BIOLOGY NOTES EVOLUTION PART 2 PAGES 326-346

Standards: 6.3 ____ Describe how mutation and genetic recombination increases genetic variation ____ Describe how biological diversity is increased by the origin of new species and how it is decreased by the process of extinction ____ Discuss mechanisms of evolutionary change other than natural selection such as genetic drift and gene flow ____ List the conditions for Hardy-Weinberg equilibrium in a population and why these conditions are not likely to appear in nature. Use the Hardy-Weinberg equation to predict genotypes in populations from observed phenotypes 6.4 6.5 6.6

Essential Question: 1. What mechanisms have allowed for diversity in organisms?

I. Evolution & Genetic Frequency The study of evolution was able to advance in the 1930’s with the work of _______ and his theories of ___________. Scientists were able to confirm the _____ was the unit of inheritance for all organisms With the work of genetics, scientists were able to express __________ as a force that action upon genetic _________ within a ___________ Mendel inheritance gene evolution variation population

What process allows for new genes to appear within a group? _________ What process allows the reshuffling of genes to occur in order to produce new phenotypes? __________________ MUTATIONS AND SEXUAL REPRODUCTION INCREASE GENETIC VARIATION WHICH IS WHAT EVOLUTIONS ACTS UPON!!! mutation sexual reproduction

A. Genetic Variation and Evolution Gene pool = all the variations of genes present within a __________ Population = a group of individuals of the same ________ that __________ and live in the same environment. population species interbreed

Gene Frequency = the number of times an ______ occurs within a population e.g. In a rabbit population, if B (Black) has an allele frequency of 60% and b(brown) has an allele frequency of 40%, what percentage of the population have genotypes that are: a. Homozygous Black?_____ b. Homozygous brown?_____ c. Heterozygous Black?_____ allele 36% BB = .60 x .60 16% bb = .40 x.40 48% Bb and bB = (.60 x .40) x 2

If over time the allele frequencies are _________ then we say the population is in ________ equilibrium and ____ evolution is occurring Hardy-Weinberg Principle = allele frequencies in a __________ will remain constant unless one or more factors cause those frequencies to _______ constant genetic NO population change

a. Conditions Necessary for Genetic Equilibrium (NO EVOLUTION): 1. Random mating if there is preferential mate selection, certain alleles would become more __________ 2. Large population large populations ensure there is a less noticeable effect by _______ drift 3. No mutations mutations could introduce ____ alleles into a population prominent genetic new

4. No Migration (____________ or __________) individuals coming ____ a population could introduce new alleles while individuals _______ a population may eliminate alleles 5. No Natural Selection all __________ must have an equal chance of ________ this implies that the environment must remain relatively _________ immigration emigration into leaving genotypes survival constant

GENTIC EQUILIBRIUM IS HIGHLY UNLIKELY WHICH MEANS EVOLUTIONS MUST OCCUR!!!! Using Hardy-Weinberg equations it can be proven that over time (generations), if there are changes in the frequency of alleles for a population, then we say the population is ________ or changing evolving

B. HOW Populations Evolve (Sources of Evolutionary Change): a. Natural Selection: when _______ selects the best ________ individuals to survive If the ____________ changes, then nature will select new individuals and the ______ frequency for a given population will change e.g. nature adapted environment allele dinosaurs & the meteor

2. Genetic Drift = evolution that occurs because of random changes in ______ frequencies that occur in ______ populations In small populations, individuals that carry a particular ______ may by chance have more offspring that inherit the ______ over time, this could cause that particular ______ to be present in a population at a _______ frequency which, overall, changes the population dynamics allele small allele allele allele higher

In a ______ population this would be less noticeable larger

Genetic drift, however, decreases genetic _________ because it makes small populations genetically _________ which means these populations are less likely to experience _______ selection variation identical natural

bottleneck effect = genetic drift that occurs because an ______ lessens the overall population founder effect = genetic drift that occurs because a small number of __________ colonize a new area event individuals

c. Gene Flow = evolution that occurs when individuals ________ into another population and introduce new _______ into that population This __________ the genetic _________ of a population (opposite of _______ drift in terms of genetic variation) Neighboring populations can begin to look _______ migrate alleles increases variation genetic similar

If there is no gene flow, and populations become ________ from one another, speciation may occur this occurs because each population is now independently subject to _________ and genetic _____ speciation = the rise of two or more ________ from one existing species isolated mutations drift species

Eastern vs. Western Meadowlark Populations

d. Non-random mating: choosing specific _______ due to ___________ i.e. mates preference polydactylism

C. Possible Outcomes of Evolution Convergent Evolution = evolution toward similar _________ in unrelated species due to a similar environment i.e. anatomy shark vs. dolphin tails

b. Divergent Evolution = evolution toward dissimilarity of _________ within closely related species due to varying ______________ i.e. anatomy environments kit fox vs. red fox

c. Co-Evolution = two or more species evolving in _________ to each other d. Extinction e. Speciation response