Unit 2 - Evolutions of Populations Flashcards
Trait/Character
heritable feature that varies among individuals
Discrete Traits
controlled by one or two genes; classified into types/groups (i.e flower color)
Quantitative Traits
controlled by multiple genes, phenotype falls on a continuum of values (i.e. height)
Homozygous
organism with two of the same alleles controlling character expression
Heterozygous
organism with two different alleles controlling character expression
Dominance
determines phenotype based on which allele is expressed when different alleles occur together
Dominant/Recessive
only when dominant is observed
Incomplete Dominance
intermediate of two phenotypes observed
Co-Dominance
Both phenotypes expressed
Norm of Reaction
refers to the expression of phenotype being dependent on genotype suitability in its environment; natural selection
Population
group of interbreeding individuals of same species
Gene Pool
genetic variation in a population
Microevolution
change in allele frequencies in population over generations
Hardy-Weinburg Principle
allele, genotype
frequencies will remain
constant when only
Mendelian segregation,
recombination are working
Directional Selection
individuals on one extreme of phenotype range have higher fitness (one best solution)
Disruptive Selection
individuals on both extremes of phenotype range have higher fitness than individuals in middle
Stabilizing Selection
individuals with intermediate phenotype have higher fitness than individuals on extremes
Balancing Selection
natural selection preserves two or more forms in population
Heterozygote Advantage
heterozygous genotype has a higher relative fitness than either the homozygous dominant or homozygous recessive genotype
Frequency-Dependent Selection
which phenotype is favored by selection
depends on how common it is
Macroevolution
broad changes that occur at or above species level; applies mainly to the evolution of whole taxonomic groups over long periods of time
