Interactionsin

Ecosystems

Habitat

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

Lion habitat

Ecological Niche

All of the physical, chemical, and biological • 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 • 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

PredationThe process by which one species captures • The process by which one species captures and feeds upon another– Heterotrophs can prey on autotrophs and other heterotrophs

Predator – Prey Cycles

Prey • Prey outnumber predators

• Increasing numbers of prey promote increases in predator populations

Symbiosis

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

MutualismAn interspecies interaction in which both • 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 • 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

ParasitismA relationship in which one species benefits • 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