelated males, a finding that the researchers reported in a soon-to-be-published issue of the journal BMC Ecology.

However, when it came to what mattered in terms of perpetuating the species — that is, mating calls — the lemurs were much more attentive to the calls of unrelated males. Compared to when they heard their father’s cries, the lemurs approached the non-kin speakers faster. They also stayed longer to locate the source of the sound.

According to Kessler and colleagues, a big brain and complex social life are not needed for paternal voice recognition. Rather, it is the complexity of the brain itself that matters.

In fact, the ability to recognize kin may have allowed complex social structures to form in evolutionary history.

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