COMMUNITY ECOLOGY Honors Biology

OBJECTIVES Describe and give examples for all species interactions and arrange in a graphic organizer Contrast species richness and diversity Describe stages of succession Community are species interacting in a given area

SPECIES INTERACTIONS Symbioses: Close interactions among species Five types Predation Parasitism Competition Mutualism Commensalism

PREDATION Predator captures, kills and consumes prey Natural Selection: Predators: find, capture and consume prey Prey: avoid being captured Flee Hide and camouflage

PREDATION Mimicry: Herbivores eat plants Harmless species resembles poisonous species Poisonous resembles other poisonous Herbivores eat plants Plant adaptations: Physical: sharp thorns, spines, tough leaves Chemical defenses: bad tasting, irritating, poisonous (secondary compounds)

PARASITISM Species interaction where one species is harmed and the other benefits No killing and consuming Parasite and host Ectoparasite: live on body; ticks Endoparasite: live in body: tapeworm

PARASITISM Evolution: Defense mechanisms: skin, chemical protection in openings Parasites: tapeworms absorb through skin

COMPETITION Fundamental niche overlap – use of same resource Competitive exclusion: one species is eliminated from community because of competition for resources

COMPETITION Character Displacement: Resource Partitioning Differences between competitors Beaks on finches Resource Partitioning Each use part of resources Time partitioning

MUTUALISM Both species benefit Ants in the acacia plant Flowers and pollinators

COMMENSALISM One species benefits and other is not affected May not be any true cases Egrets feeding on buffalo

SPECIES RICHNESS AND DIVERSITY Number of species in a community Closer to equator: greater richness Larger areas have more species: species area effect Species Diversity Relative abundance of each species in a community

SUCCESSION Disturbances can trigger a sequence of changes in the composition of a community New species come right in  new species Gradual sequential regrowth of species in an area Pioneer Species: small, fast growing, fast reproducing

PRIMARY SUCCESSION Development where life was never supported Slowly – minerals needed for growth are unavailable

SECONDARY SUCCESSION Replacement of species in area following disruption from natural disaster or human activity Cleared by agriculture or natural disaster Soil intact About 100 years for original return; stages Annual Grasses  Perennial Grasses  shrubs  trees

COMPLEXITY Succession until climax community Organisms alter environment to make it favorable for next organisms