Ch. 52- Introduction to Ecology- Guided Notes
What you must know:
 The role of abiotic factors in the formation of biomes.
 Features of freshwater and marine biomes.
 Major terrestrial biomes and their characteristics.
1. What is Ecology
 Ecology: the scientific study of the interactions between organisms and the environment
 “Richness of the biosphere”
 These interactions:
o Determine both the distribution of organisms and their abundance
 Where organisms are found and how many of them there are.
 Ecology is both observational/descriptive and experimental
o Observational - what’s there and how does it change.
o Experimental - rigorous due to mathematical modeling of populations and ecosystems which
relies on innovative experimental design and statistical inferencing.
 Changes in Ecological time (minutes, months, years) result in changes in Evolutionary time
(decades, centuries, millenia +)
 Predators eat prey, kills off individuals which lowers the population size
(ecological effect) and changes the gene pool (evolutionary effect)
2. Environmental Factors
 The ecological study of species involves biotic and abiotic influences.
o Biotic = living (organisms – behaviors & interactions between organisms)
o Abiotic = nonliving (temp, water, salinity, sunlight, soil)
3. Biogeography: geographic distribution of species
 Factors:
o Dispersal – movement away from area of origin
o Behavior – habitat selection
o Biotic factors – other species, food resources, competition, pollinators, predators
o Abiotic factors – temp, water, oxygen, salinity, sunlight, rocks & soil
4. Dispersal
 Dispersal - the movement of individuals away from their area of origin or from centers of high
population density.
o Natural range expansion
o Cattle egrets
o Early humans “out of Africa”
 Different from migration.
o Species transplants
o Potential vs. actual ranges
o Where organisms could be versus where they are.
 Invasive/introduced species.
o Asian Carp in Mississippi threaten Great Lakes
4. Hierarchy
 Organisms/Species: group of interbreeding individuals that can produce fertile offspring
 Population: group of individuals of same species living in a particular geographic area
 Community: group of populations of different species in an area
 Ecosystem: community of organisms + physical factors
 Landscape: mosaic of connected ecosystems
 Biosphere: global ecosystem
5. Climate
 Climate: long-term prevailing weather
conditions in a particular area
o Climate = temperature + precipitation
+ sunlight + wind
 Macroclimate vs. microclimate:
o Macro: work at seasonal, regional or
local level
o Micro: small-scale environmental
variation (eg. under a log)
 Climate change: some species may not survive
shifting ranges
6. Global Climate Patterns:
 Latitudinal Variations in Sunlight intensity
o Earth’s curved shape causes latitudinal
variation in the intensity of sunlight
o Because sunlight strikes the equator
perpendicularly, the most heat and light
per unit of surface area are delivered
there
o At higher latitudes, sunlight strikes Earth
at an oblique angle, and thus the light
energy is more diffuse on Earth’s
surface
 Air Circulation & Precipitation Patterns

Seasonal Variation in Sunlight Intensity

Ocean Currents

Mountains affect rainfall
7. Biomes
 Biomes: major types of ecosystems that
occupy very broad geographic regions
o Climate and elevation determine biomes
a. Tropical Forest
 distribution: equatorial
 precipitation: very wet
 temperature: always warm
 characteristics: many plants &
animals, thin soil
b. Desert
 distribution: 30°N & S latitude
band
 precipitation: less than 30 cm per
year
 temperature: variable daily &
seasonally, hot & cold
 characteristics: sparse vegetation
& animals, cacti, succulents,
drought tolerant, reptiles, insects,
rodents, birds
c. Savanna
 distribution: equatorial
 precipitation: seasonal, dry
season/wet season
 temperature: always warm
 characteristics: fire-adapted,
drought tolerant plants, herbivores,
fertile soil, between a desert and
rainforest
d. Chaparral
 Distribution: little bit of most of
the continents , coastal
 Precipitation: seasonal, drought
common
 Temperature: very hot and dry
 Characteristic: Most of the plants
have small, hard leaves which hold
moisture. Some of these plants are
poison oak, scrub oak, Yucca
Wiple and other shrubs, trees and
cacti. The animals are all mainly
grassland and desert types
adapted to hot, dry weather.
coyotes, jack rabbits, mule deer,
alligator lizards, horned toads,
praying mantis, honey bee and ladybugs.
e.


