Christi Lynn's Test #2 Notes (2003)

Christi Lynn's Test #2 Notes (2003) - Evolution of Species...

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Unformatted text preview: Evolution of Species Living things can be grouped. Species- Latin- kind or appearance. There is individual variation in members of the same species. Natural selection acts on it. 1927- Ernst Mayr- Harvard professor that led a group of ornithologists into the Arafat Mountains in New Guinea. They found a tribe and questioned them about birds: they had 138 different names for birds, but there were only 137 species. Ideas about species: 1. Typological species- static, immutable, and typified by its ideal form 2. Morphological Species- used most often today. Looks at form, shape, and morphology. Ed Ruper identified new invertebrate species and put them into groups. The problem is that there is an extreme level of phenotypic variance. 3. Biological species- proposed by Mayr in 42. Def- a genetically distinct group of natural populations sharing a common gene pool and being reproductively isolated from all other such groups. Conspecific- members of the same species. There is phylogentic relatedness. Intraspecific- between two individuals of the same species. ex hummingbirds Interspecific- between two individuals of different species Anatomical, physiological, behavioral, differences between species. There has to be cessation of gene flow between species. Species Concepts: pg. 447-449 1. Biological 2. Morphological 3. Recognition 4. Cohesion 5. Ecological 6. Evolutionary Exceptions to biological concept: Gray Wolf + Husky = Pawnee. They are sterile. Female African Lion + Male Tiger = Tiglon. Also sterile. Looks like a female lion with vertical streaks. Male African Lion + Female Tiger = Liger. When you have forms that reproduce asexually, they arent affected by interbreeding. Ex. Prokaryotes, some protists, some fungi. Peripheral populations- genes are passed between species not directly interbreeding. Alapatric- separated by large ocean Mechanisms for speciation: 2 types of evolutionary processes: Phyletic Evolution (Speciation) a.k.a. Anagenesis- existing species thru time accumulates gradual number of changes and replaces itself. Not the most prevalent. Cladogenesis a.k.a. Divergent speciation- Greek clados means branch. From one existing species one or more new species appear but original species still exists. It increases diversity by increasing number of species. 3 modes of speciation based on geographical relationship to a species to its ancestral form: 1. Allopatric- an original pop of organism that becomes separated into 2 separate pops and they evolve along their own separate lines. Depends on separation of gametes. Ex- squirrels of the Grand Canyon. Pup fish- found in Death Valley. a. Splinter group (peripheral isolate)- when just a small part of a pop is cut off. Cline can affect if. Founder effect and genetic drift. Ex- Darwins finches. Thought to be descended from single species....
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Christi Lynn's Test #2 Notes (2003) - Evolution of Species...

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