Global Circulation Patterns


explain the forces that drive global circulation patterns and how those patterns determine weather and climate.

  • Explain the difference between weather and climate
  • List the layers of the atmosphere starting at the Earth’s surface and moving up
  • Identify the temperature differences between each layer and the science behind these differences
  • List the important traits of each layer as it pertains to the environment and humans
  • Explain how the tilt of the Earth relates to seasons and identify the Earth’s position for each season in the Northern hemisphere
  • Define albedo and identify areas on the earth with low and high albedo
  • Define adiabatic heat and adiabatic cooling and connect each to convection currents
  • Identify the location of Hadley and polar cells on a globe
  • Explain the effect Hadley cells and polar cells have on global climate
  • Explain what the Intertropical Convergence Zone (ITCZ) is and its connection to weather
  • Describe the Coriolis Effect and use it to determine global wind patterns
  • Define gyres and identify their role in global climates
  • Connect upwellings to ocean productivity
  • Explain the science behind thermohaline circulation
  • Identify the differences in ocean temperatures and weather based on El Nino
  • Identify the properties on different sides of a mountain based on the rain shadow effect and know the science behind why the rain shadow effect occurs

In Class Questions: We will do these together in class.

There are 7 major components to the distribution of heat and precipitation (and thus climates) on Earth:

  1. Earth’s Atmosphere
  • Explain why atmospheric pressure decreases as altitude increases.

○ Gravitational pull weakens the further away you move from earth so molecules are more densely packed and have higher pressure closer to earth

○ Pressure is like the weight of air molecules above you, and as you get higher up into the layers of the atmosphere, there are less air molecules pushing you down

  • Identify which of the 5 layers of Earth’s atmosphere fit each description in the table:


Aurora Borealis (northern lights) occurs here


Atmospheric pressure is highest here


All weather occurs here


Atmospheric pressure is lowest here


Atmospheric temperatures are highest here


Contains the ozone layer


Layer closest to the surface


Densest layer of the atmosphere


Outermost layer of the atmosphere


Temperature is around 20° at this layer’s lowest point


The lowest pressure is found in this layer

  • The chemical formula for ozone is O3 and its function is to absorb UV-B and UV-C radiation
  1. Unequal Heating of Earth
  • Explain how each of the following factors creates unequal heating of Earth’s surfaces:
  • Angle of sun to surface: the sun’s rays strike the region nearest the equator at a right angle, and in the mid and polar regions of earth the sun’s rays strike at a more oblique angle...sun’s rays travel a shorter distance through the atmosphere when going to the equator...also more atmosphere around mid latitude and polar regions to get through

○ Solar rays per unit area: right angle that the sun’s rays hit the tropics at causes solar energy to be distributed over a smaller surface area than it would be in higher regions

○ Albedo: some areas of earth reflect more solar energy than others, white surfaces reflect more, dark/black surfaces absorb more

  • How will the melting of polar ice from global warming alter Earth’s albedo?
    • There will be more absorption everywhere and way less reflection, therefore way less albedo
  • Generally speaking, the tropical regions of Earth receive the most light/heat in a year and the polar regions receive the least light/heat in a year.
  1. Atmospheric Convection Currents
    • Explain why warm air rises and cool air sinks.
      • Warm air has a lower density than cool air ○ The density of air determines its movement Why is rising air associated with precipitation?

○ Warm air (rises) and has a higher capacity for water vapor than cool air creating humidity on hot days

○ When air cools and its saturation point drops water vapor condenses into liquid water to form clouds and then precipitation can occur

  • What types of atmospheric conditions are found where air sinks back to the surface?
    • Sinking air has an increasing pressure, air decreases in volume and has a higher temperature

○ Adiabatic heating creates thunderstorms and tornados ● Draw each of the following on the diagram below:

  • Earth’s atmospheric convection cells, with direction of air movement
  • The general level of precipitation found at each latitude belt: 0/30/60/90
    • 0: wet throughout the year

