Selection on an Animal with a Dominant Genetic Disorder

[wasteofo2]

Let's say you have a hypothetical species of animal and on average, these animals reach sexual maturity at age 10, will breed from age 10 to age 20, and die at age 50.

Let's also say that there is an individual who is homozygous for a unique genetic disorder that will cause him to die at age 30, instead of age 50, and that this disorder only starts to kick in at age 25; after he has done all his breeding. Also, let's say that this disorder is dominant, so this individual's offspring will invariably die at age 30 as well.

If the negative aspects of this disorder do not begin to manifest themselves until age 25, and this individual breeds normally, is there any mechanism of selection against this individual and his offspring?

Thanks,
Jacob

 

[honestrosewater]

Just a first thought: If families stay together or offspring depend on parents, there could be effects on breeding. For instance, families may control territory, or children whose parents die soon after giving birth may have a lesser chance of surviving to sexual maturity. Animals could also notice the general healthiness of a family and tend to choose the healthiest, but I don't know how likely this is (I can't think of an animal other than humans that could do this, but I don't know).

 

[loseyourname]

If it was a social animal with offspring that depended upon parental care for a long period of time after birth, it could be selected against, as Rachel pointed out. Even if the young do not depend on parental care, by both parents, for 5-10 years after birth (no animal does outside of humans), there could be other effects of this gene that physically manifest themselves earlier than breeding age that a potential mate could pick up on and be turned off by. It doesn't even have to be the effect of the same gene; it could be the effect of a gene that is simply located very close to the disease gene. I really don't think there are any animals out there, however, that discriminate sexually against mates that will die young, as long as they are sexually healthy and can provide protection during pregnancy and infancy. Even humans don't discriminate like that.

 

[hitssquad]

Individual selection and group selection

I really don't think there are any animals out there [...] that discriminate sexually against mates that will die young

In addition to individual animals, there are animal groups.