Upgrade to remove ads
Only $35.99/year

Bio 181 Microevolution

Terms in this set (40)

Modern evolution synthesis
integrates Darwinian evolution and Mendelian genetics
1. Integration of ideas from a variety of fields
2. Didn't change Darwins theory just expanded it.
Genotype
the genetic makeup of a trait (set of alleles) of an organism.
Phenotype
physical or physiological (biochemical) manifestation of the genotype. (color)
Gene
a discrete unit of heredity
Alleles
variants of the same gene
Dominant Allele
one allele determines phenotype in heterozygotes
recessive allele
an allele that does not determine phenotype in presence
of dominant allele
Microevolution
changes in heritable traits (determined by allele frequencies) in a
population over generations. The frequencies of alleles changing over time.
Genetic variation
substrate for natural selection
Genetic variation 2 main kinds
1. Mutation
2. Recombination
Mutation
Random change in the genetic code: Ultimate (original) source of variation
1. changes in nucleotide sequences
2. chromosomal mutations
Types of mutations
insertion, deletion, substitution
Genetic recombination
sexual reproduction
Polymorphism
a character within a population that is represented in
two or more forms (morphs)
Population genetics
field of biology studying the genetic variation within populations and the processes actin on them
Population
a group of interbreeding individuals of the same species that are occupying a
given area
Gene pool
collection of genetic material shared by all members of a population
Allele frequency
proportion of a population's gene pool consisting of a specific
allele
Evolutionary mechanisms
forces that change genetic structure of a population
5 evolutionary mechanisms
1. mutation
2. genetic drift
3. gene flow
4. selection
5. non-random mating
Genetic drift
a random change in a population's allele frequency due to chance (dumb luck) (affects small populations)
Fixation
only one kind of allele remains in a population at a given locus (a locus is the location on the chromosome where the gene is)
Bottleneck effect
drastic reduction in population size
Founder effect
a small representative of a larger population "founds" a
new population isolated from parent population
Gene flow
genetic exchange due to movement of individuals between populations
Fitness
contribution of a phenotype to future generations relative to
contributions of other phenotypes.
Sexual selection
form of selection in which certain traits are advantageous
in acquiring mates
Homogenize populations
individuals moving between populations. can be positive and negative.
Natural selection
results in adaptation and fitness
Fitness
contribution of a phenotype to future generations relative to
contributions of other phenotypes.
3 forms of fitness
1. stabilizing selection
2. directional selection
3. disruptive selection
Stabilizing selection
preserves average characteristics by favoring
average individuals
Directional selection
changes characteristics of a population by favoring
individuals that vary around one of the extremes. A shift in a trait to a preferred phenotype. One extreme is favored.
disruptive selection
changes characteristics of a population by favoring
both extremes.
intrasexual selection
compete for access to mates
intersexual selection
mate choice
Neutral mutations
unaffected by natural selection
sexual recombination
increase number of possible genotype
frequency-dependent selection
fitness of a phenotype dependent on its frequency in a population
heterozygote advantage
maintains polymorphic loci
Sets found in the same folder