20 terms

Chapter 17 biology vocab

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Gene pool
Common group of genes.
Allele Frequency
Number of times an allele occurs in a gene pool, compared to the total number of alleles in that pool for the same gene.
Single-gene trait
A trait controlled by only one gene.
Polygenic traits
Traits controlled by two or more genes.
Directional selection
When individuals have higher fitness than on the middle or at the other end.
Stabilizing selection
When individuals near the middle of the curve have higher fitness.
Disruptive selection
When individuals at outer ends of the curve have higher curves than the middle.
Genetic drift
Random change in allele frequency.
Bottleneck effect
Change in allele frequency following a dramatic reduction of size of a population.
Founder effect
Allele frequencies change as a result of the migration of a small subgroup of a population.
Genetic equilibrium
Allele frequencies do not change.
Hardy-Weinberg principal
States that allele frequencies in a population should remain constant unless one or more factors cause those frequencies to change.
Sexual selection
Individuals select mates based on inheritable traits.
Species
Population or group of populations whose members can interbreed and produce fertile offspring.
Speciation
Formation of a new species.
Reproductive isolation
When a population has split into two groups changes in gene pools can not spread to the other and can no longer interbreed.
Behavioral isolation
Two species that can interbreed separate due to differences in courtship rituals or other behaviors.
Geographic isolation
When two species are separated by geographic barriers.
Temporal isolation
Two or more species reproduce at different times.
Molecular clock
Uses mutation rates in DNA to estimate the time that two species have been evolving independently.