Genetic load is the reduction in the mean fitness of a population relative to a population composed entirely of individuals having optimal genotypes. Load can be caused by recurrent deleterious mutations, genetic drift, recombination affecting epistatically favourable gene combinations, or other genetic processes. Genetic load potentially can cause the mean fitness of a population to be greatly reduced relative to populations without sources of less fit genotypes. Mutation load can be difficult or impossible to measure. Many species have mutation rates low enough that substantial genetic load is not expected, but for others, such as humans, the mutation rate may be great enough that load can be substantial. In extremely small populations, drift load, caused by the fixation by drift of weakly deleterious mutations, can threaten the probability of persistence of the population. Migration from other populations adapted to different local conditions can bring in locally maladapted alleles, resulting in migration load. Key Concepts: Genetic load is the reduction in mean fitness of a population caused by some population genetic process. Mutation load is the reduction in fitness caused by recurrent deleterious mutations. Mutation load may be as great as 95% for the human population. Drift load is the reduction in mean fitness caused by genetic drift. In extreme cases, deleterious alleles can reach a frequency of one in a population because of genetic drift. Genetic load can also be caused by recombination breaking up beneficial combinations of alleles, segregation reducing the frequency of fit heterozygotes, or migration bringing less fit alleles into a local population.

Is queer social science possible? Early queer theorists disparaged empiricism as a normalizing, modernist discourse. Nonetheless, LGBTQI+ social scientists have applied queer concepts in empirical projects. Rather than seek a queer method, we ask, Is there an empirical perspective that (ontologically) envisions social relations more queerly—attending to discursive and materialist productions of reality? Dorothy Smith’s work foregrounds people’s activities of engaging texts and satisfies Black queer studies’ and new materialisms’ critiques of early queer theory. Underutilized and often misread, especially its ethnomethodological sensibilities and its vision of actors as relational, practical actors, her work shows how my race is not mine, it is ours; your sexual orientation is not yours, it is ours; their gender is not theirs, it is ours. Smith offers an ontology without essence, grand theory, or normativity, facilitating a range of queer, interpretive projects—from the intersectional to the transnational to the embodied.

Genetic load is the reduction in the mean fitness of a population relative to a population composed entirely of individuals having optimal genotypes.