Download Notes Unit 5 Part 2

BIOLOGY NOTES
EVOLUTION PART 2
PAGES 326-346
NAME:
DAY / MOD:
DATE:
Standards:
____ 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 population from
observed phenotypes
Essential Question:
1.
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 acts upon
genetic _________________ within a given ___________________
 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 EVOLUTION ACTS UPON!!!
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.
 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?___________
 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 _________________
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
4. No Migration (________________ or ___________________)
 individuals coming _________ a population could introduce new alleles while individuals
________________ a population may eliminate alleles
Range, A.
Unit 5 Page 2B
5. No Natural Selection
 all _________________ must have an equal chance of ________________
 this implies that the environment must remain relatively ______________
GENTIC EQUILIBRIUM IS HIGHLY UNLIKELY WHICH MEANS EVOLUTION 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
B. HOW Populations Evolve (Sources of Evolutionary Change):
a. Natural Selection: evolution that occurs 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
i.e.
b. 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
 In a ____________ population this would be less noticeable
 Genetic drift, however, decreases genetic _____________________ because it makes small
populations genetically ________________ which means these populations are less likely to
experience ________________ selection
 bottleneck effect = genetic drift that occurs because an ___________ lessens the population
 founder effect = genetic drift that occurs because a small number of ______________ colonize a
new area
c. Gene Flow = evolution that occurs when individuals ___________________ into another population
and introduce new ________ into that population
 This __________________ the genetic __________________ of the population (opposite of
______________ drift in terms of genetic variation)
 Neighboring populations can begin to look ______________
 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
d. Non-random mating: choosing specific ____________ due to ___________________
i.e.
C. Possible Outcomes of Evolution
a. Convergent Evolution = evolution toward similar ______________________ in unrelated species due
to a similar environment i.e.
b. Divergent Evolution = evolution toward dissimilarity of _______________ within closely related
species due to varying ___________________ i.e.
c. Co-Evolution = Two or more species evolving in _______________ to each other i.e.
d. Extinction
e. Speciation
STUDENT SYNTHESIS
To demonstrate knowledge of the information contained within these notes, within the space below EITHER 1. Create two
higher level test questions and answers based on the information OR 2. Write a comprehensive summary of the information
Range, A.
Unit 5 Page 2B