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OSU BIOLOGY 1114 - Macroevolution and its Systematics

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Biology 1114 1st Edition Lecture 4Outline of Last Lecture II. StrategyA. How organisms surviveIII. Famous Scientists that contributed to the theory of EvolutionIV. Types of Selection Graphically RepresentedV. Other Means of Evolutiona. Genetic Drifb. Founder Effectc. Bottleneck effectVI. The two levels of Evolutiona. Macroevolutionb. MicroevolutionOutline of Current Lecture: Microevolution and SystematicsVII. How does geographical separation occur?a. Dispersalb. Ways organisms have used to disperseVIII. Adaptive radiationIX. Reproductive isolationX. Reproductive Isolating Mechanisms: prezygotic vs. postzygoticXI. Same species vs. New SpeciesCurrent Lecture- Allopatrick and Aympatrick: How does geographic separation occur?o Dispersal: migration away from original location o Why would something want to disperse? Competition for limited resources motivates organisms to leave/find an area with less competition- Example of dispersal: Insect eggso Have a quality of hard outer shells that protect them from the environment whenbeing dispersedo Dessication: drying out-one of the biggest selective pressures on organisms on land- Examples of dispersalo Geese Flying: fly south for the winter/have the quality of wings to be able to flyThese 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 Strawberries: the seeds on the strawberries are not broken down by digestion so they are dispersed in the feces of the organisms that eat themo Cocklebur: have pricklers that stick like Velcro to organisms that touch them, then disperse through the movement of the organisms they stick to - Organisms have used…o Wind, flight, water, other animals, and “exploding” all as methods to disperseo “R” selection: lay as many as possible eggs in order to have the highest survival rate of offspring because dispersal can kill a lot- Adaptive Radiationo Geographic Speciation on a grand scaleo Example: when islands appear (Hawaii)o Occurs also afer mass extinctiono Different lava flows separate species on the Hawaiian islands (ex:fruit flies)/the “silversword alliance” all five plants related to one ancestor  different on every island- Reproductive isolation o What times the organisms are active (nocturnal animals)o Food source preference (fruit flies prefer different fruits, will only meet potential mates on the same fruit)o Location- Reproductive Isolating Mechanismso Prezygotic: hinder mating+fertilizationo Postzygotic: hybrid not viable or not fertile as an adulto Examples of prezygotic  Habitat: land vs. water Temporal: active day vs. active at night/different mating seasons Behavioral: different songs/dances Mechanical: doesn’t work together Gametic: eggs+sperm don’t mix correctlyo Which is more common, pre or post? Prezygotic, because males have to spend a lot of energy courting females so this is selected against, trait to select the correct female and viable offspring is selected for- Same Species vs. New Specieso Based on the possibility/potential/likelihood for these matings must be considered when deciding whether this is a new specieso Steps: If the organisms can mate If the organisms can reproduce If the offspring is o …Then the organisms are of the same


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