a set of spatially isolated populations linked by dispersal of individuals or gametes
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metapopulations are characterized by repeated \_______ and \_______ of the small individual populations
extinctions, colonizations
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source
the number of individuals that disperse to other populations is greater than the number of migrants they receive (place where population is doing well)
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emigration \> migration
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sink
receive more migrants than the number of individuals that disperse to other populations (where organism goes to die pretty much)
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migration \> migration
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metapopulation dynamics (high migration)
causes the metapopulation to behave as a single, large population
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metapopulation dynamics (intermediate migration)
colonization of patches left open by subpopulation extinction, mosaic of occupied and unoccupied patches
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metapopulation dynamics (no migration)
each subpopulation becomes isolated and at risk of extinction
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dp/dt \= cp(1-p) - ep
extinction and colonization of patches
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p \= proportion of habitat patches occupied at time t
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c \= patch colonization rate
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e \= patch extinction rate
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c \> e for metapopulation to persist
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isolation by distance
when patches are too far apart
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effect of patch size
small patches may be hard to find and have high extinction rates
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rescue effect
High rates of immigration that protect a population from extinction
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extinction can be caused by what two reasons for metapopulations?
1. Patchiness in habitat makes dispersal from other populations difficult
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2. Environmental conditions changing rapidly + in unpredictable manner
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T/F All populations form metapopulations
False
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What happens if e/c \> 1 what will happen in metapopulation?
metapopulation will go extinct
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Habitat Fragmentation example
Spotted owls became Northern spotted owl, Mexican spotted owl, and California spotted owl because of isolated patches
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Isolation by distance + effect of patch size example
Skipper butterflies- cows stopped grazing leading to loss of grass land leading to smaller + isolated patches making them less likely to be colonized by more butterflies to persist
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effect of patch size example (unaffected by isolation)
Shrews- live on islands in lakes, island occupancy is strongly affected by island size, but unaffected by isolation because they are such strong swimmers
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habitat fragmentation
Breakup of a habitat into smaller pieces, usually as a result of human activities, turns populations into metapopulations and into isolated populations no longer linked by dispersal
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life history characteristics
-age and size at sexual maturity
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-amount and timing of reproduction
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-survival and mortality rates
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overall pattern of life history:
growth, reproduction survival
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What do differences in life history come from?
genetic and environmental variation
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optimal life histories maximize \_________
fitness
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fitness
Ability of an organism to survive and reproduce in its environment
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metamorphosis
abrupt transition in form between larval and juvenile stages
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-different body forms, habitats, and food
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ex: caterpillar to butterfly, tadpole to frog
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phenotypic plasticity
our genotype produces different phenotypes under different environmental conditions
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phenotypic plasticity example
trees in the desert grow shorter and with smaller leaves than in cool, moist climates
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Polymorphism
The existence of more than one form of a genetic trait.
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example of morphs
tadpoles
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omnivore morph- grow slowly, metamorphose later w/ higher chance of survival, permanent ponds