Social dominance in bank voles depends on the size of their genitals

Researcher Dr Jean-Francois Lemaitre from the University of Liverpool with colleagues in France and Switzerland, studying the social dominance in bank voles, (Myodes glareolus), has come up with the finding that social dominance for bank voles depends on the size of their genitals. 

Dominant males invariably had wider penis bones. The researchers say differences in the genitalia of dominant and subordinate males could be a factor contributing to the fertilisation advantage of dominant males under sperm competition. They also found evidence of positive allometry and a relatively high coefficient of phenotypic variation in the baculum width of male bank voles, consistent with an influence of sexual selection.

The researchers sign off like this” We conclude that dominant male bank voles may benefit from an enlarged baculum under sperm competition and/or cryptic female choice and that differences in penile morphology according to male social status might be important but as yet largely unexplored source of variation in male reproductive success.”

  

Journal reference

Genital morphology linked to social status in the bank vole (Myodes glareolus)

Jean-François Lemaître, Steven A. Ramm, Nicola Jennings and Paula Stockley

Behavioral Ecology and Sociobiology

DOI: 10.1007/s00265-011-1257-4