Females decide whether ambitious males float or flounder

Jan 30, 2008

Aggression, testosterone and nepotism don’t necessarily help one climb the social ladder, but the support of a good female can, according to new research on the social habits of an unusual African species of fish.

The study, published today in the journal Proceedings of the Royal Society, highlights the complex relationship between social status, reproductive physiology and group dynamics.

“We found that changes in social status were regulated by the most dominant female in a social group”, says John Fitzpatrick, lead researcher and a graduate student in the department of Biology at McMaster University. “In fact, dominant females seemed to act as gatekeepers, allowing only males larger than themselves to move up in status and become dominant.”

Males rising to a dominant social position, says Fitzpatrick, instantly altered their behaviour, becoming more aggressive. In addition, they dramatically ramped up their reproductive physiology, almost doubling the size of their testes in one week.

Working underwater off the Zambian shores of Lake Tanganyika in Africa, the researchers examined how males respond to changes in social position in the cichlid fish, Neolamprologus pulcher. This species lives in permanent social groups made up of a dominant male and female breeding pair and subordinate males and females that help this pair look after young and defend territory.

By removing the male breeders, researchers created vacancies and provided an opportunity for subordinate males to rise through the ranks.

“Hormones and genetic relationships didn’t necessarily determine who gets to be top dog,” says Sigal Balshine, the senior author on the study and an associate professor in the department of Psychology, Neuroscience & Behaviour. “Most folks would have thought that how aggressive you are, how big and powerful you are or how much testosterone you have might be important in understanding status change and dominance rankings. Our study combined several approaches to show that simply isn’t the case – instead, the female and the social landscape are key.”

Source: McMaster University

Explore further: NYSCF Research Institute announces largest-ever stem cell repository

add to favorites email to friend print save as pdf

Related Stories

'Red effect' sparks interest in female monkeys

Oct 17, 2014

Recent studies showed that the color red tends increase our attraction toward others, feelings of jealousy, and even reaction times. Now, new research shows that female monkeys also respond to the color red, ...

Are male brains wired to ignore food for sex?

Oct 16, 2014

Choosing between two good things can be tough. When animals must decide between feeding and mating, it can get even trickier. In a discovery that might ring true even for some humans, researchers have shown that male brains ...

Why do people risk infection from bat meat?

Oct 09, 2014

Ebola, as with many emerging infections, is likely to have arisen due to man's interaction with wild animals – most likely the practice of hunting and eating wild meat known as 'bushmeat'. A team of researchers ...

Recommended for you

New feather findings get scientists in a flap

16 hours ago

Scientists from the University of Southampton have revealed that feather shafts are made of a multi-layered fibrous composite material, much like carbon fibre, which allows the feather to bend and twist to ...

User comments : 0