Author: Constantino de Jesus Macias Garcia and Michael Ritchie

How Animal Genes Go into Battle to Dominate Their Offspring

The burdens of becoming parents are often shared unequally between male and female animals. This is particularly true of species that give birth to live young, where male duties such as defending the breeding territory and building dens or nests rarely compare with the ordeals of pregnancy and labour. You might have thought that animals just “accept” this imbalance and get on with it. But actually, they compete over how much each parent contributes. This isn’t like the competition to win a mate, with locking horns or displays of plumage. Instead this remarkable battle takes place at the level of the genes. It now appears it may have evolved very early in animal evolution, perhaps among the first child-bearing animals. What is more, it may even help to explain why animals diversified into different lineages. Creatures great and small One arena in which this battle plays out is over the size of offspring. In principle it’s in both a mother’s and father’s interests to produce bigger newborns, since they are more likely to prevail in …