Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Reproductive isolation wikipedia , lookup
Evolving digital ecological networks wikipedia , lookup
Catholic Church and evolution wikipedia , lookup
Hologenome theory of evolution wikipedia , lookup
Theistic evolution wikipedia , lookup
The eclipse of Darwinism wikipedia , lookup
Evidence of common descent wikipedia , lookup
3/4/2013 SPECIATION SPECIATION BIOLOGY 11 MECHANISMS OF SPECIATION •Isolation – Divergent Evolution • Natural selection modifies populations from one generation to the next, causing them to evolve. • Sometimes evolutionary changes are so great that some organisms can no longer interbreed with the original species • When this happens it is called SPECIATION ISOLATION • Speciation begins with the isolation of a part of the population through migration or a natural barrier • Ex. Polar bears / Brown bears •Adaptive Radiation •Convergent Evolution ISOLATION/DIVERGENT EVOLUTION IN DARWIN’S FINCHES • When isolated populations evolve independently it is called divergent evolution • If 2 populations remain apart long enough they will become reproductively isolated • Now they are 2 separate species – speciation has occurred ADAPTIVE RADIATION • Over time, new species may evolve from one ancestral species as populations evolve to different niches • Multiple branching of a family tree is called adaptive radiation • “Adaptive” comes from the fact that one ancestral species must adapt to occupy a variety of niches 1 3/4/2013 ADAPTIVE RADIATION… ADAPTIVE RADIATION IN FINCHES • Charles Darwin noticed adaptive radiation in the finches on the Galapagos CONVERGENT EVOLUTION • Different types of organisms with different ancestors evolve similar characteristic s because they occupy similar niches 2