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Population Ecology
Population and how they interact with their environment
| Term | Definition |
|---|---|
| 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
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