Biology 102Lecture 6Outline of Last Lecture:I. Sexual SelectionII. DarwinIII. AnatomyOutline of Current Lecture:I. How do Species Arise?II. Concepts and Theories on SpeciesHow do Species Arise?- Speciation- the way a new species comes aboutSO how do they happen?- Microevolution- small changes, allele frequency changes but nothing dramatic.- Macroevolution- big changes. It results in the origin of a new species - Branching evolution- when one species splits into 2 and causes diversity in the species- Linear evolution- a change into a new species, there is no new biodiversityCarolus Linnaeus- Swedish physician and botanist- Used physical traits to determine species - Created the binomial system (used to identify species)Concepts and Theories on SpeciesThere are a couple different ideas on how to approach how we should distinguish species- “ A group of populations whose members have the potential to interbreed in nature and produce fertile offspring (who themselves can reproduce)” – Ernst Mayr This can’t work as an identification process because it doesn’t apply to fossils or asexual organisms.- The morphological species concept: classifies organisms based on observable phenotypic traits used for both fossil and living species. Linnaeus’s concept- The ecological concept: defines a species by the role it plays in its environment Ex. Does it decompose things? It’s a fungi. Does it photosynthesize? It’s a plant.Biology 102- The phylogenetic species concept: defines a species as a population of organisms representing an evolutionary lineage Problem with this theory is that people can’t agree on the percentage of what it takes to make something
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