The theoretical metrics developed, such as genetic variance and heritability (Fisher, 1930; Wright, 1931), provided the quantitative standards necessary for the evolutionary synthesis. Further research has focused on the origin of genetic diversity, its maintenance and its role in evolution. Simple questions such as “who breeds with whom” initiated studies on the relatedness of populations. These investigations led to the formation of metapopulation theory, where a group of spatially separated populations of the same species interact at some level and form a coherent larger group (Hanski, 1998). The discovery of spatial structure in populations was a key element in the early concepts and models of population ecology, genetics.
