The Selfish Jean

The selfish gean idea was popularized by Richard dawkins. It stands in stark contrast to other people who argue for group selection, or even species selection. If therewas mutation in the gene that controls when a bird nests, such that the bird didn't nest in april but instead started nesting in march, then the birds would find there are more nesting sites. And so if the mutant gen causes the bird, an individual bird, to start nesting earlier, then that bird might have offspring which is more likely to survive because there's less competitors at that time. So what can happen then is that those particular birds have an advantage over the ones that are nesting in aprils.