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Natural Selection
Individuals with one version of a trait have greater reproductive success than do individuals with a different version.
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4 different mechinisms of evolution
mutation, genetic drift, migration, natural selection (evolution is a result of natural selection).
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Evolution
Change in allele frequencies in a population. Change due to natural pressures (peper moth).
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Population
group of organisms of the same species living in a particular area.
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Natural selection (conditions)
variation for a trait, Heritability of that trait, Differential reproductive success based on that trait(more babies). need all 3
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Fitness
measure of relative amount of reproduction of an indivitual witha particular phenotype, compared to the output with alternate phenotypes.
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Elements to an organisms fitness
- 1. measured relative to other genotypes or phenotypes in the poplation.
- 2. the enviroment
- 3. reproductive success, compared with organisms in population
- (survival of the fittest)
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Adaptation
when an organism becomes better matched to enviroment/ features that make them more fit . process of natural selection.
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Natureal selection can change the traits of a population in what 3 ways of selection.
Directional, stabilizing, disrupted
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Directionnal selection
ONE extreme from variation of population have higher fitness.
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Stabilizing selection
individuals with intermediate phenotypes are most fit
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Disruptive selection
RARE individuals with extreme phenotypes have the hightest fitness
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Mutation
Alteration of base pair sequence of an individual's DNA, alteration occurs in section of DNA that codes for a particular gene. Change in DNA may change the allele. almost always cause early death or lower reproductive success.
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Mutagens
mutation inducing chemicals
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Genetic Drift
Random change in allele frequencies that do not influance reproductive success and population expienceses evolution
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Fixation
consequence of genetic drift. occures when alleles frequency in population for a trait reches 100%. all offspring will carry that allele untill mutation occurs.
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Flounder Effect
group of indeviduals that leave the exsisting population. new population will be dominated by the genetic features present in the founding members. the new population expiences evolution.
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Bottleneck
surviving members of a catastrophic event that have different allele frequencies than the source population and, consequently, the new population will be dominated by the present features in the surviving members.
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Migration/ Gene Flow
A group of indeviduals migrates from one population to another. Both experiance change in allele frequencies as indeviduals move in and out.
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Sexual Selection
process by witch natural selection favors traits, such as ornatments or fighting behavior that gives an advantage to indaviduals of one sex in attracting matting partners.
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Artificial selection
reproductive sucess is determined by humans not nature.
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Five Lines of Evidence Demonstraiting the occurance of evolution
- -the fossil record
- -biogeography
- -comparative anatomy and embryology
- -molecular biology
- -laboratory and field experiments
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The Fossil Record
physical evidance of organism that lived in the past
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Biogeography
patterens in the geographic distribution of living organisms
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Comparative anatomy and Embryology
growth, development and body structures of major groups of organisms
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Molecular Biology
The examination of life at the level of individual molecules
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Laboratory and Field Experiments
Implementation of the scientific method to observe and study evolutionary mechanisms
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Radiometric Dating
makes it possible to determine the age of fossils. absolute and relative age
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Homologous Structures
Body structures in different organisms that, although modified over time to serve different dunctions in different species, are due to inheritance from a common evolutionary ancestor.
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Vestigial Structures
a structure on an animal that was once useful but lost its function over time due to evolution.( human appendix)
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Convergent Evolution
process of natural selection which features of an organisms not closely related come ot resemble each other as a consequence of silimar selective forces
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