AP Biology, Chapter 50
An Introduction to Ecology and the Biosphere

SUMMARY
INTRODUCTION

THE SCOPE OF ECOLOGY
	Introduction
	Ecology is the scientific study of the interactions between organisms and their 
	environment
		1. Define ecology.
			a. Scientific study of the interactions between organisms and their environment
		2. Why are mathematical models and computer simulations especially important in the 
		study of ecology?
			a. Complex: many interacting variables
			b. Difficult to experimentally control
			c. May be unethical to perform controlled experiments
		3. Distinguish between the abiotic and biotic components of the environment.
			a. Abiotic: non-living; pH, chemical nutrients, humidity, temperature
			b. Biotic: living; competition, predation, parasitism
	Ecological research ranges from the adaptations of organisms to the dynamics 
	of ecosystems
		3. Distinguish among organism, population, community, ecosystem, and biospheric 
		sciences.
			a. Organism: an individual living thing
			b. Population: breeding group of a species in a particular area
			c. Community: all organisms in a particular area
			d. Ecosystem
				i. Abiotic and biotic factors in an area
				ii. Important for the study of energy flow and chemical cycling  
	Ecology provides a scientific context for evaluating environmental issues

ABIOTIC FACTORS OF THE BIOSPHERE
	Introduction
	Climate and other abiotic factors are important determinants of the 
	biosphere's distribution of organisms
		4. Describe abiotic factors that affect the distribution of organisms.
			a. Examples: temperature, water, sunlight, wind, rocks and soil, periodic 
			disturbances
			b. Major determining abiotic factors
				i. Temperature affects metabolic rates
				ii. Precipitation provides water
		5. Identify major trends in the variability of abiotic factors.
			a. Degree of variability
				i. More constant in water, along coasts, and near the equator
				ii. More variable windward/leeward, farther from equator
			b. Causes of variability
				i. Seasons: tilt of the Earth
				ii. Latitude: angle of the Sun
				iii. Altitude: the colder and drier the higher
				iv. Topography: wind and water and water flow over and around
		6. Describe how the process of global air circulation maintains latitudinal climatic zones.
			a. Sun's energy is strongest at the equator
			b. Tropical air rises, cools, rains out
			c. Air is drawn to the equator at the surface
			d. Dry air flows away from the equator aloft

AQUATIC AND TERRESTRIAL BIOMES
	Introduction
	Aquatic biomes occupy the largest part of the biosphere
		5. Distinguish among the vertical layers found in aquatic biomes.
			a. Photic: light for autotrophs
			b. Aphotic: no light, no living autotrophs
			c. Thermocline: sharp boundary between warm upper and cold lower
			d. Benthic: entire bottom supplied with detritus
		6. Define and compare the prominent freshwater biomes.
			a. Littoral: freshwater shore with rooted plants
			b. Stream
				i. Adaptations for the current
				ii. Energy from shore plants and detritus
			c. Lake/pond
				i. Oligotrophic: deep, clear, nutrient-poor
				ii. Eutrophic: shallow, murky, nutrient-rich
		7. Differentiate wetlands and estuaries.
			a. Wetland has little open water; mainly covered with aquatic plants
			b. Estuaries are where freshwater enters saltwater; surrounded by wetlands
		8. Define and compare the prominent marine biomes.
			a. Intertidal
				i. Alternately exposed and submerged; subject to wave action
				ii. Very stratified on rocky substrates
			b. Coral reef
				i. Warm tropical clear water
				ii. Autotrophs: encrusting and symbiotic algae
			c. Oceanic pelagic
				i. Lower nutrients farther from shore
				ii. In temperate zones, upwelling brings nutrients
				iii. Phytoplankton are the major autotrophs
			d. Deep sea vent
				i. Vents release very hot water with H2S
				ii. Chemoautotrophs form the base of food chains
	The geographical distribution of terrestrial biomes is based mainly on regional 
	variations in climate
		9. Describe the characteristics of the major terrestrial biomes: tropical forest, 
		savanna, desert, chaparral, temperate grassland, temperate forest, taiga, and 
		tundra.
			a. Tropical forest
				i. Equatorial: consistent high temperature and rainfall
				ii. Consistent conditions allow more specialization
			b. Savanna
				i. = tropical grassland; seasonal dryness and fire 
				ii. Many large grazers
			c. Desert
				i. Driest and warmest
				ii. Plants adapted for saving water; nocturnal, burrowing animals
			d. Chaparral
				i. Dry with dense, spiny evergreen shrubs
				ii. Periodic fires
			e. Temperate grassland
				i. Seasonally too dry for trees
				ii. Periodic fires
			f. Temperate forest
				i. Dominated by deciduous trees; many adaptations for seasonal survival
				ii. Vertically layered
			g. Taiga
				i. Coniferous forest; conical trees shed heavy snow
				ii. North or higher than temperate forest
			h. Tundra
				i. Cold and dry; swampy in warm season
				ii. Permafrost limits tree root penetration 
		10. Account for the similarity in life forms found in the same type of biome in 
		geographically separated areas.
			a. Similar abiotic factors; analogous adaptations
			b. = convergent evolution

CONCEPTS OF ORGANISMAL ECOLOGY
	Introduction
	The costs and benefits of homeostasis affect an organism's responses to 
	environmental variation
		11. Contrast regulators and conformers.
			a. Regulators expend energy to maintain homeostasis
				i. For example, endotherms
				ii. Can involve behavioral and physiological mechanisms
				iii. Allows survival in variable environments
			b. Conformers allow their internal conditions to vary with their surroundings
				i. For example, ectotherms
				ii. Requires less energy
				iii. Common in organisms living in stable environments
		12. Define the principle of allocation and contrast the energy budgets of regulators and 
		conformers.
			a. Principle of allocation
				i. Organisms have an energy budget
				ii. Energy available after basic needs are met may be allocated for 
				growth or reproduction
			b. Conformers vs. regulators
				i. Conformers don't use as much energy for homeostasis, have more 
				to allocate
				ii. Regulators use more, have less to allocate
	An organism's short-term responses to environmental variations operate 
	within a long-term evolutionary framework
		13. Differentiate the short-term and long-term responses of organisms and species to 
		environmental change.
			a. Short-term
				i. Behavioral: move into the sun
				ii. Morphological: close stomata
				iii. Physiological: allow more water to pass through kidney
			b. Long-term
				i. Behavioral: migration
				ii. Evolutionary: species develop new traits 
		14. Define acclimation and describe how acclimation affects the tolerance limits of 
		organisms.
			a. Acclimation is a reversible shift in an organism's tolerance curve
			b. Allows organisms to tolerate a wide range of conditions and habitats