Ecology: Organismal & Population Ecology

• Ecology is the study of the interaction of an organism with its environment
• The environment is made of biotic and abiotic components

Organismal Ecology

• It is the study of the interaction of an organism and its environment
• Behavioral ecology studies responses to stimulus, foraging and group interactions
• Evolutionary Ecology studies adaptations to the environment
• Events in ecological time influence evolutionary time processes

Population Ecology

• A population is a group of individuals of the same species living in the same area
• Population ecology focuses on factors affecting how many individuals of a species live in an area
• Population ecology is the most mathematically based subdiscipline of ecology

Populations

• A species is composed of multiple populations
• The populations experience differing environments and genetic variations, which includes selection, mutation, and drift
• Individuals can start new populations by moving to novel environments via dispersal or join different populations via gene flow
• Populations can move among different environments via mirgration

Dispersal

• Dispersal is the movement of individuals
• Dispersal can be a one-way trip
• Ecological migration is a round trip
• Dispersal is natural

Community Ecology

• A community is a group of interacting populations of different species in an area
• Community ecology deals with the whole array of interacting species in a community

Ecological interactions

• These occur between organisms and the environment
• The environment is composed of biotic and abiotic factors

Biotic Factors

• Biotic factors are organisms interacting with other species
• Interactions between organisms can be positive, negative or neutral

Interactions

• Mutualism (+/+) occurs when two species benefit from an interaction; for example, a plant and its pollinator
• Commensalism (+/0) occurs when one species benefits and the other is unaffected
• Positive/Negative interactions: Predator/Prey, Herbivore/Plant, and Parasitism, where one species receives resources with directly killing the other
• Competition (-/-) occurs where two species are competing for the same resource.
• Symbiosis which results in mutualism or one species benefiting and the other being unaffected (benefit/uneffected)

Ecosystem Ecology

• An ecosystem is the community of organisms in an area with its physical factors
• Ecosystem ecology emphasizes energy flow and chemical cycling among the various biotic and abiotic components
• This includes the movement of carbon, nitrogen and other chemicals through the ecosystem
• Climate change is an example of ecosystem ecology

Abiotic factors

• Abiotic factors are the nonliving parts of the environment
• Chemical factors include pH and salinity
• Physical factors include weather (temperature and moisture), light, and nutrients (O2 and N2)

Ecology is the study of the interaction of an organism with its environment, comprised of biotic and abiotic components. Organismal ecology studies individual interactions, while population ecology focuses on factors affecting species numbers in an area.