Variation and mutation

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Slide 1

Evolutionary Concepts: Variation and Mutation

Slide 2

Definitions and Terminology

Microevolution

Changes within populations or species in gene frequencies and distributions of traits

Macroevolution

Higher level changes, e.g. generation of new species or higher–level classification

Slide 3

Gene

Section of a chromosome that encodes the information to build a protein

Location is known as a “locus”

Slide 4

Allele

Varieties of the information at a particular locus

Every organism has two alleles (can be same or different)

No limit to the number of alleles in a population

Slide 5

Zygosity

Homozygous:

Two copies of the same allele at one locus

Heterozygous:

Two different alleles at one locus

Slide 6

Genotype

Genetic information contained at a locus

Which alleles are actually present at a locus

Example:

Alleles available: R and W

Possible genotypes:

RR, RW, WW

Slide 7

Phenotype

Appearance of an organism

Results from the underlying genotype

Slide 8

Phenotype

Example 1:

Alleles R (red) and W (white), codominance

Genotypes: RR, RW, WW

Phenotypes: Red, Pink, White

Slide 9

Phenotype

Example 2:

Alleles R (red) and w (white), simple dominance

Genotypes: RR, Rw, ww

Phenotypes: Red, Red, white

Slide 10

Dominant and Recessive Alleles

Dominant alleles:

“Dominate” over other alleles

Will be expressed, while a recessive allele is suppressed

Recessive alleles:

Alleles that are suppressed in the presence of a dominant allele

Slide 11

Gene Pool

The collection of available alleles in a population

The distribution of these alleles across the population is not taken into account!

Slide 12

Allele frequency

The frequency of an allele in a population