Transcript CH16
Evolution • Process where a species may change over time • Individuals w/traits better suited for their environment are more likely to survive – Organisms better suited tend to pass on traits – Survival of species and inherited traits are result of natural selection Darwin’s Travels Decent with modification Theory of Evolution by Natural Selection • Number of individuals that have “strong” traits will increase in a population – – – – Overproduction (more offspring than will survive) Variation (more than one form of trait) Selection (trait increase/decrease survival rate) Adaptation (trait increase survival will be more common) (txt uses differential reproduction) Natural Selection What Darwin Explained • Fossils – Pattern of gradual change from past to present • Biogeography – Similar environments shape organisms in similar ways • Developmental Biology – Development of embryos • Biochemistry and Anatomy Evidence of Whale Evolution transitional species Forelimbs of Vertebrates Homologous (same) and Analogous Structures (different) Darwin’s Strengths • Lots of data • Testable material • Showed that organisms changed – Evidence – Mechanism – Variation Darwin’s Theory Updated • Can an individual evolve? – Populations evolve when natural selection act on genes • Is evolution the survival of the fittest? – The “fittest” is not always formed, just those that “fit” well enough to have offspring • Is evolution predictable? – We cannot predict the exact path that evolution will take Natural Selection of Anole Lizard Adaptive Radiation Evolution at ALL Scales • Speciation (formation of new species) – Natural population that can interbreed and produce healthy fertile offspring – Also classified by their physical features, ecological roles, and genetic relationships • Microevolution • Macroevolution Microevolution • Inherited traits over time in a population – – – – – Natural selection Migration Mate choice Mutation Genetic drift • Hardy – Weinberg Principal (Genetic Change) Macroevolution • Patterns in which new species evolve – – – – – – Convergent evolution (strongly directed) Coevolution (organism involved) Adaptive Radiation (split into lineages) Extinction (fail to reproduce, die off) Gradualism Punctuated Equilibrium Natural Selection of Anole Lizard Adaptive Radiation Species Formation • Geography • Niche • Behavior and Timing of Mating • Hybridization • Polyploidy