Unit of selection and Confirmation of Evolutionary Theory" provides a basic "philosophical" introduction to the debate. Below, cases of selection at the genic, cellular, individual and group level from within the multi-level selection perspective are presented and discussed. George C. Williams in his influential book "Adaptation and Natural Selection" was one of the first to present a gene-centered view of evolution with the gene as the unit of selection, arguing that a unit of selection should exhibit a high degree of permanence. Richard Dawkins has written several books popularizing and expanding the idea. According to Dawkins, genes cause phenotypes and a gene is
The Genetical Theory of Natural Selection chapter, Fisher considers the nature of inheritance, rejecting blending inheritance, because it would eliminate genetic variance, in favour of particulate inheritance. The second chapter introduces Fisher's fundamental theorem of natural selection. The third considers the evolution of dominance, which Fisher believed was strongly influenced by modifiers. Other chapters discuss parental investment, Fisher's geometric model, concerning how spontaneous mutations affect biological fitness, Fisher's principle which explains why the sex ratio between males and females is almost always 1:1, reproductive value, examining the demography of having girl children. Using his knowledge of statistics, the Fisherian runaway, which explores how sexual selection can