population - group of single species living in a certain place
- size, density, dispersion, demographics
- population range - area throughout which a population occurs
- no population occurs in all habitats around the world
- changes as the environment changes
- dispersion - how organisms are spaced
- randomly spaced - when organisms don’t interact much
- uniformly spaced - due to competition for resources
- clumped spacing - most common form, due to strong social interaction or important resource in a certain area
- human effect - humans altering the environment changes dispersion
- metapopulations - networks of distinct populations that exchange individuals
- occurs where suitable habitats separated by unsuitable habitats
- source-sink metapopulations - organisms sent from better areas (source) to bolster worse areas (sink)
- population growth - will exceed resources if unchecked
- sex ratio - number of births directly related to number of females
- generation time - average interval between birth of individual and its offspring
- cohort - group of individuals of the same age
- survivorship - percentage of original population that survives to given age
- biotic potential - rate population will grow if no limits exist
- sigmoidal growth curve - shows limits of population growth due to carrying capacity
- density-dependent factors - based on the number of organisms
- population increases >> mortality increases or birth rates decline (negative feedback)
- Allee effect - where growth rate actually increases as population increases
- resources, disease, increased aggression, hormonal changes
- density-independent factors - natural disasters
r strategy - rapid population growth
- suited for populations far below carrying capacity
- small, short-lived growth phase
- reproduces rapidly w/ large litters
K strategy - low rate of growth
- suited for populations near carrying capacity
- takes longer to get to carrying capacity (K)
- longer generations, smaller litters
- extended parental care
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