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Evolution affects _____________, not _______________.
Populations, individuals
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The idea behind the Hardy-Weinberg Law is.....
Phenotypes and genotypes tend to come into equilibrium in populations if destabilizing factors are not operative.
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Hardy-Weinberg equilibrium is bases on assumptions that almost are never met. What are they?
- 1]random mating-each individual has an equal chance of mating with any other-sexed individual
- 2]no random genetic drift; larger population so no chance events
- 3]no gene flow; immigrants bringing in or emigrants taking away rare alleles
- 4]no mutation; which would add new alleles
- 5]no natural selection; no alleles favored or selected against
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Life history characteristics are based on ____________________________.
environmental constraints
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In stable habitats, the environment is predictable so populations will be __________ K.
near
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In __________ habitats, the environment is predictable so populations will be near K.
stable
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Define K-selecting.. and explain where a K-selecting organism would be found.
Low reproductive rate, Found in stable habitats where the environment is predicable.
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In ____________ habitats, K may be moving at different times so it is difficult to track K.
unstable
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Define r-selecting.. and explain where a r-selecting organism would be found.
High reproductive rate, Found in environments that tend to select organisms that can respond quickly to change, so biotic potential (r) is more closely approximated (r-selecting)
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What does 'r' mean in r-selecting?
biotic potential
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Describe some traits in r-selected organisms..
- early maturity (>r)
- numerous young
- small young (to be numerous)
- short life (react to change quickly)
- iteroparous (animal:several breeding iterations per season)
- annual (if plant)
- less parental care (too many young)
- Less competitibe ability (habitat may be empty)
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Define iteroparous.. What type of organisms would this adjective describe?
It means several breeding iterations per season. Found in r-selected organisms.
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Why do r-selected organisms have small young?
They produce a lot of offspring at one time. They aren't able to stay within the mother for an extensive period of time. They produce them small so they can be numerous.
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Describe some traits in K-selected organisms..
- later maturity (few young
- larger young (> survival by investment)
- long life (slow growth and maturity)
- semelparous (animal breeding once per season)
- perennial (stable environment)
- more parental care (teach survival skills)
- more competitibe ability (population near K, so may be crowded)
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Define semelparous.. What type of organisms would this adjective describe?
It means breeding only once per season. Found in K-selected organisms.
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Why do K-selected organisms have larger young?
They invest a lot into a few offspring. They carry them longer so that they might have a advantage once born. The longer gestation period allows them to grow larger.
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r vs K selected. Which has more parental care? Why?
K-selected. They have more invested into their young.
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Definition of species into r and K-selected is relative. How so?
A coyote could be (K) relative to a grasshopper mouse (r). However, a grasshopper mouse could be (K) relative to a vole (r)
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Define plasticity.. What does that have to do with the categorization of life history traits?
Flexibility to alter trait. Life history traits cannot be cleanly categorized by human models. Some species are able to alter their traits in order to adapt to change (e.g., population density).
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In regards to endangered species, an organism with a ________________ life history strategy would require closer monitoring. Why?
K-selected. Reproductive potential (r) is low. Example; California Condors.
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In regards to hunting interests, an organism with a _______________ life history strategy would be ideal in order to sustain populations for hunters. Why?
r-selected. The high biotic potential of an r-selected organism would be able to quickly repopulate.
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Define sociobiology...
Study of the biological basis of social behavior.
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Define altruism...
helping others at a cost to one's self.
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Explain altruism in genetic terms..
Behavior that raises the fitness of another individual while lowering one's own fitness.
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Define selfishness.. What is it the opposite of?
Is behavior that benefits the individual at a cost to others. Opposite = altruism
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What is kin selection?
genes are the units of natural selection???<---not sure.
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Describe what is meant by the phrase "selfish gene"..
A gene wants to leave as many copies of itself as possible. It doesn't care about actually having offspring as long as lots of relative are produced.
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In regards to kin selection, describe how helping relatives can be thought of as selfish..
I am genetically similar to my relatives. They carry the same genes as me. By helping them, I am helping my genes. The "selfish gene" theory.
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________________ is the primary explanation for eusociality in evolution of castes of social hymenoptera.
Kin selection
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