AP Biology, Chapter 53
Community Ecology

SUMMARY
INTRODUCTION

EARLY HYPOTHESES OF COMMUNITY STRUCTURE
	Introduction
		1. Explain the relationship between species richness and relative abundance.
			a. Species richness is the number of species in an area
			b. Relative abundance expresses the proportions of individual species
	The interactive and individualistic hypotheses of community structure: science as a 
	process

INTERACTIONS BETWEEN POPULATIONS OF DIFFERENT SPECIES
	Introduction
	Interspecific interactions can be strong selection factors in evolution
		2. Define the process of coevolution.
			a. Species interactions are selective pressures
			b. Coevolution involves adaptation and counteradaptation	
	Interspecific interactions may have positive, negative, or neutral effect's on a 	population's density:  an overview
		3. List four possible specific interactions and explain how the relationships affect the 
		population densities of the two species.
			a. Predation and parasitism: +/-
			b. Competition: -/-
			c. Commensalism: +/0
			d. Mutualism: +/+
	Predation and parasitism are +/- interactions: a closer look
		4. Define and compare predation, herbivory, and parasitism.
			a. Predation: one organism eats some or all of another
			b. Herbivory: the prey is a plant
			c. Parasitism: predtaor lives on or inside the prey 
		5. Relate some specific predatory adaptations to the properties of the prey.
			a. Claws, fangs, mouthparts, poison
		6. Describe the defense mechanisms that evolved in plants to reduce predation by 
		herbivores.
			a. Spines, tough covering, toxic chemicals, camouflage
		7. Explain how cryptic coloration and warning coloration aid an animal in avoiding 
		predators.
			a. Cryptic coloration / shape = camouflage
			b. Warning color: advertisement of effective chemical defenses
		8. Distinguish between Batesian mimicry and Müllerian mimicry.
			a. Batesian mimicry: harmless species resembles one with warning color
			b. Müllerian mimicry: similar warning color convergently gained by 
			harmful species
		9. Describe how predators use mimicry to obtain prey.
			a. Predators may resemble harmless or prey species
	Interspecific competitions are -/- interactions: a closer look
		10. Describe the competitive exclusion principle and explain how competitive exclusion 
		may affect community structure.
			a. Competitive exclusion: species requiring the same limited resource cannot 
			coexist in the same space
			b. One of the species must migrate or die
		11. Define an ecological niche and restate the competitive exclusion principle using the 
		niche concept.
			a. Niche = the sum of a population's use of resources
				i. Fundamental niche = resources a population is capable of using 
				ii. Realized niche = resources a population actually uses
			b. Two species may not simultaneously occupy the same niche 
	Commensalism and mutualism are +/0 and +/+ interactions, respectively: a closer 
	look
		12. Distinguish among parasitism, mutualism, and commensalism.
			a. All three are types of symbiosis (close physical associations)
			b. Differentiated based on +/- benefits
				i. Mutualism both benefit
				ii. Commensalism one benefits the other is neutral
				iii. Parasitism one benefits while the other is harmed

INTERSPECIFIC INTERACTIONS AND COMMUNITY STRUCTURE
	[no objectives]

DISTURBANCE AND EQUILIBRIUM
	Introduction
	Nonequilibrium resulting from disturbance is a prominent feature of most 
	Communities
		13. Describe how disturbances affect community structure and composition. Illustrate 
		this point with several well-studied examples.
			a. Effects
				i. Remove organisms and alter resource availability
				ii. Creates opportunities for species
			b. Examples
				i. Fire in chaparral, grassland, savanna
				ii. Freezing of bodies of water
		14. Give examples of humans as widespread agents of disturbance.
			a. Habitat destruction for agriculture and development
			b. Harvesting of biotic and abiotic factors
			c. Currently affects 60% of Earth's land area
	Humans are the most widespread agents of disturbance
	Succession is a process of change that results from disturbance in 
	communities
		15. Describe and distinguish between primary and secondary succession.
			a. Primary succession starts without soil from glacier retreat or volcanic activity
				i. Weathering
				ii. Moss and lichen
				iii. Grasses and herbs
				iv. Trees where permitted by abiotic factors
			b. Secondary succession occurs where soil is already present from fire or old 
			fields	
			c. No stable climax community because of normal disturbance
	The nonequilibrium model views communities as mosaics of patches at 
	different stages of succession

COMMUNITY ECOLOGY AND BIOGEOGRAPHY
	[no objectives]