○ 30: wet winter, dry summer

○ 60: wet summer, dry winter

○ 90: dry all year

  • Why does the ITCZ move throughout the year in a regular pattern?
    • The earth is tilted and rotating around the sun, so the ITCZ moves north and south of the equator following the sun’s most direct rays
  1. Earth’s Rotation and the Coriolis Effect
    • The Coriolis Effect deflects moving objects (such as wind) in a clockwise direction in the northern hemisphere and a counterclockwise direction in the southern hemisphere
    • Draw arrows indicating the general direction of wind movement between latitudes :
  1. Earth’s Tilt and Seasons
    • In Los Angeles, the longest day of the year occurs in the month of June because…...during this time the northern hemisphere is maximally tilted towards the sun and experiences the longest day of the year, summer begins
    • Why does the northern hemisphere’s summer come during the southern hemisphere’s winter, and vice versa?
      • earth’s axis of rotation is tilted at a 23.5 degree angle so the northern and southern hemispheres experience different levels of sunlight seasonally as the earth rotates around the sun at its tilted angle
  1. Ocean Currents
    • What are gyres, and how are they created?
      • Large scale patterns of water circulation

○ The effect of trade winds and the coriolis effect on the northern and southern hemispheres ● Explain how oceanic gyres and atmospheric convection currents redistribute heat around Earth.

○ Cold water from the polar regions moves along the west coasts of continent, and the transport of cool air immediately above these waters causes cooler temperatures on land

○ Warm air from the tropics moves along the east coast of continents, and the warm air from above these water sources causes warmer temperatures

  • Upwelling is a process in which deep water is brought to the surface along a coast. It is caused by diverging surface currents that separate from one another and leave room for new water to rise and replace it and is important to humans because deep water bring nutrients from the ocean bottom that support large population of producers, that support large populations of fish .
  • Describe what thermohaline circulation is, and how it transports heat.
    • An oceanic circulation pattern that drives the mixing of surface water and deep water

○ Driven by surface waters that contain unusually large amounts of salt

○ Warm currents flow from warm regions to extremely cold regions

○ Some of this water freezes or evaporates, and the salt that remains behind increases the salt concentration in the water

○ This cold, salty water is relatively dense so it sinks to the bottom of the ocean mixing with deeper ocean waters

○ This sinking of cold salty water at high latitudes and rising of warm water near the equator creates the movement necessary to drive a deep, cold current around the world

  • The ENSO is a disruption to winds and ocean currents in which warm water and increased precipitation build up in the region of the southeastern United States while drought and cold water occur in the region of southern Africa and southeast Asia
  1. Rain Shadows
    • What is the difference between the windward and the leeward sides of a mountain range?
      • The windward side faces the wind, adiabatic cooling, rain ○ Leeward side: adiabatic heating, dry and arid

Summarize why latitude is so important in determining climate:

Latitudes have different closeness to the sun bc of the earth’s tilt, they also experience different wind patterns and oceanic currents which make precipitation and temperature vary drastically

Biomes pp. 87-114

describe the major terrestrial biomes.

  • Correctly identify biomes on the Whittaker diagram based on their average temperature and annual precipitation
  • Label biomes on a map of the world
  • Identify the growing season on a climate diagram and explain why the growing season occurs during that time period
  • List the major characteristics and unique terms that apply to the following biomes and the reasons behind the characteristics
    • Tundra

■ Arctic, antarctic, alpine

■ Permafrost

■ Poorly developed soil, found at high latitudes or low latitudes, short growing season, low productivity

○ Boreal Forest

■ Taiga, coniferous

■ Nutrient poor and acidic soils because of falling needles, only found in northern hemisphere, moderate productivity

○ Temperate Rainforest

■ Coastal redwoods

■ Rocky, acidic soils

■ Coastal biome

■ Oceans moderate temperature and provide water vapor for precipitation

○ Temperate Seasonal Forest

■ Temperate deciduous forest

■ Fertile soils, rich in organic material from seasonal decomposition of leaves

■ Long growing season

■ Moderately high productivity

○ Woodland/Shrubland

■ Chaparral, matorral, mallee, fynbos, maquis

■ Thin, nutrient poor soils because of leaching by winter rains

■ Also called chaparral, climate described as Mediterranean ■ Periodic wildfires

○ Temperate Grassland/Cold Desert

■ Prairies, pampas, steppes

■ Tallgrass prairies, shortgrass prairies, cold deserts, temperate deserts

■ Fertile soils

■ Dry, windy conditions cause fires that prevent tree growth ■ Productive

○ Tropical Rainforest

■ ITCZ, canopy, understory, subcanopy, epiphytes, lianas

■ Thin, nutrient poor soils

■ Rapid decomposition and quick uptake of nutrients

■ Seasons depend on location of ITCZ

■ Most productive land biome

○ Tropical Seasonal Forest/Savanna

■ Tropical deciduous forest, savanna

■ Fertile soil compacted by grazing animals

■ Seasons due to moving ITCZ

■ Large herds of migrating animals follow seasonal precipitation

○ Subtropical Desert

■ Hot deserts

■ Soil rich in minerals but poor in organic material

■ Low resistance and resilience

■ Low diversity

■ Very low productivity

describe the major aquatic biomes.

