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27 Cards in this Set

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  • Back
What are the two types of isolating mechanisms?
Postzygotic and prezygotic.
What is involved in Postzygotic Isolation?
The embro formed when the two organisms mate is viable.The hybridcould be sterile. The hybrids breakdown, and cannot interbreed.
What is involved in Prezygotic isolation?
The animals cannot reach fertilization. This may be caused by ecological, behavioral, physical and biochemical differences (sperm and egg incompatible)
What are the two types of rates of speciation
Gradualism and Punctuated equilibrium.
What is involved in gradualism?
In gradualism, change occurs in small increments, gradually building up and is more or less constant.
What is involved in punctuated equilibrium?
Long periods of time of no genetic change are interupted by rapid bursts of evolution.
What is the definition of natural selection?
It is an on going process in nature that disrupts genetic equilibrium; Evolution is a result of natural selection.
What is divergent evolution?
Divergent evolution is the process of a species evolving into two or more different species.
What happens in adaptive radiation?
A species will evolve into many different species
What is the definition of a species?
A group of similar organisms who can potentially interbreed and produce fertile offspring.
What are the barriers that help form different species?
Geographic isolation and Sympatric speciation.
What happens in geographic isolation?
The species is separated geographicly and cannot interbreed.
What happens in sympatric speciation?
A genetic barrier is formed. This is common in asexual plants where a genetic mutation means that they cannot interbreed, but because the plant is asexual, it can still produce offspring.
What is involved in natural selection?
Variation, mutations are formed, crossing over happens and sexual reproduction occurs.

Some of the variations are adaptive. This would mean that it increases an induviduals chance to survive and reproduce.

The adaptive value of the trait is determined by selective pressures that act on the phenotype such as:


Those induviduals with adaptive variations are more likely to reproduce successfully (they are more fit)
What are the five conditions in the Hardy Weinberg principle?
1. The population is very large. Chance of sampling error is thereby eliminated as an effect of genetic change.
2. Individuals show no mating preference (i.e., mating is random).
3. There is no mutation of the alleles.
4. No migration occurs, either immigration or emigration.
5. All genotypes have an equal chance of surviving and reproducing (i.e., there is no selection).
What do allele frequencies represent?
The percentage of a specific allele within a population.
How are the genotype frequencies represented?
p^2 + 2pq + q^2 = 1
What is a niche?
How an organism lives, its role within its habitat
What is competitive exclusion?
The concept that no two species can occupy the exact same niche in the same place at the same time
What was Darwin's book on natural selection?
The origin of species
What were Darwin's two main theories?
Evolution accurs, which is defined as descent with modification and that all species had descened from one or few original types of life.

His second theory said that natural selection causes evolution.
What is the name of the ancestor to all species?
A remote common ancestor
What is the name of an ancestor that is more recent than a remote common ancestor?
A recent common ancestor.
What are the three types of natural selection?
Directional selection.
Disruptive selection.
Sexual selection.
What is involved in directional selection
Induviduals with an extreme trait have more of a fitness level.
What is involved in disruptive selection?
Induviduals wit either extreme variation of a trait are more fit than those with the average trait.
What is involved in sexual selection
Those with a specific trait towards an extreme acts in attracting a mate.