Biology 1201A Lecture Notes - Lecture 19: Heterosis, Reproductive Isolation, Ecological Niche
4 Jan 2018
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Document Summary
19. 2 definition of species (cid:498)the nature of species is controversial in biology and philosophy. Biologists disagree on the definition of the term (cid:498)species(cid:499) Biological species concept defines a species as a group of organisms that can successively interbreed and produce fertile offspring. Phylogenic species concept defines a species as a group of organisms bound by a unique ancestry. Ecological species concept defines a species as a group of organisms that share a distinct ecological niche. Several problems with the biological species concept defined above: does not deal as well with the many species that reproduce asexually, patterns of reproduction can blur the definition of species. Androdioecous organisms exist as natural populations of functional males and hermaphrodites but include no true females. Gynogenetic species, as the name implies, have only females. Using biological species concept, neither are covered by the traditional definition of species. Definition also do not apply where there is hybridization, when two species interbreed and produce fertile offspring.
