GEN BIO 2 | Microevolution

Evolution

the change in the frequency of a gene in a population

Microevolution

the evolutionary change within population

Forces that Shift Gene Frequency

1. Natural selection

2. Mutation

3. Gene flow

4. Genetic drift

5. Non-random mating

Natural Selection

As members have variation in characteristics, the individuals that are adapted better to the environment are more likely to reproduce and survive. These advantageous genetic difference are heritable and become more common to the population

Variation

members of a population differ from one another

Increased Fitness

individuals that are better adopted to their environment are more likely to reproduce

Inheritance

The genetic differences are heritable

Types of Selection

1. Directional Selection

2. Disruptive Selection

3. Stabilizing Selection

Directional Selection

the extreme phenotype is favored and the frequency distribution curve shifts in that direction

Disruptive Selection

at least two extreme phenotypes are favored over intermediate phenotype, common in codominance

Stabilizing Selection

the intermediate phenotype is favored

Sexual Selection

adaptive changes in males and females that lead to an increased ability to secure a mate

Intrasexual Selection

The members of one sex compete among themselves to access to the opposite sex, meaning the strongest male are most likely to pass on their allele. This entails the female population is low.

Intersexual Selection

the members of one sex choose their mates from among the multiple individuals of the opposite sex, meaning the brightest males get the most opportunities to mate.

Mutation

a random change in the DNA sequence, which can serve as a new genetic variation, thought not all of these affect the genetic equilibrium, occurs during DNA replication

Gene Flow

the movement of alleles across populations, also known as migration; when it brings a new or rare allele into the population, the allele frequency changes

Genetic Drift

changes in the allele frequencies of a gene pool due to the chance events, such events remove individuals , and their genes, from a population at random without regard for genotype or phenotype.

Bottleneck Effect

the loss of genetic diversity due to natural disasters. disease, over-hunting, over-harvesting, or habitat loss

Founder Effect

genetic variation is lost when. few individuals break away from a large population to found a new population

Non-random Mating

it can affect how the alleles in the gene pool assort into genotypes

Assortative Mating

similar type of individuals mate more frequently with each other than those with a dissimilar type

Disassortative Mating

dissimilar type of individuals mate more frequently with each other than with a similar type