Levels of Organization in Ecology  What is the correct level of organization (Think back to the card activity from our previous class.)?  atom  molecule  organelle  cell  tissue  organ  organ system  organism  population  community  ecosystem

Populations vs. Communities  What is the difference between a biological population and a biological community?  A biological population is “a group of organisms of one species that interbreed and live in the same place at the same time,” while a biological community is “a group of interdependent organisms living and interacting with each other in the same habitat.”

Limiting Factors  Do populations often grow exponentially?  What are limiting factors?  Limiting factors are any factors (things) that affect an organism’s ability to survive in its environment. These factors affect population growth.  Examples?  Availability of food and water, predators, temperature, space/shelter, and disease

Density-Dependent Factors  What are density-dependent factors?  Factors that depend upon the size of the population. These factors will have an increasing effect as the population size increases.  Examples?  Availability of food and water, competition, predators, and disease

Competition  What is competition?  Competition is “a symbiotic relationship between or among living things for resources, such as food, space, shelter, mate, ecological status, etc.”.  Examples?  Trees that grow very close together vie for sunlight and soil nutrients, lions and tigers that vie for similar prey, and a farm of rice paddies with weeds growing in the field

Competition  What happens to competition between individuals as population size increases?  Competition will also increase.  If the demand for resources exceeds the supply, then the population size will eventually decrease.

Density-Independent Factors  What are density-independent factors?  Factors that are not dependent upon the size of the population and can affect any population.  Examples?  Temperature, weather (storms, floods, drought), and habitat disruption by humans

Carrying Capacity

 Carrying capacity is the “largest number of individuals of a particular species that can survive over long periods of time in a given environment.”  Why is knowing carrying capacity important to ecologists?