1 Review Define the terms genes pool and relative frequency Predict Suppose a dominant allele causes...
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1 Review Define the terms genes pool and relative frequency Predict Suppose a dominant allele causes a plant disease that usually kills the plant before
1 Review Define the terms genes pool and relative frequency
Predict Suppose a dominant allele causes a plant disease that
usually kills the plant before it can reproduce. Over time what
would probably happen to the frequency of that allele in the
population 2 Explain How does genetic recombination result in
genetic variation Relate Cause and Effect Why does sexual
reproduction provide more opportunities for genetic variation than
asexual variation 3 Explanation Explain how mutations are important
in the process of biological evolution
Slide 2
CH 17 EVOLUTION OF POPULATIONS 17.1 Genes and Variation
Slide 3
Darwin developed his theory of evolution without knowing how
heritable traits passed from one generation to the next or where
heritable variation came from.
Slide 4
In genetic terms Evolution is the change in allele frequency of
a population over time.
Slide 5
Genotype and Phenotype in Evolution Natural selection acts
directly on phenotype, not genotype Some individuals have
phenotypes that are better suited to their environment than others,
produce more offspring and pass on more copies of their genes to
the next generation.
Slide 6
Gene Pool All the genes, including all the different alleles
for each gene that are present in a population.
Slide 7
Relative Frequency Number of times a particular allele occurs
in a gene pool, compared with the total number of times alleles for
the same gene occurs.
Slide 8
Natural selection operates on individuals Evolution operates on
populations.
Slide 9
Sources of Genetic Variation Mutation Genetic recombination
during sexual reproduction Lateral gene transfer.
Slide 10
Mutations Mutations that produce changes in phenotype may or
may not affect fitness Some lethal or lower fitness Some beneficial
and raise fitness Only matter if they can be passed from generation
to generation Must occur in the germ line cells that produce either
eggs or sperm.
Slide 11
Genetic Recombination in Sexual Reproduction Most heritable
differences are due to genetic recombination We have 23 chromosomes
Number of combinations 2 23 8.4 million combinations of each sperm
or egg.
Slide 12
Lateral Gene Transfer Occurs when organisms pass genes from one
individual to another that is not its offspring Can be same or
different species Think bacteria.
Slide 13
Single-Gene Traits Trait controlled by only one gene Just two
or three distinct phenotypes Most common form of the allele can be
dominant or recessive.
Slide 14
Polygenic Traits Traits controlled by two or more genes Each
gene of a polygenic trait often has two or more alleles Often has
many possible genotypes and even more different phenotypes.
