Alternative Reproductive Tactics in Tree Crickets

Trait polymorphisms are widespread in nature, and explaining their stable co-existence is an important problem in ecology and evolution. Alternative reproductive tactics (ARTs), in which individuals of one or more sex exhibit discrete, discontinuous traits in response to reproductive competition, represent a special case of trait polymorphism in which the traits are often complex, behavioral, and dynamic. Thus, studying how alternative reproductive tactics are maintained may provide general insights into how complex trait polymorphisms are maintained in populations. Males of the tree cricket Oecanthus henryi use one of three distinct ARTs to obtain mates:

• Bafflers construct an acoustic structure called a `baffle' using leaves and call from within this baffle. The baffle increases the amplitude of their calls, and females are known to prefer louder males.
• Callers simply call from perches to attract mates. The amplitude of the call of a caller is less than that of a baffler.
• Silent males do not call at all, and simply wait silently for females.

In collaboration with Mohammed Aamir Sadiq, a Ph.D. student in Dr. Rohini Balakrishnan's lab at IISc, I have constructed a computational individual-based model (IbM) to describe these three ARTs and examine each of their mating successes using extensive inputs from field and laboratory experiments.

Our results show that the co-existence of these tactics over ecological time scales is facilitated by the spatial structure of the landscape they inhabit, which serves to equalize the otherwise unequal mating benefits of the three tactics. We also show that this co-existence is unlikely if spatial aspects of the system are not considered. This work is currently a preprint in which Aamir and I are co first authors Sadiq, Bhat et al. 2024.