  • Explain the properties of a lake and stream that make it different than a lake
    • Lakes have standing water while streams have flowing water
  • Label the parts of a lake and the properties of each part
    • Littoral: shallow area of soil and water near the shore where algae and emergent plants grow, photosynthesis occurs there

○ Limnetic: rooted plants can no longer survive, phytoplankton is here, open water, extends as deep as sunlight penetrates

○ Profundal: very deep region, no sunlight can penetrate this zone, producers can’t survive here, bacteria decompose detritus

○ Benthic: muddy layer on the bottom

  • Identify the different types of wetlands and the vital roles wetlands play in the environment
    • Freshwater

■ Swamps: wetlands that contain emergent trees

■ Marshes: contain primarily non woody vegetation including cattails and sedges

■ Bogs: very acidic wetlands that contain sphagnum moss and spruce trees

○ Support species of plants that are specialized to live in submerged or saturated soils

○ Among the most productive biomes on the planet

○ Ecosystem services:

■ take in large amounts of rainwater and release it slowly into the groundwater through nearby streams, reduce severity of floods and droughts

■ Filter pollutants from water

■ Bird species depend on them

  • Identify the unique properties of salt marshes and their importance to the greater environment
    • One of the most productive biomes in the world

○ Many found in estuaries where freshwater from rivers mixes with salt water from the ocean

○ Abundant plant life helps filter out contaminates in the water

○ Provide habitat for spawning fish and shellfish

  • Explain the importance of mangroves to coastlines
    • Help protect coastlines from erosion and storm damage

○ Nutrient rich environment from falling leaves and trapped organic material

○ Provide sheltered habitat for shellfish and fish

  • Identify the types of organisms that live in an intertidal zone and explain why those organisms must have unique adaptations
    • Goes from a relatively stable biome at high tide to a quite harsh environment at low tide when organisms are exposed to direct sunlight, high temperatures, and desiccation

○ Waves crashing

○ Barnacles, sponges, algae, mussels, crabs, and sea stars

  • Explain the importance of coral reefs to humans
    • Coral reefs are a huge area of biodiversity and are the habitat to many kinds of fish

○ Corals can be used to make medicine

○ Huge source of economic value from tourism to many countries

○ Protect land from erosion and protect wetlands

  • Describe the organisms that makeup coral and also the diversity of other organisms in the reef ○ Tiny animals that secrete a layer of limestone to form their internal skeleton
    • It is a hollow tube with tentacles

○ Single celled algae live within their tissues

○ Home to many different kinds of fish and invertebrates, anemones

  • Explain what coral bleaching is, what causes it, and what its effects would be if it occurs
    • Pollutants, disease, environmental changes, lower pH, and higher water temperatures cause the algae inside the corals to die which makes the corals die and the reefs turn white ○ It endangers the entire coral biome which has tons of biodiversity and nutrient cycling
  • Label the zones of the open ocean and list the properties of each zone
    • Photic: upper layer of the ocean that receives enough sunlight to allow photosynthesis

○ Aphotic: deepest layer of water that lacks sufficient sunlight for photosynthesis ○ Benthic: ocean floor



The average weather that occurs in a given region over a long period of time..typically over several decades


The layer closest to the earth’s surface, extending up to approximately 16 km and containing most of the atmosphere’s nitrogen, oxygen, and water vapor


The layer of the atmosphere above the troposphere, extending roughly 16-50 km above the surface of the earth


The percentage of incoming sunlight that is reflected from a surface

Saturation Point

The maximum amount of water vapor that can be in the air at a given temperature

Adiabatic Cooling

As air rises in the atmosphere, the pressure on it decreases. The lower pressure allows the rising air to expand in volume, and this expansion lowers the temperature of the air

Adiabatic Heating

When air sinks toward earth’s surface, the pressure on it increases. The higher pressure forces the air to decrease in volume, and this decrease raises the temperature of the air

Latent Heat Release

When water vapor in the atmosphere condenses into liquid water and energy is released

Hadley Cell

Convection currents that cycle between the equator and 30 degrees N and S

Intertropical Convergence Zone

The area of the earth that receives the most intense sunlight where the ascending branches of the two Hadley

cells converge. Dense clouds and intense thunderstorm activity

Polar Cells

Convection currents formed by air that rises at 60 degrees N and S and sinks at the poles

