BIOL 152 9thEdition Lecture 4Outline of Last Lecture I. Genetic Drift Can Result In:Outline of Current Lecture I. Why Define a SpeciesII. Reproductive IsolationCurrent LectureI. Why define a species Why are species the key evolutionary unit?A. What is a species?o Groups of actually or potentially interbreeding natural populations, which are, reproductively isolated from other groups- What’s key to the biological species concept?o Reproductive Isolation- What types of organisms would the BSC NOT apply to?o Dinosaurs (extinct), asexual bacteria, and ring speciesB. How else can we “identify” a species?o Morphospecies - You find two bacteria that reproduce asexually and look alike, how might you determine if they are different species?o Grow them under different environmental conditions, grow them on differentnutrient sources, AND analyze their DNA for similaritiesC. How can populations be reproductively isolated?- Intrinsic Mechanisms:o Internal characteristics- Extrinsic Mechanisms, external factorsII. Reproductive Isolationa) Ecological Isolationo Occupy different habitatsb) Temporal Isolationo Mating times are differentc) Behavioral IsolationThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Courtship or mating displays differd) Mechanical Isolationo Parts don’t fit e) Gametic Isolationo Egg AND sperm are not compatiblef) Hybrid Inviability or Infertility- Two species of garter snakes live in the same geographic area. One lives mainly n water while the other lives mainly on land. They do not interbreed. What type of reproductive isolation is this?o Ecological and Pre-zygotic- Pre-zygotic Barrier: impedes mating between species or hinders fertilization- Post-zygotic Barrier: prevents hybrid zygotes produced by two different species fromdeveloping into viable, fertile