Chapter 37: ecosystems and communities

Hippos Hippos (herbivores, hairless)  barbels, snails, and shovel-nosed gobis eat the dung  crocodiles eat the fish and snails Microorganisms also feed on the dung and get nutrients which then go to the trees

Competition -/- Ecological niche: biotic + abiotic resources in the environment Occurs when 2 species are present and fight for resources Decreases carrying capacity

Mutualism +/+ Examples: Coral reef and photosynthetic dinoflagellates

Predators +/- Benefits predator, hurts prey Prey uses camoulflage

Herbivory +/- As plants are eaten it must expend E to replace them Defenses: thorns, spines, chemical toxins Coevolution: Heliconius and passion flower vine

Parasites +/- Example: aphids and plants

A food web

Species Diversity 2 components – Species richness – Relative abundance – Species diversity often has consequences for the species living in that community

Keystone species A species whose impact on the community has a large impact on its community Occupies a niche that holds the community in place

Ecological succession Disturbances: events that damage biological communities, remove organisms from them and alter the availability of resources Ecological succession: the disturbed area may be colonized by a variety of species which are gradually replaced by a succession of other species Primary succession: when ecological succession begins in a virtually lifeless area with no soil (ex: new volcanic islands) Secondary succession: where a disturbance has destroyed an existing community but left the soil intact (ex: floods)

Ecological succession Primary successionSecondary succession

Carbon cycle

Phosphorous Cycle

Nitrogen Cycle