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Transcript
Ecology - the study of the relationships between organisms and their environment. The environment includes an organism’s its surroundings and other organisms. Ecology studies the relationships and interactions among individuals within a population and with individuals of different populations. Because all organisms have become adapted to their surroundings and are always adapting to a changing environment, natural selection and evolution are also a part of ecology Population - a population consists of the individuals of a given species that occur together at one place at one time. The population is the major functional unit of the ecosystem and it plays a particular role in energy flow and cycling of nutrients Ecosystem - an ecosystem is the sum of all of the biological and nonbiological parts of an area that interact to cause plants to grow and decay, soils or sediments to form, and the chemistry of water to change rmax = maximum intrinsic rate of natural increase for a population Biotic potential - the innate capacity of a population to increase in number under ideal conditions = rmaxN r = the actual rate of population increase = dN/Ndt = (b - d)/N Environmental resistance - a natural check on the growth of wild populations; includes factors such as disease, accumulation of waste products, lack of food, lack of space, light, or water Carrying capacity = K = the number of individuals in a population that can be supported at a given place over a long period of time logistic growth equation = dN/dt = rmax N((K - N)/K) SOME CHARACTERISTICS OF r AND K STRATEGISTS r strategists K strategists Climate variable and/or unpredictable fairly constant and/or predictable Mortality density independent density dependent Survivorship high mortality when young; high survivorship afterwards either little morality until a certain age, or constant death rates over a period of time Intraspecific and interspecific competition variable, lax usually keen Parental care minimal intensive Adaptations rapid development; high rate of population increase; early reproduction; small body size; single reproduction (big bang = semelparity) slower development; greater competitive ability; delayed reproduction; larger body size; repeated reproductions (iteroparity) Length of life Usually less than one year Usually more that one year