Coriolis Effect

Deflections of objects paths in the

northern and southern hemispheres

due to earth’s rotation


Large scale patterns of water circulation


Deeper waters rise up and replace water that diverges from surface currents

Thermohaline Circulation

The oceanic circulation pattern that drives the mixing of surface water and deep water across the whole world, crucial for moving heat and nutrients

El Nino-Southern Oscillation (ENSO)

Periodic changes in wind and ocean currents that create cooler, wetter conditions in the southeastern US and unusually dry weather in southern africa and southeast asia

Rain Shadow

Occurs when humid winds blowing inland from the ocean meet a mountain range. On the windward side, there is lots of precipitation and lots of lush vegetation. On the leeward side, adiabatic heating causes dry and arid conditions


The categorization of terrestrial geographic regions that have similar plant growth forms in areas possessing similar temperature and precipitation patterns


A cold and treeless biome with low growing vegetation


Underlying subsoil in the tundra biome that is an impermeable and permanently frozen layer that prevents water from draining and roots from penetrating

Boreal Forest

A forest made up of primarily coniferous evergreen trees that can tolerate cold winters and short growing seasons

Temperate Rainforest

A coastal biome typified by moderate temperatures and high precipitation

Temperate Seasonal Forest

A biome with warmer summers and colder winters than temperate rainforests and dominated by deciduous trees

Shrubland (Chaparral)

A biome characterized by hot, dry summers and mild, rainy winters

Temperate Grassland/Cold Desert

A biome characterized by cold, harsh, winters, and hot, dry summers

Tropical Rainforests

A warm and wet biome found between

20 N and 20 S of the equator, with little

seasonal temperature variation and

high precipitation

Tropical Seasonal Savannahs



A biome marked by warm temperatures and distinct wet and dry seasons

Subtropical Deserts

A biome prevailing at approximately 30 N and 30 S with hot temperatures, extremely dry conditions, and sparse vegetation

Littoral Zone

The shallow area of soil and water near the shore where algae and emergent plants such as cattails grow, most photosynthesis occurs here

Limnetic Zone

Open water where rooted plants can no longer survive and phytoplankton are the only photosynthetic organisms


Floating algae

Profundal Zone

Region in very deep lakes that isn’t reached by sunlight, producers can’t survive here

Benthic Zone

The muddy layer of a lake or pond beneath the limnetic and profundal zones

Freshwater Wetlands

Aquatic biomes that are submerged or saturated by water for at least a part of each year, but shallow enough to

support emergent vegetation throughout

Salt Marsh

Found along the coast in temperate climates, contain nonwoody emergent

vegetation, one of the most productive biomes in the world

Mangrove Swamps

Occur along tropical and subtropical coasts, they contain trees whose roots

are submerged in water and are salt tolerant

Intertidal Zone

The narrow band of coastline that exists between the levels of high tide and low tide

Coral Reefs

Found in warm, shallow waters beyond the shoreline, represent earth’s most diverse marine biome

Coral Bleaching

A phenomenon in which the algae inside the corals die which makes the corals soon die as well, and then the reefs turn white

Photic Zone

The upper layer of water in the ocean that receives enough sunlight to allow photosynthesis

Aphotic Zone

The deeper layer of water in the ocean that lacks sufficient sunlight for photosynthesis


What happens when some species of bacteria in the aphotic zone use energy contained in the bonds of methane and hydrogen sulfide, which are both found in the deep ocean, to generate energy

Review Exercise: Biome Booklets

Chapter 5 Ecosystem Diversity : pp. 119-140


explain the concept of biodiversity and how it is measured.

  • Differentiate between ecosystem, species and genetic diversity.
    • Ecosystem: within a given region, the variety of ecosystems

○ Species: within a given ecosystem, the variety of species

○ Genetic: within a given species, the variety of genes

  • List the number of species named and number of species estimated on Earth.
    • Species named: almost 2 million

○ Species estimated: 5-100 million but probably about 10 million

  • Define species richness and species evenness. Give an example of an area with high richness and low evenness, high richness and high evenness, low richness and high evenness, etc.
    • Species richness: the number of species in a given area, such as a pond, the canopy of a tree, or a plot of grassland, used to give an approximate sense of biodiversity of a place

○ Species evenness: tells us whether a particular ecosystem is numerically dominated by one species or whether all of its species have similar abundances

