New Vocabulary  Ecology: is the scientific investigation and analysis of interactions among organisms, populations, and communities and their responses to external factors in their environment  Ecosystem: all organisms that live in a place, together with their physical environment

New Vocabulary  Biosphere: consists of all life on Earth and all parts of the Earth in which life exists  Ex: land, water, and the atmosphere  Biome: is a group of ecosystems that share similar climates and typical organism

Levels of Organization in Ecology  What is the correct level of organization?  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  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?

Symbiotic Relationship  Symbiotic: relationship in which two species live close together  Types of symbiosis  Mutualism  Commensalism  Parasitism  predation

Mutualism  A symbiotic relationship in which both organisms benefit  Examples  Clownfish and sea anemone

Commensalism  A symbiotic relationship in which one organism benefits and the other neither benefits nor harmed  Examples  Shark and Pilot fish

Parasitism  A symbiotic relationship in which on organism benefits and the other is harmed  Examples  Tapeworms, liver flukes, fleas, ticks, roundworms, hookworms

Predation  A symbiotic relationship in which one organism preys on (and eats) another organism  Examples  Lion and zebra

Discussion  What kinds of relationship do humans have with other organisms?  What are some examples of these relationship?