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Evolution+Fossils+First Life Vocab

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Biology (Biological Sciences)
Heather Proctor

VOCAB: Evolution+Fossils+First Life • Artificial selection: Selection and breeding of individuals with desired traits • Darwin's Theory of Natural Selection: ◦Members in a population often vary in their inherited traits ◦All species can produce more offsprings than their environment can support, and many of these offsprings fail to survive and reproduce ◦Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals ◦The unequal ability of individuals to survive and reproduce will lead to the accumulation of favourable traits in the population over generations. • Homologous structures: Structure in different individuals that was present in their common ancestor • Vestigial structures: Remnants of features that served important functions in the organism's ancestors • Evolutionary tree: A diagram that reflects evolutionary relationships among groups of organisms • Biogeography: The geographic distribution of species, another type of evidence for evolution • Endemic: Species that are only found in a specific geographic area, eg. an island • Evolution: Change in the frequencies of alleles in a certain population over generations • Adaptations: Inherited characteristics of organisms that enhance their survival and reproduction in specific environments • Population: Localized group of individuals of the same species, expected to interbreed (A population can evolve but an individual organism cannot) ◦FACTORS AFFECTING ALLELE FREQUENCIES IN A POPULATION: 1) Mutation: Random change in an individual's DNA, hereby providing the variations that allow for evolution Can be caused by random error or structural damage to DNA due to eg. radiation Can be bad, good or neutral Huge mutations: macromutation, usually mutations to genes that affect development (in da womb) Note: mutations in gametes are likely to be passed on to offsprings (not relevant for single-cell organisms) 2) Natural selection: A process in which individuals that have certain inherited trays tend to survive and reproduce at higher rates than other individuals because of those traits--> results in adaptations (Natural selection acts on pre- existing variations, i.e. mutations) àHow it affects distribution of allele frequencies: •Directional (more of one extreme type within population, curve shift left or right) •Diversifying (Disruptive) (curve is now split between two or more regions of the type range) •Stabilizing (focusing on the most average type within population, sharper, centred curve) Sexual selection: Selection for acquisition of more or better mates Intrasexual selection: Sexual selection within one sex, e.g. for bigger antlers Intersexual selection: One of the mates is trying to be appealing to the opposite gender 3) Genetic Drift: Change in a population's gene frequencies through chance (random events) rather than selection; does not create adaptations Bottleneck: A dramatic reduction of population size (due to a natural disaster or something) that leaves only a few survivors that may lack the genetic diversity of the original population Founder effect: A small group of individuals without the genetic diversity of their original population starts a new population in a new area. 4) Gene flow: When individuals interbreed or migrate among populations=new variations. Counteracts drift (drift works through random isolation of little genetic groups, while gene flow, mixes all the separated genes again). Slows local adaptations, reduces phenotypic diversity. 5) Extinction: Process which removes some or all of a species' diversity. Extirpation: Local extinction • Neo-Darwinism (aka. "Modern Synthesis"): coined to refer to the combined understanding of natural selection+genetic basis of inheritance (1930s- 1940s). later, behaviour and structure of DNA was further understood. today, the understanding of evolution goes beyond what Darwin understood • Microevolution: Smallest scale of evolution, at the population level, done through selection or drift • Macroevolution: Evolutionary change above species level, including origin of complex novel characters, also characterized by the appearance of higher-level taxa. • Speciatio
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