There are a small number of organisms, so far I'm aware only of mites and aphids, which practice telescopic generations, where the a female is pregnant with a daughter that is, itself, already pregnant, meaning the adult is carrying two generations within itself.
I'm trying to better understand the evolutionary advantage of this, specifically when compared to the 'normal' evolutionary strategy of non-telescopic generations but giving birth to more young.
In both cases, telescopic generations vs increased young, the mother invests the same amount of resources towards the pregnancy, be it through multiple daughters or fewer daughters but a head start on granddaughters. At first glance it would seem this would make both strategies about equal in reproductive success.
In the case of mites which reproduce sexually, by mating in the womb, I can see one potential advantage of increased genetic diversity...presuming there is any noticeable difference between phenotype of grandchildren in a species that practices serial obligatory incest. Since I'm not certain how large a difference in phenotype children can be expected to have after genes have mostly homogenized I'm not certain how large an advantage this may actually offer, if any. It also doesn't explain the advantage in the case of aphids which are clonal when practicing telescopic generations
So, there any other reasons I'm missing for why telescopic generations would be preferable to birthing more daughters?