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POPULATION THE BASICS GROWTH LIMITS REGULATION POPULATION BASICS DEFINITION – members of the same species living in the same place at the same time examples: robins in Westerville, fish in Hoover Reservoir PROPERTIES – size (how many), density (number per unit area), and dispersion (arrangement: 1. even 2. random 3. clumped) GROWTH RATE – change in size of a population over time change in population size = births - deaths POPULATION GROWTH REPRODUCTIVE POTENTIAL WHAT IT IS – the maximum number of offspring that each member in a population can produce HOW TO CHANGE IT: >produce more offspring at a time >reproduce more often >reproduce earlier in life – this has the greatest effect because it shortens the generation time (the average time taken to reach reproductive age) GROWTH EXPONENTIAL GROWTH WHAT IT IS: logarithmic growth; rapid growth that increases by a multiple of the previous generation each time; represented by a J-shaped curve NECESSARY CONDITIONS Plenty of food, space, mates Little or no competition Little or no predators LIMITS CARRYING CAPACITY WHAT IT IS: the maximum number of organisms in a population that the environment can support indefinitely LIMITING RESOURCE A resource that is used at the same rate the ecosystem produces the resource OR, a natural resource that determines carrying capacity when it is limited COMPETITION DIRECT – members of a population use the same resources in the same way INDIRECT – members of a population compete for, or defend, territory or compete for social dominance LIMITS POPULATION GROWTH CURVE WITH LABELS p. 214 TIME EXPLANATION OF GROWTH CURVE POPULATION REGULATION DENSITY DEPENDENT – the size of the population and the population density matter; crowded populations are affected more than low density populations are DENSITY INDEPENDENT – the size of the population does not matter, a certain proportion of the population is affected no matter what the population density is, high or low REGULATION EXAMPLES DENSITY DEPENDENT Limited resources such as food, water, space,mates Predation Disease Parasitism DENSITY INDEPENDENT Severe weather – freeze, drought Natural disasters – flood, tornado, hurricane Human disturbance
