Natural Selection and Evolution

Evolution Darwin Late 1800s Historical View of Earth and its organisms. HMS Beagle Galapagos Islands Mechanism of Evolution is Natural Selection. Important Terms Species Population Community Gene Pool Allele Frequency Genetic Equilibrium Hardy Weinberg Equilibrium

Evolution: Requirements for Evolution—A change in the allele frequency of a population over time. Requirements: 1. Genetic Variability— may come from mutations and immigration. 2. More offspring are produced than can survive (due to limited resources, predation, etc…) 3. Some organisms must be better adapted than others. 4. There must be differential reproduction rates due to the adaptive characteristics of some members. Fitness Fecundity

Hardy-Weinberg Equilibrium Genetic Equilibrium Hardy-Weinberg Law Defined evolution by describing when it would not happen. There are 5 requirements that must be met for genetic equilibrium to occur. Requirements 1. No mutations. 2. No immigration or emigration. 3. There must be a very large population in order to avoid genetic drift. 4. There must be no natural selection. 5. There must be no sexual selection.

Hardy-Weinberg Equilibrium Important Terms Gene flow Genetic Drift The Founder Effect Ellis-van Creveld Syndrome Natural Selection Sickle Cell example Sexual Selection Non random Mating Natural Selection Patterns 1. Stabilizing—birth weight. 2. Directional—peppered moths; DDT resistance 3. Disruptive— swallowtail; mimicry example. Dimorphism or polymorphism

More on Evolution Inbreeding Dangers Cheetahs Pure bred dogs Microevolution Macroevolution Speciation Biological Species Concept Reproductive Isolating mechanisms Prezygotic Post Zygotic

Types of Speciation Phyletic—gradualism. Allopatric—separation by a physical barrier. Parapatric—Occurs in adjacent populations due to local environment problems. Plants and barbed wire example Sympatric— individuals continue to live with each other. Mostly in plants. Due to polyploidy. Hybridization

Patterns of Evolution Divergent Evolution— Share a common ancestor, but evolve differently. Adaptive Radiation Why does it occur? Convergent Evolution— become more alike due to environment. Aquatic mammals and fist. Parallel Evolution— Related species remain relatively the same due to their environments. Coevolution—Plants and pollinators; parasites and hosts.

More on Evolution Extinction Gradualism Punctuated Equilibrium Adaptive Radiation Why does this pattern occur?

Proof for Evolution Homologous features Analogous features Vestigial organs Fossil Record Radioactive Dating Comparative Embryology Comparative Biochemistry and Molecular Biology Artificial Selection

Origins of the World and Life Big Bang Theory Characteristics of the Pre-life world Oparin’s hypothesis Membrane Invagination Hypothesis Endosymbiotic Hypothesis Phylogenetics