Sperm competition between brothers and female choice

Females of the red jungle fowl (forest chicken) mate with multiple males, which can create competition between sperm of different males in order to fertilize the egg. In my PhD thesis, I explored the effect of brotherhood on sperm competition and female choice. Interestingly, the brother of the first male that the female has mated with invests more sperm in the female than the non-brother of the first male mate. However, the female ejects a higher proportion of sperm from the brother of the first mate and favours the sperm of the non-brother, facilitating a higher fertility by the non-brother’s sperm.
In addition to the main story, we showcase some of the interesting biology of sperm. First, sperm quality differs and while some move faster and are more forward-moving, others move in circles. Second, sperm of multiple males can interact with one another, sometimes even antagonistically.
Inspired by various sports, the dance movements in this video reflect the competitive nature in the sperm world. The two original music pieces in this video are (1) ‘Animal Love’, which is about the variety of sexual behavior in different species and (2) ‘Scenester’, a piece telling the story about a girl who keeps changing her ways and males trying to keep up with her.


Sperm competition between brothers and female choice from Cedric Kai Wei Tan on Vimeo.