Community InteractionsClimate

NicheCompetition

Predation and herbivorySymbiotic relationships

WeatherDay-to-day

conditions are weather

ClimateClimate is year-after-year weather patterns

The greenhouse effect

Climate ZonesUnequal distribution of the sun’s heat

Tropical: 23.5· north to 23.5 southDirect sunlight

Temperate:23.5- 66.5 north and southVariable and seasonal

Polar:66.5-90 north and southVariable and seasonal

Where do winds come from?

NicheA niche is habitat plus ‘occupation’

What is your niche?Tolerances (sunlight, temp)Resources (water, food, space, light)Physical aspects (abiotic factors)Biotic factors for survival (type of food, how

you get it)

Competition shapes communitiesPlant roots compete for water

Animals compete for food, mates, places to live

Sharing resources

Predation, HerbivoryPredators can affect the size of

prey populationsHerbivores can affect size and

distribution of plants

Keystone species

Symbiosis“Living together”Three classes of symbiotic relationships

in nature:MutualismParasitismCommensalism

MutualismMutualism: both partners benefit squid and bioluminescent bacteria

Human gut microbiotaPlant roots and nitrogen fixing bacteria

ParasitismOne organism lives inside or on another,

obtains all it’s nutrients from the host and harms the hostLeechFleas & ticksTapeworm

Commensalism“Commensalism: one organism benefits, the

other is neither harmed nor helped barnacles on gray whaleBird on cow

What about cows?Bacteria in a cow’s stomach break down the

cellulose in grass, gaining nutrientsIs this an example of commensalism or

mutualism?