Ecology and evolution notes
Ecology and evolution notes Bio 181
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This 4 page Class Notes was uploaded by Robert Notetaker on Saturday March 12, 2016. The Class Notes belongs to Bio 181 at Brigham Young University - Idaho taught by Dr. Holyoak in Winter 2016. Since its upload, it has received 14 views. For similar materials see Biology 181 in Biology at Brigham Young University - Idaho.
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Date Created: 03/12/16
What is a Species? Reproductive Model: Cannot be used universally. Relationship with common ancestry: Phylogenetic Pre-Zygotic: Pre something- Anything from egg and sperm seeing each other or from being formed Pre-Zygotic Barriers: Different kinds of places. Different kinds of habitats. Different seasons for reproductive time. Behavioral mating dances. Mechanical difficulties. Gametic isolation. Lock and key gametes do not match up and do not form zygotes. Post-Zygotic Barriers: Reduced Hybrid Viability-ability to live, Reduced Hybrid Fertility-can not reproduce, Hybrid Breakdown- over a couple of generations. Anything that prevents anything from reproducing Morphological species concept: Look like not always can reproduce. Phylogenetic: Allopatric: Separated from species and could form independent evolution. Sympatric- within our population. Mate Selection: Nondisjunction: separates together. Plants more than everywhere. 4 copies of chromosomes: Plants can be tetraploid and handle this better than animals. Allopoly: Allopolyploidy state: Chromosomes from one species are 2n, others 1n Artificial Selection: Non-Random breeding preferred traits Natural Selection: Best combination of traits. Environment variable. Natural Selection: Individuals adapted tend to leave the most offspring Theory: Explanation that has been tested and held up over time. Homologous Structures: Forelimbs of tetrapod vertebrates. Vestigial Structures: Structures that do not work anymore. Genetic Drift: shifts gene frequency, very small populations die, no opportunity to reproduce. Reproduction and which individuals reproduce. Random events. (Simulation data) Gene fixation one allele remains in population More reproductive events, more genetic diversity, with the Cheetahs. Bottleneck Effect: Big Population that somehow reduces in size. Smaller Population size, fewer alleles. Heavy Hunting. Gene Flow: People move and take their alleles with them. Individuals that survive have the right combination of traits. Pressures change. Natural Selection Three Ways: Directional selection: Causes the trait to shift. Color shifts, lighter to darker Disruptive Selection: Extreme Selections such as light and dark. Very few intermediates, either light or dark colors. Stabilizing Selections: Extremes on both ends. After world war two there was modern medicine… Birth rate is a narrow range and becomes wider and wider. Sexual Selection: Elephant Seal fights on the birthing beaches with other males. Intersexual: More colorful peacock that survived over time. Hypothesis is based on other things something there to base the idea. Theory: Rigorous testing without rejection. Law: Not a scientific explanation. Laws help us understand theories. Descent with modification only a theory: They are mistaken. Theory is as powerful as it gets. Weak and strong not right or wrong Evolution is loaded with truth. A hypothesis can become a theory. A theory cannot become a law. What is evolution? -Mutation -Time -Population adapting -Inheritance of genetic traits-generation Evolution can occur without mutation It takes generations for populations to change Specifically changes in allele frequencies in a population Being adapted to your current situation. Mosquitoes and DDT: Month 0- 4% only survived 8 months later: 45% had resistance 1 year: 77% survived Scala Naturae: (Scale of Nature) Natural Theology: (Creationism) (Intelligent Design) Non Scientific This requires a creator or designer. Empirical observation: How where when what? No why. Evolution by acquired traits: lamark Evolution by natural selection: Darwin
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