Adaptation and genetic conflict

Genes that increase organism fitness can come to prominence as a result of natural selection, leading to the appearance of organismal design, or ‘adaptation’. However, genes that compromise organism fitness can also come to prominence if they are able to secure a selfish propagation advantage from doing so. Such genes are called ‘selfish genetic elements’. I consider the consequences of selfish genetic elements for organismal design (adaptation). First, I consider a fungus in which – strikingly – different nuclei in the same individual may be genetically different from each other (‘chimera’). I show how such diversity could be maintained by natural selection, and what consequences this has on the organism. Second, I consider, in general and in a range of specific biological scenarios, whether selfish genetic elements might be expected to gain control of organism traits. I show that the ‘parliament of genes’ is generally effective in suppressing selfish genetic elements, meaning organism design is generally preserved. Third, I ask whether animals can, in principle, evolve to recognise kin via genetic cues. I show they often can, as long as genetic kin discrimination is favoured, over indiscriminate cooperation and indiscriminate defection, at the individual level (it maximises individual fitness).