Genetics&EvolLEC12 Flashcards
What does the Hardy-Weinberg theorem states?
Alleles frequencies in a gene pool will tend to remain constant from generation to generation.
What is the bottleneck effect?
Ex. Isolated walrus
A change in the environment that may drastically reduce the size of a population, changing the gene pool. Tends to reduce genetic variation.
What is the founder effect?
Ex. Polydactyly (6 fingers)
The occurance when a few individuals become isolated from a larger population, which can change it’s allele frequencies.
What is gene flow?
Ex. zoo gorillas
The movement of genes between populations that causes gain or loss of alleles. Tends to reduce differences between populations over time.
So that allele frequencies will not change, the Hardy-Weinburg equilibrium requires what?
A large population with random mating.
What causes population to change in response to their environment, and is the primary mechanism of evolution?
Natural selection!
It increases the frequencies of certain genotypes.
What is variation or polymorphism!?
The occurances in all species that is not always heritable.
What are genetic polymorphism?
The heritable components of characters
Geneticists measure the number of polymorphisms in a population by determining the amount of what in the genes?
Heterozygosity!
What is Heterozygosity
The percent of loci that are heterozygous in a population.
What is geographic variation that most species shows?
Ex. Two difference mice with different numbers of chromosomes
The differences between gene pools of separate populations.
Sometimes it occurs as a cline.
What is a cline?
Ex. Height of plants on mountains
Gradual change along a geographic axis.
What is natural selection?
What frequencies does it increase, causing them to do what?
It is simply the survival and reproduction of some individuals and not others.
“Reproductive success”
It increase the frequencies of certain genotypes, causing them to adapt to their environment over generations.
What is fitness?
The contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals.
