Torpey White

 Natural selection- a process in which organisms with certain inherited characteristics are more likely to survive.  Natural election acts on individuals, but populations evolve.  Evolution is caused by genetic variation.

 Microevolution- changes in allele frequencies over generations.  Mutations and sexual reproduction contribute to variations in individuals in a population.

 Gregor Mendel- theorized that traits were passed on through genes  Traits differ from person to person.  Genotypic properties are passed down, not phenotypic.

 Heritable variation is caused by the passing of quantitative characters.  Quantitative characters- heritable features in populations that vary based on environmental factors and multiple genes accounting for one phenotypic expression.  Measured with average heterozygosity- the average percent of loci that are heterozygous.  Cline- gradual changes of phenotypes that changes with geography

 geographic variation- differences in the genetic composition of separate populations.  Mutations alter genes and in turn alters phenotype. Can be a positive or negative mutation.  Mutations occur at random.  Point mutation- the change of one base in a sequence  Large mutations are usually harmful.

 Variation in populations that reproduce sexually results from the combinations of genes between parents.  This variation is caused by shuffling, crossing over, independent assortment, and fertilization.

 Population- localized group of individuals that are capable of having viable offspring  Gene pool- the compiled genetic information of a population  Hardy Wein-berg problems deal with allele frequencies in populations.  640 red flowers in a population of 1000, frequency of allele would be.8

 Used to study the genetic makeup of a population that is not evolving.  Used to track evolution.  5 conditions need to be met  No mutations  Random mating  No natural selection  Extremely large population  No gene flow

 Genetic drift- flocculation of gene frequencies from one generation to the next.  Genes can be lost randomly through genetic drift.  Two types of genetic drift  Founder effect  Bottleneck effect

 Founder effect- when a few individuals become isolated from a larger population  Gene pool of smaller group is normally not representative of the larger population.

 Bottle neck effect- when a drastic change in environment reduces the gene pool of a population  Same results as the founder effect

 Gene flow- the movement of alleles among populations  Alleles are transferred through gametes  Gene flow makes populations more similar  Gene flow is more likely to cause variation than a mutation

 “Survival of the fittest” is misleading, implies that natural selection is a direct competition.  Natural selection is caused by sexual reproduction, not competition.  Relative fitness- contribution one individual makes to the next generation. How effectively they passed on their genes.

 Directional selection- selecting at one end of the phenotypic range  Disruptive selection- selecting at both ends of the phenotypic range  Stabilizing selection- selecting in the middle of a phenotypic range

 Sexual selection- a form of natural selection where mates are picked for exhibiting specific traits  Sexual dimorphism- marked differences between sexes.  Intrasexual selection- individuals competing for mates. Male v male or female v female  intersexual selection- individuals chose mates vs. competing.

 Female frogs preferred long calls over short calls. The genetic makeup of the genes for calls were compared. Info for short calls was put with eggs that had long call info. It was shown that lc individuals had a better chance for survival. They concluded lc gene allowed for better survival.

 Balancing selection- when natural selection maintains two forms in a population.  Includes heterozygous advantage  Heterozygous advantage- when heterozygotes have a greater fitness than either homozygote.

 Frequency dependant selection- when the fitness of an allele declines when it becomes too popular.

 In a population of moose, lime green fur is dominant over orange fur. Out of 500 individuals, 370 have, and are homozygous for, lime green fur. Calculate the frequency of each allele and estimate the number of individuals who are heterozygous and homozygous recessive.