BIOL208 Lecture Notes - Lecture 7: Ecological Niche, Disruptive Selection, Zygote
29 Mar 2018
School
Department
Course
Professor
Document Summary
Changes in allele frequency over time; occurs mainly through natural selection (results in adaptation) or genetic drift and can occur quickly (over generations) Macroevolution: broad patterns of evolutionary change above species level. It is changes occurring on geological time scales. Distinction between microevolution and macroevolution is arbitrary; they are fundamentally identical processes on different time scales (macroevolution is the result of cumulative microevolution aka the gradual compounding of small changes) Biological species concept (bsc): a species consists of a group of actually or potentially interbreeding individuals. They are reproductively isolated from other such groups. Gene flow between populations holds a species together genetically. Concept based on the potential to interbreed rather than on physical similarity. Cannot be applied to fossils or asexual organisms (including all prokaryotes) It suggests that two different species would never mate and produce offspring. But, gene flow can occur between distinct species (successful hybridization) Morphological species concept: defines a species by structural features.
