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Population Ecology

Population and how they interact with their environment

Population All the individuals of a species that live together in an area
Demography The statistical study of populations, allows predictions to be made about how a population will change
Three Key Features of Populations 1. Size 2. Density 3. Dispersion
Size Number of individuals in an area
Growth Rate (birth rate + Immigration) - (death rate + emigration) =Rate of population growth How many individuals are born and move into an area vs how many die and move out of the area
Density measure of population per unit area or unit volume
Population Density # of individuals / unit of space
Immigration movement of individuals into a population
Emigration movement of individuals out of a population
Density- dependent factors Biotic factors in the environment that have an increasing effect as population size increases (disease, competition, parasites)
Density- independent factors Aboiotic factors in the environment that affect populations regardless of their density (temperature, weather) A cold snowy winter can decrease birth rates and increase death rates in the spring for deer
Dispersion: spacing of organisms Clumped (aggregated), Uniform, Random
Population density Number of individuals in a given area or volume; count all individuals in a population, estimate by sampling, mark-recapture method
Idealizing models describe two kinds of population growth 1. Exponential Growth 2. Logistic Growth
Exponential Growth A pattern of slow then rapid growth of a population. Growth curve resembles a J.
Logistic Growth A pattern of slow then rapid growth finish in a stable population at carrying capacity growth curve resembles an S.
Carrying Capacity (K) -The maximum population size that can be supported by the available resources. -There can only be as many organisms as the environmental resources can support
Declining birth rate or increasing death rate are caused by -Limited food supply -The buildup toxic wastes -Increased disease -Predation
R Strategists -Short life span -Small body size -Reproduce quickly -Have many young -Little parental care
K Strategists -Longest life span -Large body size -Reproduce slowly -Have few young -Provides parental care
Age Distribution -Distribution of males and females in each age group of population -Used to predict future population growth
Species diversity The more species and number of that species that occupy a habitat the more diverse the community is
Ecological diversity The more diverse an ecosystem is the more stable it is and the more it has to offer in resources
Genetic diversity The more diverse the genetics of a species the less likely it is to collapse in the face of hardship
Habitat loss -The single most common cause of species extinction -Reduces biodiversity
Reasons for habitat loss -Farming -Logging -Urbanization
Ecological service -Bees pollinate flowers -Roots hold soil -Predators prevent overgrazing
Economic benefit -Honey, fruit and other crops are valuable and depend on diversity of pollinators -Plants can be used for medical needs
Human population growth - J curves growth -Rate: 1.3% yearly -Growing rate is 80 million yearly
Mutualism Both species benefit
Parasitism One organisms benefits at the expense of another
Commensalism One species benefits while the other is not affected
Climax community A community goes through succession, then when it is stable at the very end it is the climax
Climate change The recent rise in earths surface temperatures
Created by: kieren1