1. BIOLOGY NOTES EVOLUTION PART 2 PAGES 326-346

2. 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

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

4. 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

5. 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

6. 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

7. 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

9. 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

10. 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

11. 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

12. 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

13. 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

16. 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

18. In a ______ population this would be less noticeable
larger

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

20. 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

21. 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

22. 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

23. Eastern vs. Western Meadowlark Populations

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

25. 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

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

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