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HUMAN BIOLOGY - Evidence of evolution > Natural selection > Flashcards

Flashcards in Natural selection Deck (11)
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1

Gene flow

the movement of genetic material from one population to another

2

Migration

when an individual moves between populations, they enable gene flow

3

Barriers to gene flow

Geographical barriers
Sociocultural barriers

4

Natural selection

process by which species become better adapted to an environment. Most favorable characteristics survive.

5

Process of Natural selection

1. Variation; the differences that exist between individuals or populations of a species. allows for the advantageous alleles to arise.

2. Overproduction; when more of a species if born than ultimately survive. e.g. The turtles

3. Selection; aka survival of the fittest, this occurs when species with the more advantageous allele are more likely to survive causing the allele to become more frequent in the gene pool. (Selective agents)

4. Reproduction; in order for a species to survive, they must reproduce to pass on their favorable characteristics.

5. The favorable characteristics are more likely to be passed on and arise in a population/species

6

Genetic drift

The random, non-directional change in allele frequency between generation. Genetic drift is not affected by whether an allele is beneficial or harmful; instead it is purely by chance. occurs in all sizes of population.

7

Founder affect

occurs when a small group moves away from its home land to a totally new area and establishes a population

Can cause a new group to have;
- different allele frequent from the original population
- decrease in genetic frequency

8

Bottleneck effect

when an event such as a natural disaster severely reduces the size of the population.

- The allele frequency after the disaster may be different from before the event

9

Speciation

Describes the evolutionary processes that lead to the formation of a new species.

10

Species

a group of individuals that share many characteristics are are able to interbreed under natural conditions to produce fertile off spring.

11

Steps of speciation

1. Variation; There is a variation between individuals of a species
2. Isolation; Populations of same species are isolate without gene glow
3. Selection; Each population is subjected to different selective agents
4. Speciation; the allele frequency changes until they become so different that the two groups are no longer able to interbreed