Niches and Community Interactions Unit 5 Section 2

Why do organisms live where they do? Each species has a range of conditions under which it can grow and reproduce These conditions help define where and how an organism lives

Habitat and Niche Habitat – place where an organism lives Example: Habitat of a bullfrog is a pond Think of it like an organism’s address Niche – Occupation of an organism Includes: how it gets its food, reproduces, avoids predators, etc. Niche determines its habitat Example: woodpeckers can’t live in grasslands because their niche is to find insects in tree trunks!!

Competition Organisms often try to use a limited resource in the same place at the same time as other organisms This is called Competition Can occur between the same species or different species Compete for things like: food, space and mates Competition results in natural selection. Only those with the best traits for that environment will survive and reproduce No two species can have the same niche in the same environment at the same time this is called the competitive exclusion principle

Predator-Prey Relationships Predation: Members of one population are the food source for members of another population Predator – organism doing the eating Prey – organism that is being eaten Predator keeps the prey population from getting too big

Herbivore-Plant Relationships Herbivory – when herbivore feeds on a producer Keeps the plant population from getting too large

Keystone Species A population change in one species can cause dramatic changes in a community This is called a keystone species

Symbioses Symbiosis – any relationship in which two species live closely together Three main types of symbiotic relationships Mutualism Parasitism Commensalism

Mutualism Mutualism – both organisms benefit Clownfish is immune to sea anemone stings and gets protected from predators Sea anemone gets protection from clownfish who chases away bigger fish that try to eat it

Parasitism Parasite – lives on or in another organism that it uses for food and sometimes for shelter Host – organism the parasite uses One organism is helped while the other is harmed Host organism continues to live and is not killed right away just harmed Examples: tapeworms, flukes, ticks

Commensalism One organism benefits and the other is neither helped nor harmed Barnacles attach themselves to whales and benefit from constant movement of water and food particles past the swimming whale Whale is neither harmed nor helped by the barnacle