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Chapter 11 & 12 Voca
Chapter 11 & 12: The Evolution of Populations
| Term | Definition |
|---|---|
| Gene Pool | the combined alleles of all the individuals in a population |
| Allele Frequency | a measure of how common a certain allele is in the population |
| Normal Distribution | type of distribution in which the frequency is the highest near the mean value and decreases toward each extreme end of the range |
| Microevolution | the observable change in the allele frequencies of a population over time |
| Directional Selection | type of selection that favors phenotypes at one extreme of a trait’s range |
| Stabilizing Selection | the intermediate phenotype is favored and becomes more common in the population |
| Disruptive Selection | occurs when both extreme phenotypes are favored, while individuals with intermediate phenotypes are selected against by something in nature |
| Gene Flow | movement of alleles from one population to another |
| Genetic Drift | changes in allele frequencies that are due to chance |
| Bottleneck Effect | genetic drift that occurs after an event greatly reduces the size of a population |
| Founder Effect | genetic drift that occurs after a small number of individuals colonize a new area |
| Sexual Selection | occurs when certain traits increase reproductive success |
| Hardy-Weinberg equilibrium | very large population, no emigration or immigration, no mutations, random mating, no natural selection |
| Reproductive Isolation | occurs when members of different populations can no longer mate successfully |
| Speciation | the rise of two or more species from on existing species |
| Behavioral Isolation | isolation caused by differences in courtship or mating behaviors |
| Geographic Isolation | involves physical barriers that divide a population into two or more groups |
| Temporal Isolation | exists when timing prevents reproduction between populations |
| Convergent Evolution | evolution toward similar characteristics in unrelated species |
| Divergent Evolution | when closely related species evolve in different directions, they become increasing different |
| Coevolution | the process in which two or more species evolve in response to changes in each other |
| Extinction | the elimination of a species from Earth |
| Punctuated Equilibrium | states that episodes of speciation occur suddenly in geologic time and are follow by long periods of little evolutionary change, or stasis |
| Adaptive Radiation | process involving the diversification of one ancestral species into many descendant species |
| Relative Dating | estimates the time during which an organism lived by comparing the placement of fossils of that organism with the placement of fossils in other layers of rocks |
| Radiometric Dating | a technique that uses the natural decay rate of unstable isotopes found in materials to calculate the age of that material |
| Isotope | atoms of an element that have the same number of protons but a different number of neutrons |
| Half-life | the amount of time it takes for half of the isotope in a sample to decay into a different element, or its product isotope |
| Index Fossil | fossils of organisms that existed only during specific spans of time over large geographic areas |
| Geologic Time Scale | a representation of the history of Earth |
| Era | last tens to hundreds of millions of years and consist of two or more periods |
| Period | the most commonly used unites of time in the geologic time scale, lasting tens of millions of years |
| Epoch | the smallest units of geologic time and last several million years |
| Nebula | a cloud of gas and dust in space |
| Ribozyme | RNA molecules that can catalyze specific chemical reactions |
| Cyanobacteria | bacteria that can carry out photosynthesis |
| Endosymbiosis | a relationship in which one organism lives within the body of another with both organisms benefitting |
| Paleozoic | where multicellular organisms first appeared 542 million years ago |
| Cambrian Explosion | earliest part of the Paleozoic where a huge diversity of animal species evolved |
| Mesozoic | began 251 million years ago and ended 65 million years ago |
| Cenozoic | began 65 million years ago and continues today |
| Primate | make up a category of mammals with flexible hands and feed, forward looking eyes, and enlarged brains relative to body size |
| Prosimian | the oldest living primate group, and most are small and active at night |
| Anthropoid | the humanlike primates, are first subdivided into New World monkeys, Old World monkeys, and hominoids |
| Hominid | includes orangutans, chimpanzees, gorillas, and humans, but not gibbons |
| Bipedal | animals that can walk on two legs |
Created by:
SavanahT
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