A biological community is a collection of populations of different species living close enough to interact with one another For example, a pond = insects, fish, algae, animals, plants, frogs all live close enough to interact Three types of community interactions: – Competition – Predation – Symbiosis mutualismcommensalismparasitism Community Interactions

Competition for resources like, water, nutrients, light, food, territory Occurs due to a limited number of resources No two species can occupy the same niche in the same habitat at the same time competing for the same resources Competition Competition for Food Competition for Space Competition for sunlight

Predation Predation is when an organism captures and feeds on another organism. Predator = “the hunter”Prey = “the hunted” Predator = “the hunter” and Prey = “the hunted” Lynx hunting the snowshoe hare Bigger fish eating smaller fish Beetle eating an earthworm

Symbiosis Symbiosis- any relationship where two species live closely together. Three types: – Mutualism (+/+) both organisms benefit – Commensalism (+/ Ø ) one benefits, other unaffected – Parasitism (+/-) one benefits, other harmed

Mutualism (+/+) Mutualism: both species benefit from a relationship. Cleaner birds and crocodiles: Birds eat decaying meat stuck between crocodile teeth Clown fish and anemones: Clown fish chases away fish that like to eat anemones while the clown fish are protected from predator fish by the stinging tentacles of the anemone Lichens (fungus/algae): the fungi provides structure and protection for the algae and also obtains water and mineral; algae makes food for the fungi through photosynthesis

Symbiotic Commensalism (+/ø) Commensalism – One member of a symbiotic relationship benefits and the other is neither helped nor harmed Triggerfish creates feeding opportunities for smaller fish by moving large rocks too big for them to shift themselves. As the whales travel, the barnacles gain access to nutrient-rich waters, while the whale neither benefits nor is harmed by its riders Bugs (non parasitic) living on large herbivores like water buffalo. Birds cleaning non- parasitic bugs off of the water buffalo

Symbiotic Parasitism (+/-) Parasitism- a relationship where one organism (parasite) depends on another (host) for nourishment or other benefit. Some species live within the host Ticks are parasites that feed on the blood of their hosts often carrying diseases Tapeworm eggs are usually eaten in contaminated meat and then mature in the animal’s intestines

CUCKOO BIRD WARBLER BIRD

Keystone Species A keystone species is a species that plays a critical role in maintaining the structure of an ecological community Removing the keystone species, the food web can be adversely affected “Holds the community together” Plays an important role in stabilizing population sizes in the community

Keystone Species Removing the Pisaster starfish caused a loss of diversity in the intertidal zone of the Pacific Northwest. Being a top predator, Pisaster kept lesser organisms in the food chain within stable limits. When removed, these populations flourished and crowded out other species. Within ten years, seven species disappeared from the community = biodiversity loss. Pacific Northwest Intertidal Zone

Habitat: a place where an organism lives Habitats include both biotic and abiotic factors like shelter, water, food and space. Examples: forest desert pond tidal pool large intestine neighborhood street

Niche: an individual’s ecological role A niche describes the way of life of a species. Each species is thought to have a separate, unique niche in a habitat A niche includes its place in a food web – Are they a food source for others? Top carnivore? A niche includes how the organism lives, eats, reproduces How they uses environ- mental conditions, like sunlight, temperature, and food.

HABITAT vs NICHE FLOWERS FRUIT HOLES

EXIT TICKET 1)What is a community? 2)Name the 3 types of community interactions. 3) Name the 3 types of symbiosis. 4) How do mutualism, commensalism, and parasitism differ? 5) What is a Keystone species?