BIOLOGY 1M03 Lecture Notes - Lecture 5: Y Chromosome, Dusky Seaside Sparrow, Archaea
Document Summary
Occurs when populations of same species become genetically isolate. Divergence: consequence of natural selection, genetic drift, mutation, &/or biased mating. Can be recognized as distinct species: reproductively isolated from one another, distinct morphological characteristics, independent branches on phylogenetic tree. Genetically isolated: different geographic area, different habitats, one population is polyploid & cannot breed. Gene flow is reduced between populations, may diverge. Species: evolutionarily independent population or group of populations (i. e genetic drift is : biological species concept, morphospecies concept, phylogenetic species concept. Allele frequencies/other characteristics of independent populations divers, over time populations can become distinct species. Assigns individuals to same species if they can actually or potentially interbreed. Biologists categorize the mechanism that stop gene flow between populations as being either prezygotic (before zygote is formed) or postzygotic (after zygote is formed) Sterile: donkey & horse create a mule which is sterile.