○ High richness and low evenness: 199 grizzly bears, 1 black bear

○ High Richness and high evenness: 100 grizzly bears and 100 black bears

○ Low richness and high evenness: 1 black bear and 1 grizzly bear

  • Describe why scientists use phylogenies and interpret a phylogenetic tree.
    • When scientists organize species into categories that indicate how closely related they are to one another the branching patterns of evolutionary relationships are called phylogenies

○ Help scientists establish which species are related based on morphology, behavior, and genetic similarity

  • describe the ways in which evolution can occur.
    • Microevolution: evolution below the species level

○ Macroevolution: when genetic changes give rise to new species or to new genera, families, classes, or phylas

○ Speciation: the evolution of a new species

○ Artificial selection, natural selection, random processes ● Differentiate and give examples of micro and macro evolution.

○ Microevolution of different varieties of apples

○ Macroevolution: ape to human

  • Describe how mutations occur and how they can affect offspring.
    • A mutation is an occasional mistake in the copying process of DNA that produces a random change in the genetic code

○ Environmental factors like ultraviolet radiation can also cause mutations

○ Most mutations are detrimental but some are good

○ They can cause offspring to die before they are born or be more susceptible to predators

  • Define genotype and phenotype and give one example of each. Are phenotypes only determined by an organism’s genes?
    • Genotype: the complete set of genes in an individual, blueprint for the complete set of traits that an organism can potentially possess

■ Genes responsible for eye color

○ Phenotype: actual set of traits expressed in the individual, product of environment as well as genotype

■ Water fleas born with relatively large tail spines and large heads when they are in the presence of predators, but smaller when predators aren’t there

  • Define and describe examples of evolution by artificial selection (examples to know: dog domestication, edible plants from mustard, herbicide/antibiotic resistant organisms).
    • Artificial selection: humans influence evolution by breeding plants and animals for the traits we desire

■ All breeds of domesticated dogs belong to the same species of gray wolf, canis lupus, but dogs exist in an amazing variety of shapes and sizes

■ Starting with a single species of wild mustard, brassica oleracea, plant breeders produced a variety of food crop including cabbage, cauliflower, broccoli, brussels sprouts, kale, and kohlrabi

■ Farmers often use herbicides to kill weeds, but the more we do that, the more we have a chance of a single weed mutating to survive the herbicide and passing the resistance to its offspring

■ In hospitals, the same use of antibiotics and antibacterial cleaners has caused artificial selection of harmful drug resistant bacteria Explain evolution by natural selection and include Darwin’s 5 key ideas.

  • The environment determines which individuals survive and reproduce
  • Certain combinations of traits make individuals better able to survive and reproduce so the genes that produce those traits are more common in the next generation
  • Individuals produce an excess of offspring
  • Not all offspring can survive
  • Individuals differ in their traits
  • Differences in traits can be passed on from parents to offspring
  • Differences in traits are associated with differences in the ability to survive and reproduce
  • Define fitness and adaptations and explain how they both relate to each other.

○ Natural selection favors any combination that improves an individual’s fitness

○ Traits that improve an individual’s fitness are called adaptations

○ Fitness is an organism's ability to survive and reproduce

  • Explain evolution by random processes including mutation, genetic drift, bottleneck effect and founder effect.
    • Processes not based on fitness

○ Mutation

■ Arises in a population and if it’s not lost can increase frequently over time

○ Genetic drift

■ Larger populations aren’t as affected by this

■ In smaller populations, some genotypes can be lost by chance and the genetic composition can change over time

■ Result of random mating

○ Bottleneck effect

■ If a population experiences a drastic decrease in size, some genotypes will be lost, and the genetic composition of survivors will differ from the composition of the original group

■ Result of habitat loss, natural disaster, hunting, or changes in the environment ■ Makes it more difficult for the new population to adapt and reproduce

○ Founder effect

■ If a few individuals from a mainland population colonize an island, the genotypes on the island won’t represent all of the genotypes found on the mainland

■ The island population will look different and pass down different traits ■ Change in population descended from a very small number of founders ● explain how environmental change affects speciation and extinction.

○ It leads to macroevolution

Define geographic isolation and give examples.

