Abortion of low-viability offspring may be driven by either genetic factors or environmental stress.
[4][6] Developmental selection can also occur as cell lineage selection due to differential growth rates among germ cell lineages in the apical meristem.
This kind of selection can help to remove low-fitness meiotic and somatic mutations from populations of plants.
Like with pollen competition, sperm is often produced in excess compared to the number of available eggs that can be fertilized.
For example, in house mice, the newly born pups are eaten by the mother if they do not squeak or cry out when the mother eats the umbilical cord connecting to the pup.