Prin of Genetics exam 2 terminology

Independent Assortment

 two genes on two different homologous pairs of chromosomes

Linkage

two genes on a single pair of homologs; no exchange occurs, two genes on  single pair of homologs; exchange occurs between two nonsister chromatids

Complete Linkage

occurs when genes are on the same chromosome by very close together; segments of two nonsister chromatids are exchanged, but the linkage between the A and B alleles and between the a and b alleles is unchanged

Incomplete Linkage

segments of two nonsister chromatids are exchanged, and the alleles have recombined in two of the four gametes

During ___________ , the closer two genes are the less likely a genetic exchange will occur between them, lowers the frequency of recombinant gametes

Linkage Crossing Over

Standard Error

measures the accuracy of the sample mean

Standard Deviation

 expresses the variation around the mean in the original units of the measurement; the square root of the variance

Variance

 the average squared distance of all the measurements from the mean

Heritability

 the proportion of total phenotypic variation that can be attributed to genetic factors in a particular environment

3 Parts of Genetic Variation

1. additive variance

2. _________

3. interactive variance

dominance variance

Narrow Sense Heritability

proportion of phenotypic variation due to the additive genetic variance

When choosing between selection for broad or narrow sense heritability, choose ______

narrow

Heritability tends to be _____ for quantitative traits that are essential to survival

low

Traits that are less critical to survival, have _____ heritability bc more genotypic variation is present in the population 

higher

Population Genetics

examines the frequency, distribution, and inheritance of alleles within a population

Population

group of individuals belonging to the same species that live in a defined geographic area

Gene Pool

 the genetic information carried by members of a population

Most populations have a high degree of genetic _________ even though that may not be apparent with the phenotype

variability

The __________ that states that the frequencies of alleles and their respective genotypes in a population will _______ ______ unless acted upon by non-Mendelian processes 

population genetics theorem, remain constant

Selection

occurs when individuals with a particular genotype enjoy an advantage in survival or reproduction over another genotype

Fitness

an individual organisms genetic contribution to future generations

Directional Selection

traits at one end of a spectrum of phenotypes present in a population become selected for or against, usually as a result of changes in the environment 

Stabilizing Selection

selection for intermediate phenotypes, with those at both extreme ends being selected against

Disruptive Selection

selection against intermediate phenotypes and selection for both phenotypes at the extremes (bimodal disruption)

Migration

individuals move between populations

What 3 ways can genetic drift arise from?

1. Small population size 2. Genetic bottleneck 3. Founder effect

Genetic Bottleneck

develop when large populations undergo a drastic but temporary reduction in population size/numbers

Founder Effect

occurs when populations arise from a small number of individuals