Chapter 11 “The Mechanisms of Evolution” w Section 11.1 “Darwin Meets DNA” Objective: Identify mutations and gene shuffling as the primary sources of inheritable variation.

Review w Inheritable traits: traits that are passed from one generation to the next. w Genes: carry info that determines traits w Genotype: genetic make-up w Phenotype: Physical, behavioral, and biochemical characteristic

Inheritable Traits w Since genes are the carriers of traits ---> then they are also the source of inheritable variation. w Two types: Mutations Gene Shuffling

Mutation w Change in a DNA sequence that effects genetic information. w Rate vary: Humans vs. Bacteria. w Reasons: mistakes during replication, radiation, chemicals w Can effect fitness (ability to survive)

Gene Shuffling w The possible combination of genes passed on from parents to offspring. w Results of sexual reproduction. w EX: deck of cards; same cards different hands.

Inheritable Variation w Visible: Color of flower petals. Size of humans. w Not Visible: Protein synthesis Enzyme action

Controlled Traits w Some are controlled by single genes (widow’s peak) some by several genes (height). w Single gene: 2 or 3 possible phenotypes. w Polygenic gene: Many phenotypes.

Natural Selection w Natural Selection acts on an organisms phenotypes not genotype. w Phenotype = the interaction between genotype & environment. w N.S. determines which alleles are passed on to the next generation.

Species w A group of similar individuals that can breed with one another and produce fertile offspring = population. w Separation of populations or species so they cannot interbreed is called reproductive Isolation.

Assignment w Outline 11.2

Review 11.1 w Two types of Inheritable Traits Mutation Gene Shuffling w Natural Selection Acts on Phenotype not Genotype. w Species, Population, & Reproductive Isolation. w Single-gene Traits vs. Polygenic Traits.

“Evolution as Genetic Change” 11.2 w Objective: Discuss the concept of Gene Pools. Define Evolution in terms of Genetics. Describe Speciation.

Gene Pool w “Pool” refers to a grouping of resources. w Entire collection of individual genomes in a population of organisms.

Evolution w Species do not evolve, but populations do. w Evolution is any change in the frequencies of alleles in a gene pool of a species.

Traits w Single-Gene Traits Harmful Helpful w Polygenic Traits Remember polygenic traits may produce many phenotypes. Directional, Stabilizing, & Disruptive.

Natural Selection on Polygenic Traits w Graphs of variation display a bell-shaped curve or normal distribution. w Fitness can vary from one end to another. w Nat. Sel. can affect distribution of curve.

“Other Mechanisms for Evolutionary Change” w Genetic Drift is a random change in allele frequency. w Less common w More likely to occur in smaller population.

Genetic Drift cont... w Small groups of organisms colonize a new habitat. w May carry different alleles than original population. w Genetically different species are produced.

Speciation (page 251) w The formation of a new species. w In order to occur, species must evolve enough genetic changes (by N.Sel.)so inbreeding cannot occur.

The Pace of Evolution w Evolution occurs as a result of Natural Selection & Genetic Drift. w Gradualism = is the idea that evolution occurs slowly. w Punctuated Equilibrium = long periods of stability followed by interrupted periods of rapid change.