To call or not to call: Persistence of flexible alternative reproductive tactics in a tree cricket

Alternative reproductive tactics (ARTs) are discrete polymorphisms within sexes of a population that help maximise reproductive success. Although flexible ARTs are frequently encountered, theoretical predictions for why flexible ARTs persist over evolutionary time have rarely been empirically tested. We tested the hypothesis that flexible ARTs will persist if they have equal fitness benefits under a range of ecological contexts. Specifically, we investigated how predation risk affects the expression and fitness consequences of two flexible ARTs: acoustic signalling and being silent, expressed by tree cricket <i>Oecanthus henryi</i> males. In large outdoor enclosures, we exposed natural populations of <i>O. henryi</i> to three different abundances of their predator, the green lynx spider <i>Peucetia viridans</i>. Behavioural observations across successive nights revealed that predation risk did not alter the expression levels of the male ARTs. Male crickets demonstrated an equal likelihood of calling or remaining silent on a night. Silent tree crickets spatially associated with callers and acquired 80% of their matings while hearing other callers, suggesting they employ a satellite strategy to improve fitness. Overall, ARTs resulted in similar mating success across differential predation risk, supporting the hypothesis that equal fitness benefits of flexible ARTs under a range of ecological contexts explain their persistence.<br><br>MethodsData collected to address the question of how alternative reproductive tactics persist in a population across variable ecological contexts. Enclosure experiments were performed using 3 different predation treatments that varied in the predator-prey ratio maintained upto 12 nights. Data was collected every night from 1900 hrs to 2130 hrs during which tree crickets are active. Calling and mating was sampled once every 10 minutes (16 times per night). Data is processed at the per individual per night level.