In This Chapter

Bookmark and Share

Chapter Summary

  1. Asexual reproduction involves the production of offspring from unfertilized gametes. Sexual reproduction involves the joining together of genetic material from two parents to produce a progeny that has genes from each parent.
  2. Mode of reproduction—sexual versus asexual—can be inferred by observation, but also by molecular genetics and phylogenetic comparisons.
  3. In eukaryotes, species that reproduce only asexually are rare and short-lived on an evolutionary timescale. Their phylogenetic distribution has a "twiggy" appearance.
  4. Despite its ubiquity, sexual reproduction has many costs associated with it, including the "twofold cost of sex" and the breaking up of favorable gene combinations.
  5. The advantages of sexual reproduction can be divided into two general categories: (a) sexual reproduction is more efficient at purging deleterious mutations from a genome than asexual reproduction, and (b) natural selection favors the production of more variable offspring through the processes of recombination and gametic fusion.
  6. The repair of double-stranded DNA may have played a role in the origin of sexual reproduction.