Lack of sibling avoidance during mate selection in the butterfly Bicyclus anynana

Species susceptible to inbreeding depression are hypothesized to combat
this problem through a number of different mechanisms, including kin
recognition. For species with kin recognition, it is unknown if filial
recognition is innate or due to prior juvenile experience with siblings.
Here, we first test for the presence of kin recognition, and then test
these two hypotheses for the development of filial recognition, in the
butterfly Bicyclus anynana, a species that suffers from
inbreeding depression when forcibly inbred but recovers within a few
generations when allowed to breed freely. We evaluate whether the rapid
recovery from inbreeding depression is associated with either innate or
learned filial recognition. First, we determined whether females innately
prefer unrelated males over sibling males using females reared in
isolation and then given a choice between an unrelated and a sibling male.
Then, we determined if females raised with siblings learned to detect and
avoid mating with siblings as adults when provided a choice between an
unrelated male and a sibling male. Finally, we determined if females
raised with siblings could learn to detect and avoid mating with familiar
siblings when given a choice between familiar and unfamiliar siblings. We
found that females mated randomly in all three choice combinations.
Observed male behavior also did not influence female mating outcome. Our
results suggest that adult females do not innately avoid or learn to avoid
siblings during mate selection, and that filial detection may not be as
critical to reproductive fitness in B. anynana as
previously thought.