A male tree cricket on a Hyptis suaveolens plant at the Indian Institute of Science, Bengaluru. Credit: Ananda Shikhara Bhat

To make sure their appeals for a mate can be heard loud and clear, tree crickets (Oecanthus henryi) cut a hole in a leaf and call through it, using it like a megaphone.

Called ‘baffling’, it is one of the three behaviours of male tree crickets1 that researchers from the Centre for Ecological Sciences at the Indian Institute of Science in Bengaluru studied. They found that baffling males have greater success at finding a mate than those who call without baffling, or remain silent in homogenous habitats of single or connected bushes.

But all males have equal mating success in structured habitats where a cricket flies from one bush to another, the real habitat of southern Indian scrublands. “We were curious to find why baffling, a strategy with so many advantages is not so common in nature,” says researcher Mohammed Aamir Sadiq.

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The team used a complex mathematical model that simulates the fate of each individual in a population rather than cohorts to find this out.

This individual-based model simulation relied on previously collected field data such as bush size, caller volume, the distance between the bushes, and the frequency of tree crickets flying from one bush to another or within the same bush.

About 500 individual tree crickets — baffling, calling, and silent males, and equal number of females — interacted in one simulation run. Researchers recorded the number of couplings and mating success for each male, helping measure the mating success of each tactic employed by the individuals.

“We incorporated multiple ecological factors and empirical data to create a model that answers evolutionary questions in sexually signalling organisms,” Sadiq says.

In the real world with competing interests, animals move across different type of habitats. This study shows that such movement affects how mates are chosen, says Natasha Mhatre, Canada Research Chair in Invertebrate Neurobiology, at the University of Western Ontario in Canada. “Factoring in ecology explains the co-existence of three different mate attraction strategies, rather than one optimal strategy.”

Studies on fitness of alternative reproductive tactics often overlook the habitat by bringing animals into the laboratory and simplifying the experimental conditions. “Observing animals in the wild is challenging but essential,” Sadiq says.