Turbellarian taxonomic database

Abstract / Notes

"The expression of an individual's phenotypic traits can be influenced by genes expressed in its social
partners. Theoretical models predict that such indirect genetic effects (IGEs) on reproductive traits should
play an important role in determining the evolutionary outcome of sexual conflict. However, empirical tests of
(i) whether reproductive IGEs exist, (ii) how they vary among genotypes, and (iii) whether they are uniform
for different types of reproductive traits are largely lacking. We addressed this in a series of experiments
in the simultaneously hermaphroditic flatworm Macrostomum lignano. We found strong evidence for IGEs on both
morphological and behavioral reproductive traits. Partner genotype had a significant impact on the testis size
of focal individualsvarying up to 2.4-foldsuggesting that IGEs could mediate sexual conflicts that target the
male sex function. We also found that time to first copulation was affected by a genotype x genotype
interaction between mating partners, and that partner genotype affected the propensity to copulate and perform
the postcopulatory suck behavior, which may mediate conflicts over the fate of received ejaculate components.
These findings provide clear empirical evidence for IGEs on multiple behavioral and morphological reproductive
traits, which suggests that the evolutionary dynamics of these traits could be altered by genes contained in
the social environment."

Return to taxon listing