Context

It is a well-known fact that males of different species compete for the attention of females to mate with. In species where the female mates with many males, as in Drosophila (fruit fly) the sperms extend this competition to the post-copulatory domain. This is known as post-copulatory sexual selection.

In news

A study of fruit flies bred in the lab shows that they may actually evolve to modulate their reproductive traits based on the extent of competitiveness of their competing males.

Study finding

• This study of 150 generations of fruit flies, spanning about six years, shows how the environment can influence evolution of reproductive traits.
• This study shows that over several generations, males actually evolve to modulate their reproductive investment based on their perception of the number and quality of the competition
• It is significant because it shows how male fruit flies change the expression of their reproductive traits depending on the changes in the environment.
• This study shows the evolution of plasticity according to the change in the socio-sexual environment.
• In general, the rapidly changing environment can have a great impact on an organism’s behaviour.
• Acquiring plasticity enables an individual to cope with the fluctuating environment and maintain fitness in adverse conditions

Competing sperm

• In general, post-copulatory sexual selection can be competition between the various sperm in the female reproductive tract to fertilise the egg, and also sperm choice mediated by the female reproductive tract.
• The experiments demonstrated that first, males can plastically modulate their reproductive investment in response to change in socio-sexual environment experienced in early-life.
• Secondly, evolution under different operational sex ratios led to divergence of male reproductive investment patterns.
• The identity of early-life competitors can influence the pattern of reproductive investment.
  

Source: The Hindu