HOW ORGANISMS INTERACT IN COMMUNITIES WHAT SHAPES A COMMUNITY?? PREDATION & COMPETITION!! (food, SHELTER, light, nutrients, water)

Five Basic Interactions Between Species 1)Competition 1)Interspecific competition – between two or more species 2)Intraspecific competition – between members of same species 2)Predation 3)Parasitism 4)Mutualism 5)Commensalism

WHAT IS A NICHE? An organism’s niche describes: 1.The organism’s role in the community 2.It’s use of resources

 Fundamental Niche  the full range of conditions and resources it could potentially use  Determined by abiotic factors  Realized Niche  that part of a fundamental niche that an organism occupies  Determined by biotic factors (COMPETITION!)

INTERSPECIFIC COMPETITION = niches of two different species overlaps  Migrate  Shifts its feeding habits  One of the species suffers population decline (even to extinction)

If the niches of two species overlap completely or significantly – how long can they both last? What’s an organism to do? Move, adapt, or die Avoid or weaken competition by: Symbiosis Resource partitioning

A niche restricted by competition is a a)Fundamental niche b)Realized niche c)Resource partitioned niche True or False: A fundamental niche includes the full resources and habitat an organism can survive in.

 Have broad ranges  Live in a variety of places, eat a spectrum of foods, & tolerate a wide range of environmental conditions  Have narrow ranges  Live in one type of habitat, rely on one type of food source, or have limited range of environmental tolerance  Are typically endangered species

A: Interspecific CompetitionB: Intraspecific Competition 1. Two squirrels race up a tree to reach a hidden pile of nuts. 2. A hyena chases off a vulture to feast on an antelope carcass. 3. Different species of shrubs and grasses on the forest floor compete for sunlight. 4. Brown bears hunting for fish on a river’s edge fight over space. 5. Male big horn sheep butt heads violently in competition for mates.