a biological community is a collection of populations of different species living close enough to...
TRANSCRIPT
• 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 InteractionsCommunity 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” 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
Keystone SpeciesKeystone 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 rolein 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 livesHabitat: a place where an organism lives
• Habitats include both biotic and abiotic factors like shelter, water, food and space.
• Examples:forestdesertpondtidal poollarge intestineneighborhood street
Niche: an individual’s ecological roleNiche: 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.