COMMUNITY RELATIONSHIPS In Nature, many different populations interact in a community. If we look at the interactions of any two populations we will find that they interact in a limited number of ways.

COMMUNITY RELATIONSHIPS Organisms relate to each other in only 5 types of relationships: Mutualism Commensalism Parasitism Predation Competition

COMMUNITY RELATIONSHIPS Organisms relate to each other in only 5 types of relationships: Mutualism Commensalism Parasitism Predation Competition

COMMUNITY RELATIONSHIPS Organisms relate to each other in only 5 types of relationships: Mutualism: a relationship where both populations benefit. Lichens: a combination of an algae and fungus: the algae provides food for itself and the fungus, the fungus provides protection for the algae. Termites have a protozoa in their intestines that digests cellulose. The protozoa gets a food supply, the termite gets digested food.

COMMUNITY RELATIONSHIPS Organisms relate to each other in only 5 types of relationships: Mutualism Commensalism Parasitism Predation Competition : a relationship where one organism is benefited and the other is not affected. Birds that nest in trees benefit by having the nest somewhat protected. The tree is neither helped nor harmed. Some birds follow large herbivores around and eat insects disturbed by the movement of the herbivore. The birds get food, the herbivore is unaffected.

COMMUNITY RELATIONSHIPS Organisms relate to each other in only 5 types of relationships: Mutualism Commensalism Parasitism Predation Competition : a relationship where one organism is benefited and the other is harmed. The organism that is benefited is the parasite and the organism that is harmed is the host. The parasite harms the host, but rarely kills it. Why? Fleas and dogs/cats: flea is the parasite, dog/cat is host Ticks, intestinal parasites, etc are well-known.

COMMUNITY RELATIONSHIPS Organisms relate to each other in only 5 types of relationships: Mutualism Commensalism Parasitism Predation Competition Symbiosis is the term used for these 3 relationships where at least one of the organisms receives a benefit and the relationship is a long-lasting one. Mutualism, commensalism, and parasitism are symbiotic relationships

COMMUNITY RELATIONSHIPS Organisms relate to each other in only 5 types of relationships: Mutualism Commensalism Parasitism Predation Competition : a relationship where one organism benefits and the other dies. The organism that benefits is the predator and the organism that dies is the prey. Some consider this relationship to be a form of parasitism. Why? Why not? There are many common examples of predator-prey relationships.

COMMUNITY RELATIONSHIPS Organisms relate to each other in only 5 types of relationships: Mutualism Commensalism Parasitism Predation Competition : a relationship where both organisms are harmed. Both organisms are competing for a limited resource in their ecosystem. The harm is that there are fewer of one organism because the other organism is taking some of the contested resource. For example: a pasture can support 10 cows or 10 horses. If both cows and horses are on this pasture, it will support less than 10 of either. Food, shelter, water … any density dependent factor

COMMUNITY RELATIONSHIPS To summarize: Relationships Organism A Organism B Mutualism + Commensalism Parasitism -- Predation -- (dead) Competition

RHYTHMS Many events in Nature repeat at regular intervals Circadian rhythms: repeat on a daily basis Diurnal: active in the daytime Nocturnal: active during the nighttime Annual rhythms: repeat on a yearly basis Special annual rhythms: Hibernation: slow down in winter Estivation: slow down in summer

Biogeochemical Cycles Bio = “living”, geo = “earth”, so biogeochemical means cycling of nutrients (chemicals) between living (bio) and non-living (geo) states. Water cycle (page 413) Carbon cycle (page 414) Nitrogen cycle (page 415)

Habitat and Niche Habitat: where an organism lives. Niche: what an organism does in its habitat. The horses slowly graze the green pasture.

Habitat and Niche Habitat: where an organism lives. Niche: what an organism does in its habitat. The horses slowly graze the green pasture. The beavers cut down trees on the creek bank and build a dam in the stream.

Habitat and Niche Habitat: where an organism lives. Niche: what an organism does in its habitat. The horses slowly graze the green pasture. The beavers cut down trees on the creek bank and build a dam in the stream.

HAVE A GREAT DAY!!