A statistical approach to understanding reproductive isolation in two sympatric species of tree crickets

Abstract

In acoustically communicating animals, reproductive isolation between sympatric species is usually maintained through speciesspecific calls. This requires that the receiver be tuned to the conspecific signal. Mapping the response space of the receiver onto the signal space of the conspecific investigates this tuning. A combinatorial approach to investigating the response space is more informative as the influence on the receiver of the interactions between the features is also elucidated. However, most studies have examined individual preference functions rather than the multivariate response space. We studied the maintenance of reproductive isolation between two sympatric tree cricket species (Oecanthus henryi and Oecanthus indicus) through the temporal features of the calls. Individual response functions were determined experimentally for O. henryi, the results from which were combined in a statistical framework to generate a multivariate quantitative receiver response space. The predicted response was higher for the signals of the conspecific than for signals of the sympatric heterospecific, indicating maintenance of reproductive isolation through songs. The model allows prediction of response to untested combinations of temporal features as well as delineation of the evolutionary constraints on the signal space. The model can also be used to predict the response of O. henryi to other heterospecific signals, making it a useful tool for the study of the evolution and maintenance of reproductive isolation via long-range acoustic signals.

Delineating the calling pattern of Oecanthus indicus from native and non-native plant species

“…Thus, host preference could be an important attribute that affects the reproductive fitness of an acoustically communicating insect. Studies have reported the association of Oecanthus species with a non-native plant, H. suaveolens ( Bhattacharya, Isvaran & Balakrishnan, 2017 ). The association of Oecanthus species with non-native plants can provide an excellent system to investigate the effect of preference based on various call characteristics.…”