Lab 1: Evolution and Population Genetics Flashcards
List the 4 agents of Evolution
Natural Selection
Genetic Drift
Gene Flow
Mutation
Name the 2 most important of the 4 Agents of Evolution
Natural Selection and Genetic Drift
Genetic Drift
A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next.
Types of genetic drift include the founder effect and the bottleneck effect.
Are the effects of genetic drift are most pronounced in small or large populations?
SMALL
Gene Flow
The transfer of alleles from one population to another, resulting from the movement of fertile individuals or their gametes.
Gene Flow = immigration/emigration
Hardy-Weinberg Principle
The principle that frequencies of alleles and genotypes in a population remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work.
A null model.
What are the 5 conditions for the Hardy-Weinberg Principle
- The Population size must be Infinitely Large.
- The Population is isolated from Gene Flow with other population (i.e., No Immigration or Emigration).
- There is no net Mutation.
- Individuals Mate Randomly
- No Natural Selection occurs
Natural Selection
A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.
Genotype
The genetic composition, or set of alleles, of an organism.
Phenotype
The observable physical and physiological traits of an organism, which are determined by its genetic makeup. The expression of the genotype is influenced by the environment.
Founder Effect
Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population.
Bottleneck Effect
Genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions. Typically, the surviving population is no longer genetically representative of the original population.
Is Variation essential for Evolution?
Yes!!
Microevolution
Evolutionary change below the species level; change in the allele frequencies in a population over generations.
Macroevolution
Evolutionary change above the species level. Examples of macroevolutionary change include the origin of a new group of organisms through a series of speciation events and the impact of mass extinctions on the diversity of life and its subsequent recovery.
macroevolution=the evolution of species
Evolution
Descent with modification; the idea that living species are descendants of ancestral species that were different from the present-day ones; also defined more narrowly as the change in the genetic composition of a population from generation to generation.
Population
A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring.
Fitness
Fitness (often denoted w in population genetics models) is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment. In either case, it describes the ability to both survive and reproduce, and is equal to the average contribution to the gene pool of the next generation that is made by an average individual of the specified genotype or phenotype. The term “Darwinian fitness” is often used to make clear the distinction with physical fitness. If differences between alleles of a given gene affect Darwinian fitness, then the frequencies of the alleles will change across generations; the alleles with higher fitness become more common. This process is called natural selection.
An individual’s fitness is manifested through its phenotype. The phenotype is affected by the developmental environment as well as by genes, and the fitness of a given phenotype can be different in different environments. The fitnesses of different individuals with the same genotype are therefore not necessarily equal. However, since the fitness of the genotype is an averaged quantity, it will reflect the reproductive outcomes of all individuals with that genotype in a given environment or set of environments.
Inclusive fitness differs from individual fitness by including the ability of an allele in one individual to promote the survival and/or reproduction of other individuals that share that allele, in preference to individuals with a different allele. One mechanism of inclusive fitness is kin selection.
Survivability
?
Descent with Modification
Evolution
directional selection
Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.
disruptive selection
Natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes.
Stabilizing selection
Natural selection in which intermediate phenotypes survive or reproduce more successfully than do extreme phenotypes.
Many small changes in the gene pool of a population can lead to…
… the rise of a new species
When allelic frequencies change, what is occurring?
Evolution.
Do allelic frequencies change from generation to generation in diploid, sexually reproducing populations due only to sexual reproduction and recombination?
No
