POLYANDROUS, SPERM-STORING FEMALES - CARRIERS OF MALE GENOTYPES THROUGH EPISODES OF ADVERSE SELECTION

In the pseudoscorpion, Cordylochernes scorpioides, males experience se xual selection in two disparate and well-defined habitats. Populations inhabit decaying trees for several generations before dispersing unde r the elytra of the harlequin beetle, Acrocinus longimanus. Males comp ete to monopolize beetle abdomens as strategic sites for inseminating dispersing females. Using single-locus minisatellite DNA profiling to assign paternity for the offspring of dispersing females we found a st rong, positive correlation between male size and reproductive success in the beetle environment. However, this intense selection is undermin ed by polyandry and the ability of females to score sperm and produce mixed-paternity broods. Although beetle-riding males achieved fertiliz ations with 70% of the females, paternity could not be assigned for 57 % of the offspring. It is likely that many of these offspring were the products of within-tree inseminations since, in a sample of females i ntercepted in the act of boarding beetles, most (86%) carried sperm fr om pre-dispersal matings within trees. Polyandry and sperm storage may therefore enable smaller males unable to monopolize beetle mating ter ritories, to circumvent the bottleneck of dispersal-generated sexual s election and thereby transmit their genes to future tree populations. Sperm stored within Females can thus provide the kind of resistant lif e-history stage shown by recent modelling to be critical for the maint enance of genetic variation by temporally fluctuating selection.