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Mechanisms of Evolution

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created 1 year ago by hyork
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9th grade, 10th grade

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1

adaptation

a change or the process of change by which an organism or species becomes better suited to its environment.

2

Charles Darwin

English natural scientist who formulated a theory of evolution by naturalselection (1809-1882)

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Genetic Variation

Genetic diversity in a population or species as a result of new gene combinations (e.g. crossing over of chromosomes), genetic mutations, genetic drift, etc.

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limiting factor

an environmental factor that tends to limit population size.

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Natural Selection

the process by which forms of life having traits that better enable them to adapt to specific environmental pressures, as predators, changes in climate, or competition for food or mates, will tend to survive and reproduce in greater numbers than others of their kind, thus ensuring the perpetuation of those favorable traits in succeeding generations.

6

Overpopulation

The population of an environment by a particular species in excess of the environment's carrying capacity. The effects of overpopulation can include the depletion of resources, environmental deterioration, and the prevalence of famine and disease.

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Population

all the individuals of one species in a given area.

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Reproductive Success

a heritable feature that increases offspring will be selected for over time in a population because individuals with higher success will contribute more offspring to future generations and this, in turn, causes the frequency of the offspring produced-enhancing allele (gene variant) to become more common over generational time in that population.

9

Fitness

a property of an allele that refers to its relative likelihood of representation in future generations in a population. An allele will be more likely to be represented in future generations within a population that is better suited than an allele for the same gene that's less suited. .

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gene frequency

the ratio of a particular allele to the total of all other alleles of the same gene in a given population.

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gene pool

the stock of different genes in an interbreeding population.

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Non- Random Mating (Artificial Selection)

The breeding of plants and animals to produce desirable traits. Organisms with the desired traits, such as size or taste, are artificially mated or cross-pollinated with organisms with similar desired traits.

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Camouflage

an adaptation that allows animals to blend in with certain aspects of their environment.

14

mimcry

a similarity of one organism, usually an animal, to another that has evolved because the resemblance is selectively favoured by the behaviour of a shared signal receiver that can respond to both.

15

Hardy-Weinberg Principle

allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.

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Stabilizing selection

Instead of favoring individuals with extreme phenotypes, it favors the intermediate variants.

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directional selection

an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype

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disruptive selection

changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups.

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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.

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emigration

Pertaining to animals that are moving away from their natural environment into another geographical niche.

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immigration

The movement of organisms to a specific area, perhaps, for example, an upstream aquatic environment to further downstream.

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gene flow

the transfer of alleles or genes from one population to another. Migration into or out of a population may be responsible for a marked change in allele frequencies

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mutations

A change in a DNA sequence resulting in traits that are either desired, undesired, or neutral.