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18 Cards in this Set
- Front
- Back
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Species: |
a population of individuals that can breed and produceviable offspring . This is Biological Species Concept |
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Morphological Species Concept |
classification based on phenotype |
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Ecological Species |
Concept-based on living in same habitat |
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Phylogenetic spcies |
based on taxonomy |
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Reproductive barriers -Divided into two groups: |
1. Prezygotic barriers 2. Postzygotic |
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Prezygotic barriers |
A. Temporal isolation B. Habitat isolation C. Behavioral isolation |
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Postzygotic |
A. Hybrid inviability (hybrids do not survive to maturity)B. Hybrid sterility (hybrids survive but are sterile) |
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How do species start? |
Most often a geographic barrier prevents gene flow Mutation and genetic drift occur Called allopatric speciation |
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Allopatric speciation |
Several geologic processes can isolate populations. A mountain range may emerge and gradually split a population oforganisms A large lake may shrink until there are several smaller lakes Continents themselves can split and move apart. |
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How large must a geographic barrier be to keep allopatricpopulations apart? |
Answer depends on the ability of the organisms to move. Birds, mountain lions, and coyotes can easily cross mountain ranges. |
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How do reproductive barriers arise? |
The environment of an isolated population may include: different food sources different types of pollinators different predators Result of natural selection acting on preexisting |
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Other ways for species to arise |
New species can arise right next to parent population Known as Sympatric speciation Reproductive isolation keeps parental and new species apart |
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of all living plant species are descendants of ancestors that formed bypolyploid speciation. |
80% |
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Polyploid plants |
• cotton• oats• potatoes• bananas• peanuts• barley• plums• apples•sugarcane• coffee• wheat |
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Even more ways for new species to arise.. |
If an individual is introduced into a new environment Must adapt to changes If leads to new species is called adaptive radiation Common when individuals reach an island |
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What happens when separated populations of closely relatedspecies come back into contact with each other? |
Biologists try to answer such questions by studying hybrid zones |
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How does evolution “move along”? -Two major theories: |
1. Gradualism Model 2. Punctuate evolution |
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Gradualism Model |
species gradually change over time, evolutionruns at constant slow rate |
