Ecosystem Interactions Lesson 7 September 1st, 2010

Biotic Interactions Organisms in a community interact with one another in many ways. Three main ways are through symbiosis, predation, and competition.

Symbiotic Relationships (3 types) Symbiosis is a close interaction between two different species in which members of one species live in, on, or near members of another species. 1. Commensalism + / 0 relationship One partner benefits without significantly affecting the other Example – Clown fish and anemone

Symbiotic Relationships (3 types)

Symbiotic Relationships (3 types) 2. Mutualism + / + relationship Both organisms benefit Example – Bees and flowers, crocodiles and dikkop birds

Symbiotic Relationships (3 types)

Symbiotic Relationships (3 types) 3. Parasitism +/ - relationship One organism, the parasite, harms the host Example – Lamprey, tick

Symbiotic Relationships (3 types)

Predator – Prey Relationships When one organism consumes a second organism Example – Lions and Zebras Some species use mimicry to avoid predators one species looks like another species. Monarch butterfly Viceroy Butterfly

Predator – Prey Relationships

Competitive Relationships (2 types) Where organisms compete for an important resource such as food, shelter or possibly mates. May have negative effects on one another. Actual fighting or exploitative competition 1. Intraspecific Between members of the same species Individuals may compete over food, water, light, space, safe sites, or mates. Important factor limiting the population size of many species.

Competitive Relationships (2 types) 1. Intraspecific

Competitive Relationships (2 types) 2. Interspecific Between 2 or more species As the population of one species increases, it may limit the density of the competing species

Competitive Relationships (2 types) 2. Interspecific

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