How to Calculate Effective Population Size

Effective population size (Ne) is one of the most important parameter in population genetics and conservation biology. It translates census sizes of a real population into the size of an idealized population showing the same rate of loss of genetic diversity as the real population under study. Several conceptually different types of Ne can be distinguished, but the most commonly used ones are those based on the loss of genetic diversity through inbreeding (inbreeding Ne) and through genetic drift (variance Ne). Often, these two differ considerably, as do census and effective sizes, although, contrary to what is taught in many introductory courses and textbooks, Ne is not always lower than census size (Braude and Templeton, 2009, see also Nunney in this issue). Inbreeding and variance Ne particularly differ when demography changes. However, these relationships are not all that well understood yet, and require further theoretical and empirical attention. Many recent developments in theory, modeling and statistics as well as in molecular biology have sparked new interest in prediction and estimation of Ne and have led to a number of papers documenting recent advancements in the field. This special issue comprises a collection of papers that tackle various theoretical and applied aspects concerning the estimation of Ne under simulated conditions and in natural situations. Contributions were chosen to provide a balanced overview of the topic by summarizing the state of the art (Wang et al. in this issue), providing new developments in theory, improvements in estimation methods, especially in terms of applicability to genome-wide data (Hollenbeck et al.; Jones et al.; Nunney; Waples et al.; Waples, all in this issue), and some case studies employing currently available methods (Coscia et al.; Cousseau et al.; Ferchaud et al.; Laikre et al.; Mueller et al., all in this issue). Although not being comprehensive, the special issue hopes to provide a good overview of the current status of the field as well as providing new advancements. #genetics #populationGenetics #effectivePopulationSize