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Temperate Grassland
distribution: mid-latitudes, mid-continents
precipitation: seasonal, dry season/wet season
temperature: cold winters/hot summers
characteristics: prairie grasses, fire-adapted, drought tolerant plants; many herbivores; deep, fertile
soil
f. Northern Coniferous Forest/ Taiga
 distribution: high-latitude, northern hemisphere
 precipitation: adequate to dry (temperate rain forest on coast)
 temperature: cool year round
 characteristics: conifers; diverse mammals, birds, insects, etc.
g. Temperate Broadleaf Forest
 distribution: mid-latitude, northern hemisphere
 precipitation: adequate, summer rains, winter snow
 temperature: moderate warm summer/cool winter
 characteristics: many mammals, insects, birds, etc.; deciduous trees; fertile soils
h. Artic Tundra
 distribution: arctic, high-latitude, northern hemisphere
 precipitation: dry
 temperature: cold year round
 characteristics: permafrost, lichens & mosses, migrating animals & resident herbivores
i. Alpine Tundra
 distribution: high elevation at all latitudes
 precipitation: dry
 temperature: cold year round
 characteristics: permafrost, lichens, mosses, grasses; migrating animals & resident herbivores
8. Climograph
 Climograph: plot of
temperature &
precipitation in a
particular region
9. Marine/Aquatic Biomes
 Account for the largest part of the biosphere in terms of area
 Can contain fresh (aquatic; less than 1% saline), brackish, or salt (marine; ≈ 3% saline) water
 Oceans
o Cover about 75% of Earth’s surface
o Have an enormous impact on the biosphere
o Evaporation provides majority of Earth’s rainfall
o Ocean temperatures affect climate and wind patterns
o Algae and photosynthetic bacteria provide oxygen and consume CO2
10. Zonation
 Are stratified into zones or layers defined light penetration, temperature, and depth
 Thermoclines - Narrow vertical zone of abrupt temperature change.
o Photic Zone – sufficient light for photosynthesis
o Aphotic Zone – little light penetration
o Benthic Zone – bottom substrate composed of sand, organic, and inorganic materials (ooze)
o Benthos – Organisms that live in the benthic zone
o Detritus – dead organic matter that rains down from the productive photic zone.
 In aquatic communities organisms are distributed according to:
o water depth
o light penetration
o distance from the shore
o open water versus benthic zone
11. Nutrient Turnover
 Lakes and other marine/aquatic biomes experience turnover.
a. Lakes
 Oligotrophic - nutrient poor, oxygen rich
 Eutrophic - nutrient rich, oxygen poor
 Periodic oxygen depletion; large amount of decomposition
 Biota - fish, invertebrates depending on O2 levels, phyto- and zooplankton.
b. Wetlands
 Inundated with water at least periodically
 Plants adapted to water-saturated soil
 Highly productive
 Important filters and breeding grounds
 Birds, carnivores, crustaceans, plants, reptiles.
c. Streams & Rivers
 Current with lots of aeration
 Aquatic plants and phytoplankton, fish, invertebrates, etc.
o Ex. Potomac and Anacostia rivers, Rock and Sligo creeks, Chesapeake Bay watershed.
d. Estuaries
 Transition between rivers and sea - brackish water with flow between the two.
 Variable salinity depending on temperature, depth, and tides.
 Worms, oysters, crabs, fish, etc.
 Highly productive and important in filtering water.
e. Intertidal Zones
 Periodically submerged and exposed.
 Physical environment varies vertically, so species range varies vertically.
 Oxygen and nutrients renewed tidally.
 Sea grass, algae, worms, crustaceans, crabs, etc.
f. Oceanic Pelagic Zone (Open Water)
 Open ocean, particularly deep water.
 Driven by currents - lots of light and oxygen. Large photic zone.
 Experience nutrient turn over - depends on temperature.
 70 percent of world’s surface
 Phytoplankton and photosynthetic bacteria - makes our oxygen!
 Zooplankton, fish, cephalopods, marine mammals, etc.
g. Coral Reefs
 Formed from coral “skeletons”
 Photic zone - zooxanthellae need light for photosynthesis; sensitive to change in temperature
 Fringing reef --> barrier reef --> atoll island
 Unicellular algae, coral animals, fish and invertebrate diversity.
h. Marine Benthic Zone
 Below neritic (near, coastal) and pelagic (noncoastal, open water) zones.
 Deep benthic = abyssal zone; deep sea vents with chemoautotrophs.
 Shallow benthic - oxygen from algae and seaweed.
 Chemo- or photoautotrophs; worms, arthopods, echinoderms, etc.
Warm Up Questions
1. Dead organic matter that rains down from the productive photic zone.___________________
2. The movement of individuals away from their area of origin or from centers of high population
density___________________________
3. Nutrient rich, oxygen poor lake.________________
4. Long term weather patterns on a global, regional and local level. ____________________________
5. What are the 4 factors that affect aquatic communities distribution of organisms
6. Name examples of biotic and abiotic factors in the environment surrounding PPHS.
7. Which biomes can be found in Colorado?
8. Define the following terms:
a. population
b. community
c. ecosystem
d. biosphere