Community Interactions

KEY CONCEPT Every organism has a habitat and a niche.

A habitat differs from a niche. A habitat is all aspects of the area in which an organism lives. biotic factors abiotic factors An ecological niche includes all of the factors that a species needs to survive, stay healthy, and reproduce. A “role” in their community food abiotic conditions behavior

Ecological equivalents are species that occupy similar niches but live in different geographical regions. Madagascar South America

when organisms live together in an ecological community they interact constantly. Three types of interactions Competition Predation Symbiosis

Competition- competing for resources occurs due to a limited number of resources Intraspecific competition Interspecific competition Resource- any necessity of life. water, nutrients, light, food. Competitive exclusion principle- no two species can occupy the same niche in the same habitat at the same time

Competitive exclusion has different outcomes. One species is better suited to the niche and the other will either be pushed out or become extinct. The niche will be divided. The two species will further diverge.

Predation Predation- when an organism captures and feeds on another organism. Predator- hunter Prey- hunted

Symbiosis Symbiosis- any relationship where two species live closely together. (3 types) Mutualism Commensalism Parasitism

Symbiosis Mutualism- both species benefit from a relationship. Lichens (fungus and Algae) One example is the lichens, little non-descript patches of stuff you see growing on rocks and tree bark. This is a symbiosis, consisting of a fungus and an alga. The fungus provides a protective home for the algae, and gathers mineral nutrients from rainwater and from dissolving the rock underneath. The alga gathers energy from the sun. There are thousands of species of lichen in the world; actually thousands of species of fungi with just a few species of algae which can form a partnership with almost any of them.

Symbiosis Commensalism – One member of a symbiotic relationship benefits and the other is neither helped or harmed Ex. Holes used by bluebirds in a tree were chiseled out by woodpeckers after it has been abandoned

+ Ø Human Our eyelashes are home to tiny mites that feast on oil secretions and dead skin. Without harming us, up to 20 mites may be living in one eyelash follicle. Demodicids Eyelash mites find all they need to survive in the tiny follicles of eyelashes. Magnified here 225 times, these creatures measure 0.4 mm in length and can be seen only with a microscope. + Organism benefits Ø Organism is not affected Commensalism

Symbiosis Parasitism- One creature benefits and one creature is harmed Ex tapeworm. Feeds in a humans intestines absorbing his/her nutrients.

_ + Organism benefits Organism is affected Hornworm caterpillar The host hornworm will eventually die as its organs are consumed by wasp larvae. Braconid wasp Braconid larvae feed on their host and release themselves shortly before reaching the pupae stage of development. Parasitism

Relationships: Symbiosis = Living Together a) commensalism b) mutualism c) parasitism

Identify these relationships