17.2-Evolution as Genetic Change In Populations

less chance of genetic drift

in a large population

gene flow

movement of alleles from one population to another

List three sources of genetic variation

mutations, genetic recombination in sexual reproduction, and lateral genetic transfer

Population

A group of individuals that belong to the same species and live in the same area

Species

A group of similar organisms that can breed and produce fertile offspring.

no natural selection

A population that satisfies the conditions of the Hardy-Weinberg principle will experience.

What is a single gene trait, what is a polygenic trait

A trait controlled by only one gene, a polygenic trait is a trait of two or more genes

Cladogram

Diagram that shows the evolutionary relationships among a group of organisms

If a trait had no effect on an organism's fitness, what would likely happen to the allele for that trait?

Fewer copies of the allele would pass to future generations and the allele could even disappear completely from gene poo

directional selection

Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve

behavioral isolation

Form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding

What is speciation?

Formation of new species

Define gene pool and allele frequency

Gene pools are a consistency of all genes and allele frequency's are the number of times a gene appears in a pool.

What are the 3 sources of genetic variation in a population

Genetic, Behavioral, and temporal

If a trait made an organism less likely to survive and reproduce, what would happen to the allele for that trait?

It increases genetic variation- Fewer copies of the allele would pass to future generations and the allele could even disappear completely from gene pool.

Immigration/Emigration

One important factor in population growth- when animals move into an area or leave one.

crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

reproductive isolation

Separation of species or populations so that they cannot interbreed and produce fertile offspring

lateral gene transfer

The transfer of genes from one species to another, common among bacteria and archaea.

Explain why reproductive isolation must occur for separate population of the same species to evolve into different species

because the genes need to be switched up in order to have change in other species

Big-beaked finches that prefer to mate with other big-beaked finches are ____ isolated from small-beaked finches living on the same island

behavioral

list three ways that reproductive isolation occurs

behavioral isolation, geographic isolation, temporal isolation

founder effect

change in allele frequencies as a result of the migration of a small subgroup of a population

genetic evolution

change in gene (allele) frequency in a breeding population

developmental genes

control development of multicellular organisms

stabalizing selection

favors average version of the trait

peter and rosemary grant spent years on the Galapagos Island studying changes in_____populations

finch

geographic isolation

form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water

temporal isolation

form of reproductive isolation in which two populations reproduce at different times

small in size

genetic drift is most likely to occur in populations that are

Genotype

genetic makeup of an organism

What types of reproductive isolation may have been important in Galapagos finch speciation

geographic, behavioral, and ecological

The population of finches on a separate island are___________isolated from one another by large stretches of open water

geographically

How does mutation affect genetic variation

increases genetic variation

How does natural selection effect a single gene trait

it could change the phenotype frequencies

genetic equilibrium

situation in which allele frequencies remain constant

what must happen in order for a new species to evolve

some type of mutation must happen in the gene pool

the ancestors of the Galapagos Island finches originally came from the continent_________

south america

When individuals near the center of a curve have higher fitness than the individuals at either end of the curve, it is an example of

stabilizing selection

Speciation

Formation of new species

bottleneck effect

A change in allele frequency following a dramatic reduction in the size of a population

genetic drift

A change in the allele frequency of a population as a result of chance events rather than natural selection.

sexual selection

A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.

Phylogenic Tree of Life

Bacteria, Archaea, Eukaryota

Microevolution

Change in allele frequencies in a population over generations.

Define evolution in genetic terms

Evolution can be defined as a change in the relative frequency of alleles in the gene pool of a population.

Macroevolution

Evolutionary change above the species level.

Evolution vs. Genetic Equilibrium

allele frequencies remain constant

What determines the number of phenotype for a trait

depends on how many genes control the trait

What five conditions are necessary to maintain genetic equilibrium?

nonrandom mating, small population size, immigration or emigration, mutation, natural selection

Many finch characteristics appear in bell-shaped distributions typical of __________ traits

polygenic

Hardy-Weinberg Principle

principle that allele frequencies in a population should remain constant unless one or more factors cause the frequencies to change

Hox genes

series of genes that controls the differentiation of cells and tissues in an embryo

law of independent assortment

the law that states that genes separate independently of one another in meiosis

what does it mean for two species to be reproductively isolated from one another.

they are in two different places

When does geographic isolation occur?

two populations are seperated by geographic barriers such as rivers, mountains, or bodies of water

Define genetic drift

variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce.

When does behavioral isolation occur?

when populations are capable of interbreeding but have differences in courtship rituals or other types of behavior

What is geographic isolation?

when two populations are separated by geographic barriers

disruptive selection

which type of selection is most likely to create two distinct phenotypes