Ar. Kraaijeveld et al., ABSENCE OF DIRECT SEXUAL SELECTION FOR PARASITOID ENCAPSULATION IN DROSOPHILA-MELANOGASTER, Journal of evolutionary biology, 10(3), 1997, pp. 337-342
Resistance against parasites may play a role in female mate choice, es
pecially if males that have actually survived parasitism can be discri
minated from males that have not been parasitised. Larvae of several D
rosophila species are subject to attack by hymenopteran parasitoids, b
ut have the ability to kill the parasitoid egg through the process of
encapsulation. Because an encapsulated egg remains visible in the abdo
men of the adult fly throughout its life, its presence in a male signa
ls to a female that the male has the genes to survive parasitism. The
hypothesis that females preferentially mate with males bearing an enca
psulated egg in their abdomen was tested using D. melanogaster. No ind
ication was found for this female preference. The absence of preferenc
e for males with ''good genes'' could result from sensory constraints
in the female or a negative correlation between encapsulation ability
and some other fitness component. Alternatively, it is hypothesised th
at the black abdominal ends of the males of many species in the melano
gaster-group evolved to mimic encapsulated eggs, leading to the breakd
own of capsule recognition by the female.