Divergence in male mating tactics between two populations of the soapberry bug: I. Guarding versus nonguarding

Scott P. Carroll Department of Biology, University of Utah, Salt Lake City, UT 84112, USA I compared male allocation to prolonged mate guarding versus not guarding between two populations of the soapberry bug {fadera haematoloma) that differ in adult sex ratio: Oklahoma, USA (mean ± SD adult sex ratio, 2.70 ± 0.95 males per female), and Florida, USA (1.09 ± 0.26 males per female). To predict the reproductive performance of each mating tactic in each population, I collected data on search time per mating, time required for guarding to be effective, sperm competition, female remating propensity, and female resistance to guarding. Search time alone differed significantly between the populations, being much greater in Oklahoma (estimated as 26.2 h per mate) than in Florida (estimated as 9.6 h per mate). For males in each region, these data were used to model the costs and benefits of guarding for different numbers of oviposition bouts versus not guarding. The reproductive rate of nonguarders in Oklahoma is exceeded by that of guarders who remain with a female for more than one oviposition bout, but in Florida, the reproductive rate of nonguarders is only exceeded by that of guarders who remain with a female for at least three ovipositions. Consistent with the model, Oklahoma males in field arenas guarded more frequently than did Florida males. However, nonguarding was common in both populations, and guarding durations were highly variable.