Indirect genetic benefits and the maintenance of genetic variation in male mating success. — ASN Events

Indirect genetic benefits and the maintenance of genetic variation in male mating success. (#20)

Robert J Dugand 1 , Joseph Tomkins 1 , Jason Kennington 1
  1. The University of Western Australia, Nedlands, WA, Australia

The lek paradox – that persistent female choice for genetic benefits should preclude choice from resulting in genetic benefits – has long intrigued evolutionary biologists. The constant influx and transient persistence of new mutations into populations could help in resolving the lek paradox by explaining the maintenance of genetic variation in traits affecting male mating success, particularly if these traits are represented by many loci. This would be true if mating success was genetically correlated with condition, a trait which is expected to be affected by many genes and hence thousands of loci. Such condition-dependent mating success would lead to the expectation that variation in mating success was due to differences in the mutational load among males and, consequently, that mating success itself should be susceptible to inbreeding depression and display positive pleiotropy with other life-history traits which are also condition-dependent (i.e. ‘good genes’ benefits). Here, we test these predictions by applying divergent selection on male mating success for 14 generations in the fruit fly, Drosophila melanogaster and then quantify key components of fitness for both outbred and inbred individuals. Males from success-selected lines had 17.9% greater mating success than males from failure-selected lines. Overall, mating success was prone to inbreeding depression, with outbred individuals recording 9.7% more matings than inbred individuals, indicating that mutational load affects mating success and therefore mating success is genotypically condition-dependent. There was no significant interaction between cross type (inbred or outbred) and selection regime (i.e. no difference in mutational load between selection reigmes). Additionally, egg-to-adult viability was not prone to inbreeding depression and was not different across selection regimes. Our results indicate that, while females enjoy the indirect genetic benefit of improved male mating success of their sons (i.e ‘sexy sons’), overall we found no evidence for good genes benefits gained through precopulatory sexual selection.