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Drift Load
Drift load, a type of genetic load, is the decline in Fitness (biology), fitness in a population due to the Fixation (population genetics), fixation of deleterious mutations by genetic drift. Drift load generally decreases as a function of effective population size, and is a mechanism of inbreeding depression. If all individuals in a population become homozygous for one allele, that allele is Fixed allele, fixed, and any other alleles at that Locus (genetics), locus are lost from that population by the random evolutionary process of genetic drift. As fixation of deleterious alleles occurs at more loci and variability is lost, drift load increases. With increasing drift load, populations become less fit with each generation, a mutational meltdown, which can lead to an extinction vortex. Strategies to address drift load in endangered species is a goal of conservation genetics. Calculating drift load For realistic values of N_e, the effective population size, and \lambda_D, the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Load
Genetic load is the difference between the fitness of an average genotype in a population and the fitness of some reference genotype, which may be either the best present in a population, or may be the theoretically optimal genotype. The average individual taken from a population with a low genetic load will generally, when grown in the same conditions, have more surviving offspring than the average individual from a population with a high genetic load. Genetic load can also be seen as reduced fitness at the population level compared to what the population would have if all individuals had the reference high-fitness genotype. High genetic load may put a population in danger of extinction. Fundamentals Consider n genotypes \mathbf _1, \dots, \mathbf _n, which have the fitnesses w_1, \dots, w_n and frequencies p_1, \dots, p_n, respectively. Ignoring frequency-dependent selection, the genetic load L may be calculated as: :L = where w_\max is either some theoretical optimum, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
