TECTONICS_AND_EVOLUTION_2010

TECTONICS_AND_EVOLUTION_2010 - PLATE TECTONICS,...

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Unformatted text preview: PLATE TECTONICS, BIOGEOGRAPHY & EVOLUTION 7 MAJOR LINES OF EVIDENCE PLATE TECTONICS, BIOGEOGRAPHY & EVOLUTION Ecological biogeography : analysis of present- day distribution patterns in terms of current environmental conditions (e.g. climate, soil type) and interactions with other species that limit distributions. Historical biogeography : analysis of present- day distribution patterns in light of historical factors that may have inFuenced the distribution of species. Average coldest month / C Average warmest month / C PLATE TECTONICS, BIOGEOGRAPHY & EVOLUTION Ecological biogeography : analysis of present-day distribution patterns in terms of current environmental conditions (e.g. climate, soil type) and interactions with other species that limit distributions. Historical biogeography : analysis of present-day distribution patterns in light of historical factors that may have inFuenced the distribution of species. IMPACT OF PLATE TECTONICS ON THE EVOLUTION OF LIFE A. Continents are pulled apart B. Continents merge C. Islands are created D. Barriers to dispersal appear within continents What is a species? Species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups. (Biological Species concept. Ernst Mayr, 1940) 1) Phyletic evolution = evolution within a lineage 2) Branching evolution = production of new species by divergence from the ancestor species b species a species a species b species c TWO WAYS OF GENERATING NEW SPECIES Phyletic evolution does not result in an increase in the number of species. Branching evolution does. species b species a species a species b species c Two ways to produce new species by branching evolution. SPLITTING BUDDING Ancestor is lost. Ancestor persists. Step 1: Split a large population into two or more, Step 2: Evolution proceeds independently in each, Step 3: Let time pass - and eventually the separated populations will be too different to interbreed ALLOPATRIC (living apart) SPECIATION (SYMPATRIC = coexisting, living together) ALLOPATRIC SPECIATION MODEL CENTRAL POPULATION A D C B A CENTRAL POPULATION B D C A geographic barrier ALLOPATRIC SPECIATION MODEL a) it is unlikely that the two populations will include identical representations of the variation present in the ancestral population ( founder effect ), b) over time, genetic drift is likely to result in an even more limited and distinct representation of the variation present in the ancestral population, c) it is unlikely that the same mutations will occur in both populations, and d) the selection pressures are likely to differ in the two places....
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TECTONICS_AND_EVOLUTION_2010 - PLATE TECTONICS,...

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