Fish study links brain size to parental duties

Male stickleback fish that protect their young have bigger brains than counterparts that don't care for offspring, finds a new University of British Columbia study.

Stickleback fish are well known in the animal kingdom for the fact that the male of the species, rather than the female, cares for offspring. Male sticklebacks typically have bigger brains than females and researchers wanted to find out if the difference in size might relate to their role as caregivers.

In the study, published recently in Ecology and Evolution, researchers compared regular male sticklebacks to male white sticklebacks, which do not tend to their offspring. They found evidence that this change in male behaviour – giving up caring for the young – occurred at the same time the white stickleback evolved a smaller brain.

"This suggests that regular sticklebacks have bigger brains to handle the brain power needed to care for and protect their young," says Kieran Samuk, a PhD student in UBC's Dept. of Zoology and the study's lead author. "This is one of the first studies to link parental care with brain size."

The white stickleback is a relatively young species that only diverged from other sticklebacks 10,000 years ago, offering researchers some insight into how quickly brains can evolve.

"Our study tells us that brains might change in very drastic ways in a relatively short period of time. This helps us understand how physical changes such as brain size can lead to more complex behavioural changes," says Samuk.