Interactionsin

Ecosystems

Habitat

• All of the biotic and abiotic factors in the area where an organism lives

Lion habitat

Ecological Niche

• All of the physical, chemical, and biological factors that a species needs to survive, stay healthy, and reproduce– Food – Abiotic conditions – Behavior

Competitive Exclusion

• When two species are competing for the same resources, one species will be better suited to the niche, and the other species will be pushed into another niche or become extinct

• Invasive species may outcompete organisms that are native to a particular region

Predation• The process by which one species

captures and feeds upon another– Heterotrophs can prey on autotrophs

and other heterotrophs

Predator – Prey Cycles

• Prey outnumber predators

• Increasing numbers of prey promote increases in predator populations

Symbiosis

• A close ecological relationship between two or more organisms of different species that live in direct contact with one another–Mutualism–Commensalism–Parasitism

Mutualism• An interspecies interaction in which

both species benefit– Flowers and pollinating insects– Humans and intestinal E. coli– Clown fish and anemones

Commensalism

• A relationship between two organisms in which one receives an ecological benefit from another, while the other neither benefits or is harmed

• Many ecologists believe that commensalism is rare, and that most such relationships are probably subtle mutualism or parasitism

Parasitism• A relationship in which one species

benefits while the other is harmed.• Many parasites have complex

lifecycles involving more than one host

Seen “Alien” ?

The Parasitic Life Cycle of the Tse-Tse Fly

Tapeworm lifecycle