Shaping Evolutionary Theory

Front 1

Evolution

Back 1

Change in the genes of a species over time; changes in allelic frequencies over time

Front 2

Conditions for Evolution

Back 2

Genetic Drift, genetic flow, mutation, non random mating, natural selection

Front 3

Equilibrium

Back 3

Allelic frequencies are constant; all conditions must be fulfilled or evolution will take place; difficult to maintain

Front 4

Conditions for equilibrium

Back 4

No genetic drift, no gene flow, no mutation, random mating, no natural selection

Front 5

Genetic Drift

Back 5

A change in allelic frequencies due to chance; disaster, disease; large populations keep more consistent allelic frequencies

Front 6

Founder Effect

Back 6

Alleles that are uncommon in the general population are common in a small, isolated population

Front 7

Bottleneck

Back 7

A population shrinks for a while then rebounds with less diversity; leaves only the alleles of the survivors in the new, growing population

Front 8

Gene Flow

Back 8

New genes entering the population (immigration); allows a new frequency of alleles; may introduce new alleles; difficult to prevent

Front 9

Nonrandom mating

Back 9

Random mating rarely occurs; mating practices are usually influenced

Front 10

Mutation

Back 10

Random changes in DNA; accumulation of mutations changes allelic frequencies and introduces new alleles

Front 11

Natural Selection

Back 11

Leads to changes in allelic frequencies in a species over time. To maintain equilibrium and prevent natural selection, all individuals must be adapted to their environment.

Front 12

Stabilizing Selection

Back 12

Increases the average phenotype; eliminates the extreme phenotypes

Front 13

Directional Selection

Back 13

A specific phenotype makes an organism more fit so it increases; increases extreme phenotype while eliminating all others

Front 14

Disruptive Selection

Back 14

Splits population into two groups; increases both extremes; eliminates average individuals

Front 15

Sexual Selection

Back 15

Increases attractive genes; eliminates unfavorable genes

Front 16

Reproductive Isolation

Back 16

Preventing gene flow between two populations

Front 17

Species

Back 17

Organism that is reproductively isolated from other organisms

Front 18

Prezygotic Isolation Mechanisms

Back 18

Temporal- mating at different times. Geographical- separated by barriers. Behavioral- having different mating behaviors. Biochemical/ chromosomal- sperm and egg not compatible. Structural- reproductive organs are not compatible.

Front 19

Prezygotic Isolation Mechanisms

Back 19

Temporal- mating at different times. Geographical- separated by barriers. Behavioral- having different mating behaviors. Biochemical/ chromosomal- sperm and egg not compatible. Structural- reproductive organs are not compatible.

Front 20

Postzygotic Isolation Mechanisms

Back 20

After fertilization, the new organism cannot reproduce; sterile offspring are created

Front 21

Prezygotic Isolation Mechanisms

Back 21

Temporal- mating at different times. Geographical- separated by barriers. Behavioral- having different mating behaviors. Biochemical/ chromosomal- sperm and egg not compatible. Structural- reproductive organs are not compatible.

Front 22

Postzygotic Isolation Mechanisms

Back 22

After fertilization, the new organism cannot reproduce; sterile offspring are created

Front 23

Allopatric Speciation

Back 23

Separates by geographic barriers

Front 24

Sympatric Speciation

Back 24

Not separated by geographical barriers; usually plants and insects; organisms fill different niches in the same ecosystem.

Front 25

Divergent Evolution

Back 25

The same as adaptive evolution; one common ancestor gives rise to many different species; indicates by homologous structures.

Front 26

Coevolution

Back 26

Species developing close relationships with one another over time; mutualism, commensalism, parasitism, mimicry, predator-prey

Front 27

Coevolution

Back 27

Species developing close relationships with one another over time; mutualism, commensalism, parasitism, mimicry, predator-prey

Front 28

Convergent Evolution

Back 28

Different species evolve similar traits even though they don't share a RCA. Similar environments can drive this type of evolution.

Front 29

Coevolution

Back 29

Species developing close relationships with one another over time; mutualism, commensalism, parasitism, mimicry, predator-prey

Front 30

Convergent Evolution

Back 30

Different species evolve similar traits even though they don't share a RCA. Similar environments can drive this type of evolution.

Front 31

The Theory of Endosymbiosis

Back 31

Mitochondria are descendants of aerobic archaebacteria; chloroplasts are descendants of photosynthetic archaebacteria.