Feminine looking "sneaker" goby male fish end up getting the most sex

Washington, June 16 (ANI): Researchers at McMaster University have discovered the existence of two types of males of a fiercely invasive fish spreading through the Great Lakes, which might help explain how they rapidly reproduce.

They revealed that in addition to round goby males, which guard the nest from predators and look after their offspring, there exists what scientists call "sneaker" males - little males that look like females and sneak into the nests of the larger males.

"The existence of these two kinds of males will help scientists understand how round gobies reproduce, how quickly their populations grow, and track how these populations change over the course of invasion," said Julie Marentette, lead author and a Ph.D. student in the department of Psychology, Neuroscience and Behaviour at McMaster University.

"This has the potential to have a significant impact on how researchers tackle what has become a very difficult problem in the Great Lakes," she added.

The "sneaker" males slip into the nests of big males or pretend to be females.

While analysing the physical, hormonal and sperm traits of hundreds of males, researchers found that the nest-guarding, parental males were big, black and had wide heads and the small female-like sneaker males were tiny, mottled brown and had narrow heads.

Both types of males produced sperm, but sneakers produced more sperm than the parental males, and had bigger testes.

"Prior to our findings, only one type of male reproductive behaviour would have been incorporated into projections and modelling analyses of the population dynamics of round goby invasive capacities", said Sigal Balshine, associate professor in the department of Psychology, Neuroscience and Behaviour and academic advisor on the study.

"Our results will shed light on how populations of this invasive species are likely to grow and spread through time and space," Balshine added.

The research is published in the Journal of Great Lakes Research. (ANI)