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31 Cards in this Set
- Front
- Back
microevolution
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evolution at the population level
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macroevolution
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evolution at the species level and above (same forces operating but on different time scales)
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speciation
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process by which new species are formed from pre-existing ones
produces 2 general patterns: 1. anagenesis (non branching speciation) 2. cladogenesis (branching speciation) |
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Cladogenesis
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branching speciation
-increases biodiversity -responsible for diversity of life "tree of life" |
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biological species concept (BSC)
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defines species as a population or group of populations whose members have the potential to interbreed with one another in nature to produce fertile offspring
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typological species concept
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1. species defined on by appearance
2. used for asexual organisms and fossils |
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RIM--reproductive isolating mechanisms
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how reproductive isolation is maintained
--2 categories 1. pre-zygotic RIMs 2. post-zygotic RIMs |
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pre-zygotic RIMs
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operate before a hybrid zygote is formed
1. temporal isolation 2. habitat isolation 3. behavioral isolation 4. mechanical isolation 5. gametic isolation |
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temporal isolation
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species mate or flower at different times
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habitat isolation
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species mate in different habitats
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behavioral isolation
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no sexual attraction of males and females of different species
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mechanical isolation
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"lock and key" male and female sex organs of different species are anatomically incompatible
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gametic isolation
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gametes incompatible
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post-zygotic RIMs
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operate after a hybrid zygote is formed
1. hybrid inviability 2. hybrid sterility 3. hybrid breakdown |
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hybrid inviability
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hybrid dies before sexual maturity
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hybrid sterility
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hybrid lives, but is sterile and can't reproduce (mules)
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mechanisms of speciation
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1. allopatric speciation
2. sympatric speciation |
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allopatric speciaation
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speciation through geographic isolation
--prevents gene flow --genetic differences accumulate in populations due to drift, mutation, and natural selection --genetic differences prevent species from interbreeding if they come back into contact |
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sympatric speciation
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part of a population becomes a new species while in the midst of its parent population
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radiometric dating
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used to determine ages of rocks and fossils they contain
based on decay of radioactive isotopes used to establish geologic time scale |
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fossil record
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tells us when species appear and disappear
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species turnover
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changes in the fossil record
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radiations
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diversification of ancestral lineage into many specialized species
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mass extinctions
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large-scale die-offs of species
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systematics
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reconstructing the history of life on earth
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taxonomy
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naming and classifying of organisms
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father of modern taxonomy
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carolus linnaeus
1. swedish physician and botanist 2. proposed classification scheme used today |
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binomial nomenclature
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1. each species given a 2-part latinized name (a binomial)
2. first word capitalized and represents genus of species 3. second word is lowercase and represents species name 4. both words italicized or underlined |
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hierarchical classification
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grouping species into progressively broader categories
1. species 2. genus (genera) 3. family 4. order 5. class 6. phylum 7. kingdom 8. domain |
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phylogeny
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evolutionary history of a species
phylogenetic trees 1. way to visualize evolutionary relationships 3. a hypothesis of evolutionary relationships |
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homologies
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structures in different species that are similar due to common ancestry
shared evolutionary similarities |