Ecology of Populations

What is Ecology? Ecological levels Organism – An individual Population – Individuals of the same species Community – Different populations in one location Ecosystem – Community of populations and their interactions with the environment (abiotic factors)

Coral Reef as an Ecosystem

Density and distribution Demographics- Density and distribution Population density – pattern of dispersal of individuals across an area of interest Resources – abiotic (nonliving) and biotic (living) components of environment Limiting factors – environmental aspects that determine where an organism lives

Population Characteristics Population Ecology: Population Characteristics Population Characteristics Population Density: The number of organisms per unit area Spatial Distribution: Dispersion: The pattern of spacing a population within an area 3 main types of dispersion Clumped Uniform Random The primary cause of dispersion is resource availability

Population Limiting Factors Population Ecology: Population Characteristics Population Limiting Factors Population growth rate How fast a given population grows Factors that influence this are: Natality (birthrate) Mortality (_____ rate) Emigration (the number of individuals moving _________ a population) Immigration (the number of individuals _________ a population) death away from moving to

Population Limiting Factors Population Ecology: Density-independent factors Population Limiting Factors Density-independent factors Factors that limit population size, regardless of population density. These are usually abiotic factors They include natural phenomena, such as weather events Drought, flooding, extreme heat or cold, tornadoes, hurricanes, fires, etc.

Population Limiting Factors Population Ecology: Density-dependent factors Population Limiting Factors Density-dependent factors Any factor in the environment that depends on the number of members in a population per unit area Usually biotic factors These include Predation Disease Parasites Competition

Community Ecology: Communities Review: A community is a group of interacting populations that occupy the same area at the same time.

Communities Limiting Factors Community Ecology: Communities Communities Limiting Factors Any abiotic or biotic factor that restricts the numbers, reproduction, or distribution of organisms.

Communities Range of Tolerance Community Ecology: Communities Communities Range of Tolerance The limits within which an organism can exist.

1. Which of the following lists include only abiotic environmental factors? a. food, temperature, fire, wind b. soil, light, predators, oxygen levels c. wind, rainfall, temperature, soil d. light, food, predators, plants   2. Which of the following descriptions about the organization of an ecosystem is correct? a. communities make up species, which make up populations b. populations make up species, which make up communities c. species make up communities, which make up populations d. species make up populations, which make up communities 3. Which of the following would represent an ecosystem? a. A food chain b. The physical features of rainforest c. A prairie d. All of these 4. Which of the following food chains correctly shows the path of matter and energy through the ecosystem? a. deer – bear – grass b. grass – deer - bear c. seeds – bear – chipmunk d. chipmunks – seed – deer