Published August 18, 2015 | Version v1
Dataset Open

Data from: Sperm competition and the evolution of precopulatory weapons: Increasing male density promotes sperm competition and reduces selection on arm strength in a chorusing frog

  • 1. University of Western Australia

Description

Sperm competition theory assumes a trade-off between precopulatory traits that increase mating success and postcopulatory traits that increase fertilization success. Predictions for how sperm competition might affect male expenditure on these traits depend on the number of competing males, the advantage gained from expenditure on weapons, and the level of sperm competition. However, empirical tests of sperm competition theory rarely examine precopulatory male expenditure. We investigated how variation in male density affects precopulatory sexual selection on male weaponry and the level of sperm competition in the chorusing frog Crinia georgiana, where males use their arms as weapons in male–male combat. We measured body size and arm girth of 439 males, and recorded their mating success in the field. We found density-dependent selection acting on arm girth. Arm girth was positively associated with mating success, but only at low population densities. Increased male density was associated with higher risk and intensity of sperm competition arising from multimale amplexus, and a reversal in the direction of selection on arm girth. Opposing patterns of pre- and postcopulatory selection may account for the negative covariation between arm girth and testes across populations of this species.

Notes

Files

Calling, mating and polyandry probabilities.csv

Files (34.4 kB)

Name Size Download all
md5:04885094f4fc984086d8a3ec4926d5ae
16.5 kB Preview Download
md5:5dd991cb8b77074ae31fdeef8038e749
735 Bytes Preview Download
md5:e0c9f5a7113765cbc24348d6590f25e1
17.2 kB Preview Download

Additional details

Related works

Is cited by
10.1111/evo.12766 (DOI)