BIOL 11000 Lecture Notes - Lecture 26: Species Problem, Speciation, Chromosome
4 Dec 2018
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Document Summary
What is a species: 26 different definitions of species, biological species concept, one or more populations of individuals that. Produce fertile offspring: limitations to this definitions, fossil species, don"t know about their breeding, asexual species. Ex: bacteria: organisms separated by great distances, maybe could interbreed but are too far apart. Reproductive barriers: members of species share a common gene pool, freely interbreed with each other, don"t interbreed with other specie because of reproductive barriers. Postzygotic barriers (1) fertilization occurs (2) development fails, or (3) offspring is sterile: pre, habitat, never come into contact, behavioral isolation: Incompatible mating rituals, pheromones: mechanical, reproductive parts not compatible, gametic isolation. Sperm and egg can"t fuse: post, hybrid breakdown, hybrid doesn"t develop or dies soon after birth, sterility, hybrid lives but is infertile. Modes of isolation: allopatric, different homelands, geographic barrier isolates populations, sympatric, same homeland, isolation occur because of sudden genetic alterations.
