Mating status-dependent 'choice' in competitive and non-competitive arenas

To maximize their reproductive fitness, females of many polyandrous
species should display mating status-dependent choice, where they mate
relatively indiscriminately once to ensure reproductive output, and then
become choosy and mate preferentially with higher-quality males. Despite
this potential contrast in choosiness, most mate choice experiments use
virgin females. Here, we tested whether virgin and non-virgin females
differ in their choosiness, and then test whether their choices are likely
to be adaptive. To do so, we measured the latency to mate and the
competitive mating success of male flies from 20 isofemale strains (i.e.,
males that come from 20 different genetic backgrounds). We hypothesized
that male mating success would vary more between strains when non-virgin
females were choosing (captured by 'among-M-strain' variance),
consistent with the theory that virgin females mate reltively
indistriminately. We then performed a series of strain crosses and
measured the egg-to-adult viability (number of adults that emerged from N
eggs) and competitive fitness (numbers of wild-type [focal flies] versus
brown-eyed [competitor flies] flies emerging) of flies emerging from these
crosses. These assays test how strains and/or strain-combinations vary in
their viability and fitness, and thus allow us to determine whether female
choices are adaptive. Most virgin females mated within two hours of males
being introduced, compared with fewer than half of non-virgin females
mating over the same period. However, despite mating more rapidly, virgin
females did not mate indiscriminately, and their ‘choices’ strongly
aligned with those of previously mated females across both the single-male
latency and male-male competition trials. Our results challenge the idea
that virgin females mate relatively indiscriminately and show that female
choice may be more stable than is generally appreciated.