In This Chapter

Bookmark and Share

Chapter Summary

  1. Interactions between alleles at different genetic loci play an important role in the evolutionary process.
  2. When traits are polygenic—that is, influenced by multiple loci—Mendelian inheritance can give rise to a near-continuous range of variation.
  3. To create population genetic models of evolutionary change at multiple loci, we need to track haplotype frequencies rather than merely tracking allele frequencies.
  4. When there are statistical associations between alleles at different loci, we say there is linkage disequilibrium in a population. The magnitude of these associations is quantified by the coefficient of linkage disequilibrium D.
  5. Linkage disequilibrium can be created by evolutionary processes, including mutation, selection, migration, and drift.
  6. Genetic recombination breaks down linkage disequilibrium over time.
  7. Physical linkage on the chromosome facilitates the processes of genetic hitchhiking, background selection, periodic selection, and clonal interference.
  8. The adaptive landscape metaphor provides a way to think about how phenotypes or genotypes change over evolutionary time as a consequence of natural selection.
  9. Quantitative genetic approaches allow us to model and predict how continuous or quantitative characters change as a result of natural selection.
  10. Narrow-sense heritability measures the fraction of phenotypic variation in a population due to the additive genetic variation on which selection can efficiently operate. If we know the narrow-sense heritability of a trait in a population, we can use the breeder’s equation to predict how that trait will change in response to natural or artificial selection.