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Chapter 23 Mech of E
Mechanisms of evolution
| Question | Answer |
|---|---|
| Evolution | Change in a population over time |
| What level does evolution occur at? | Population, because and individual cannot pass genes along by themselves. |
| Population | localized group capable of breeding and producing fertile offspring |
| What is the smallest unit of evolution? | population |
| Microevolution | evolution of a population from one generation to the next. |
| Genetic Variation | Differences among individuls in their DNA |
| How is genetic vatiation measured? | By average heterozygosisty (Aa) |
| What are the sources of genetic variation? | Mutations, gene duplication (smell), rapid reproduction (short life span organisms), Sexual Reproduction |
| Discrete Traits | 'either this or that' (having hitchikers thumb or not having it) |
| Quantitative Characteristics | determined by multiple genes (fur color is determined by 3 diff genes, pigment is determined by 7 different ones) |
| Gene pool | all alleles in every locus in all members |
| Geographic Variation | occurs between populations |
| Macroevolution | Broader aspects of evolution, bigger evolution over larger periods of time. |
| Conditions for Hardy-Weinberg? | 1.no mutations 2. no natural selection 3. no drift 4.no gene flow 5. must be random mating |
| Natural selection | must be heritable, acts on an individual but evolves whole population. |
| Relative Fitness | number of successful offspring provided to next generation |
| Directional selection | favors one extreme (giraffe with longer necks) |
| Disruptive selection | favors 2 extremes (birds with long and small beaks, no middle size) |
| Stabilizing Selection | favors new extremes, this is most often seen. REDUCES VARIATION (baby birth weight) |
| What happened in 1831? | Charles Darwin set sail on Beagle to South America for 5 years. |
| Reason for Darwin traveling to South America? | Hired by the military to chart the coastline. |
| What did Darwin do in South America? | Collected plants/animal specimens. Detailed notes of climate & weather. Watched birds. |
| Artificial Selection | breeding for desired traits |
| Sexual Selection | individuals with certain traiits are more likely to obtain a mate than others. (Cardinals) |
| Genetic Drift | radom events that cause the fluctuation of allele frequencies. Significant impact on small populations. |
| What are the two types of drift? | Founder effect and Bottleneck effect. |
| Founder effect | individuals isolated from a population. Happens generally with islands |
| Bottle neck effect | significant drop in population size due to a random event. |
| Gene flow | migration of individuals in and out of a population. HAVE TO CONTRIBUTE TO GENETIC VARIATION!! (snowbirds) |
| Why cant natural selection produce a perfect organism? | 1.can only act on existing variation 2. evolution is limited by historical constraints 3.adaptations are comprimises 4. randomness, selection, environmental interact. |
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dpwafle0122
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