Differentiate between the species concept of sexual and asexual organisms.
Answers
A fundamental drawback to the biological species is the concept is that it is exclusively defined in terms of sexual reproduction. Asexual and cyclically parthenogenetic taxa are obviously excluded from this concept, but it is also true that many species capable of sexual reproduction cannot be easily accommodated within the framework of the biological species concept. Species capable of self-fertilization (e.g., parasitic tapeworms and some plants) and those with mandatory sibling mating are more similar to asexual than to sexually outcrossing species (Templeton, 1989) from the viewpoint of population genetics. Species that freely hybridize (open mating systems) with one or more other species yet maintain their evolutionary identity as species also provide a serious challenge to the validity of the biological species concept. Freely hybridizing species are known from plants, insects, and vertebrates (Templeton, 1989)