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AB Test 2

Terms in this set (99)

Describe how evolution occurs through the interactions among the following: the reproductive potential of a species, the normally constant size of natural populations, variation among individuals of a species, natural selection, and inheritance.
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Environmental Niche (econiche)
-the intersection of factors that defines the how, what, when where of a species' existence.
-may differ slightly depending on the ecosystem
Biotic Potential
-the maximum rate of population growth that assumes 3 ideal conditions:
1-maximum birth rate
2-minimum death rate
3-no environmental resistance
Environmental Resistance
-limits on population growth that are set both by the nonliving environment (abiotic factors-food, water, light, temp, air) as well as living environment (biotic factors- competition with other organisms, predation, disease, parasitism), either intraspecific or interspecific
Intraspecific
within the species
Interspecific
between species
The growth curve for a population before it encounters significant environmental resistance
-J-shaped curve
-name: ___
-distinguishing characteristic:
Density-independent form of environmental resistance
-form of environmental resistance
-limit population size regardless of population density
ex. natural disasters (fires, tornadoes, tidal waves, droughts, etc) and accidents (oil spills, chemical spills, global warming, collisions with meteorites, cooling trends)
Density-dependent form of environmental resistance
-form of environmental resistance
-increase in adverse effect as the population density increases
ex. predation, parasitism, disease, competition and wars.
Why is predation density dependent?
-because the more prey there are, the more predator offspring will survive.
Why is competition density-dependent?
-because competition increases with increases in population size
Why are parasitism and disease density dependent?
-because most microbes have limited mobility and spread more readily among hosts at higher population densities.
Why is competition a complex process?
-competition its usually thought as occurring between individuals, while evolution occurs at the level of a population.
-complex because we have recently found that for species that live in social groups, the competition can be between groups, not just individuals,
How does the rate of population growth change in response toboth forms of environmental resistance? How is the curve described?
-the curve begins to level off due to the pressures of environmental resistance as it reaches carrying capacity of the environment.
-curve= S-curve
Carrying Capacity
-the number of individuals of a species in a population that can live sustainably in a certain environment.
humans have caveat: subsistence technology
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