1 Review Define genetic drift Relate Cause and Effect How can the founder effect lead to changes in the allele pool 2 Infer Genetic equilibrium is uncommon in actual populations. Why do you think this is the case 3 Evolution Do you think populations stay in genetic equilibrium after the environment Has changed significantly- explain.

Ch 17 Evolution of Populations 17.2 Evolution as Genetic Change in Populations

Insect populations often contain a few individuals that are resistant to a particular pesticide They pass on their resistance to their offspring and soon the pesticide-resistant offspring dominate the population.

Natural Selection on Single-Gene Traits Lead to changes in ______________________________________and then to evolution Mutation in one gene that determines body color in lizards can affect their lifespan The normal color for lizards is brown, a mutation may produce red and black forms.

Red lizards are more visible to predators They are less likely to survive and reproduce = red allele is _______________.

Black lizards can absorb sunlight Higher body temperatures may allow the lizards to move faster, escape predators, and reproduce.

Natural Selection on Polygenic Traits The fitness of individuals may vary from one end of the curve to the other Can affect the range of ______________________ and hence the shape of the ______________________________.

Directional Selection Individuals at ___________________of the curve have higher _________________ than individuals in the middle or at the other end Range of phenotypes _____________.

Stabilizing Selection Individuals near the _________________ of the curve have higher fitness than at either end Keeps the center of the curve at its current position, but it _____________________ the overall graph.

Disruptive Selection Individuals at the _________________________________________ ____of the curve have higher fitness than individuals near the middle Acts against the intermediate type and can create ____________ distinct phenotypes.

Genetic Drift _______________________________in allele frequency.

Genetic Bottlenecks Change in allele frequency following a _________________________________________ _________ in the size of a population A disaster may kill many individuals in a population, and the surviving population’s ________________________________ may contain different ___________________________________from the original gene pool.

The Founder Effect Allele frequencies change as a result of the _______________________ of a _______________________________________ of a population.

Genetic Equilibrium Allele frequencies in the population _________________________________________ _____________ __________________ is ____________ occurring.

Hardy-Weinberg Principle All conditions that must occur for evolution _______________________________________ Very ______________________ population No ___________________________ _______________________ mating No ____________________________ No _____________________________________.

Large Population _____________________________has less effect on large populations Large population size helps maintain genetic equilibrium.

No Mutations If mutations occur, __________________________ may be introduced into the gene pool, and _________________________________________ __________will change.

Random Mating All members of the population must have an _________________________________________ ___________ to produce offspring Individuals must mate with other members of the population at ________________________________________.

Random Mating Non random mating examples Selective breeding Self pollination Artificial selection Sexual selection

Sexual Selection Individuals in a population showing a ______________________for mating with a certain phenotype or trait.

Sexual Selection

No Migration (No Gene Flow) Individuals who join a population may _________________________________________ _______________ into the gene pool Individuals who leave may _________________________________________ _from the gene pool There must be no movement of individuals into or out of a population.

No Natural Selection All genotypes in the population must have _________________________________________ _____________ of surviving and reproducing No phenotype can have a _________________________________________ _____________ over another.

Shuffling of genes during sexual reproduction produces many _________________________________________ but does not alter the _________________________________________ _of alleles in a population.

1 Review What is geographic isolation Predict A newly formed lake divides a population of beetle species into two groups. What other factors besides isolation might lead to the two groups becoming separate species 2 Review What types of reproductive isolation may have been important in Galapagos finch speciation- explain Apply Concepts Explain how the vegetarian tree finch. Which feeds on fruit might have evolved

Ch 17 Evolution of Populations 17.3 The Process of Speciation

How does one species become two?

Speciation Formation of a new species Species- group of organisms that are similar enough to ____________________________________________ ___________________________________________.

Speciation Steps Part of population __________________and becomes ___________________________ _____________ prevents two groups from coming in contact with each other Groups ________________________ to their own environments Adaptations occur and add up until the two groups become ___________________where even if barrier is removed the groups do not _____________________.

Lion and Tiger

Polar Bear and Grizzly Bear

Reproductive Isolation _________________________ of one group to mate ________________________ with any other group.

Behavioral Isolation Two populations that are capable of interbreeding develop differences in _______________________ or ___________________________________.

Geographic Isolation Two populations are separated by _________________________________________ such as rivers, mountains, or bodies of water.

Temporal Isolation Two or more species reproduce at ________________________________________.

Speciation in Darwin’s Finches Founding of a new population Geographic isolation Changes in the new population’s gene pool Behavioral isolation Ecological competition.

Founders Arrive Many years ago a few finches (species M) arrived from ___________________ ___________________

Geographic Isolation The island had a unique environment Founder effect, geographic isolation, and natural selection resulted in a ___________________ ___________________ Species A.

Changes in Gene Pools Populations on each island ___________________ ___________ to local environments Two distinct populations evolved A and B.

Behavioral Isolation Some species B finches go back to first island Enough time has passed where the two species ___________________ ___________________ ___________________ _________________kee p them from mating.

Competition and Continued Evolution Species evolve in a way that increases the differences between them, and new species may evolve C, D, and E More specialized birds have ___________________ _____________for food.