Did life history evolve in response to parasites in invasive populationsof Melanoides tuberculata?

摘要

Enemy release and rapid evolution are often assumed to promote biological invasions. In the parthe-nogenetic snail Melanoides tuberculata, one invasive strain (MAD) was assumed to benefit from enemyrelease until a heavily parasitized population was found in Colombia (in the area of introduction). Thispopulation is prosperous despite important losses in the reproductive potential due to a high prevalenceof a trematode that castrates snails. We studied genetic variation in life-history traits among five pop-ulations from the invaded area to test whether life histories had recently evolved in the parasitizedpopulation in such a way that snails have more chance to reproduce before being parasitized. We findsignificant genetic differences among populations, though they are not in the expected direction. Indi-viduals from the parasitized population were smaller at birth, grew slower, and reproduced later and ata bigger size than individuals from the non-parasitized populations. We conclude that the life-historytraits of this snail strain did not need to evolve in order to allow population renewal in the invaded area,even in the presence of parasites. This implies that enemy release and/or rapid evolution were notnecessary for this strain to invade.