■ Physical separation of a group of individuals from others of the same specie

○ A river changes its course and a large lake forms two smaller lakes or a new mountain range rises

○ Genotypes of isolated populations might diverge over time

○ A group of birds colonizing a new island created by volcanic eruption

○ If two habitats differ in environmental conditions such as temperature, precipitation, or the occurrence of predators, natural selection with favor different phenotypes in each of the habitats

○ If there is no movement between the isolated populations, they will become more genetically distinct

  • Define reproductive isolation.
    • When populations become so different that even if the physical barrier were removed, they could no longer interbreed to create viable offspring

○ At this point speciation occurs

  • Describe how allopatric speciation occurs.
    • Through geographic speciation and natural selection

○ Divided species adapt to their own separate environments

○ Reproductive isolation occurs

  • Define sympatric speciation and explain the role polyploidy plays.
    • The evolution of one species into two species in the absence of geographic isolation

○ Polyploidy: number of chromosomes increases to 3, 4 or 6 sets instead of two during the division of reproductive cells

  • Explain the relationship between the pace of evolution and rate of environmental change, genetic variation, population size, and generation time.
    • A slowly changing environment gives species more time to adapt to the changes

○ To survive rapid environmental change, a population must evolve quickly

○ Less genetic variation means there is less chance for the species to adapt to changing conditions

○ If beneficial mutation occurs, it can spread more rapidly in a small population than a large population

○ Small populations usually have less genetic variation than larger ones and are more likely to go through rapid evolution through genetic drift

○ Shorter generation times increase the chance that beneficial mutations will occur within a given amount of time and allow them to spread throughout a population faster

  • Describe the process of genetic engineering to create genetically modified organisms. Give several examples.
    • Scientists can copy genes from a species with some desirable trait, such as rapid growth or disease resistance

○ Scientists then insert these genes into other species to produce GMOs

○ When the GMOs reproduce they pass on the inserted gene to their offspring

○ A soil bacterium naturally produces an insecticide, so plant breeders identify the bacterial genes responsible for making the insecticide, copy those genes, and insert them into their own crops ( Bt-corn and Bt- cotton)

○ Much faster than natural selection

  • Identify three reasons why a species might go extinct.
    • There may be no favorable environment that is geographically close enough to move to

○ The favorable environmental region could already be occupied by a species that the moving species cannot survive competing with

○ An environmental change could occur so rapidly that the species doesn’t have time to evolve new adaptations


Ecosystem Diversity

Within a given region, the variety of ecosystems

Species Diversity

Within a given ecosystem, the variety of species

Genetic Diversity

Within a given species, the variety of genes

Species Richness

The number of species in a given area

Species Evenness

Tells us whether a particular ecosystem is numerically dominated by one species or whether all of its species have similar abundance


The branching patterns of evolutionary relationships


Change in the genetic composition of populations over time


Evolution below the species level


When genetic changes give rise to new species


Physical locations on chromosomes within each cell of an organism, determine the range

of possible traits for an organism that it can pass down to its offspring


The complete set of genes in an individual


An occasional mistake in the copying process of DNA that creates a random change in the genetic code


Occurs as chromosomes are duplicated during reproductive cell division and a piece of one chromosome breaks off and attaches to another chromosome


The actual set of traits expressed in an individual

Artificial Selection

When humans determine which individuals breed, typically with preconceived sets of traits in mind

Natural Selection

The environment determines which

individuals survive and reproduce


An organism’s ability to survive and reproduce


Traits that improve an organism’s fitness

Genetic Drift

A change in the genetic composition of a population overtime as the result of random mating

Bottleneck Effect

A reduction in the genetic diversity of a population caused by a reduction in its size

Founder Effect

A change in population descended from a small number of colonizing individuals

Geographic Isolation

Physical separation of a group of individuals from others of the same specie

Reproductive Isolation

When two species become so different that even if the physical barrier were removed, they would no longer interbreed and produce viable offspring

Allopatric Speciation

The process of speciation that requires geographic isolation

Sympatric Speciation

The evolution of one species into two species in the absence of geographic isolation

Genetic Engineering

Techniques that allow scientists to copy genes from one species with a desirable trait, and insert them into another species

Genetically Modified


An organism produced by copying genes from a species with a desirable trait and inserting it into another species

Range of Tolerance

Limits to the abiotic conditions organisms can tolerate such as extremes of temperature, humidity, salinity, and pH

Fundamental Niche

The suite of ideal abiotic conditions for an organism

Realized Niche

The range of abiotic and biotic conditions under which a species actually lives

Species Distribution

The areas of the world in which a species lives

Niche Generalists

Organisms that can live in a variety of habitats or feed on a variety of species

Niche Specialists

Organisms specialized to live in a specific habitat or feed on a small group of species


The remains of organisms that have been preserved in rocks

Mass Extinction

Periods in which large numbers of species went extinct over relatively short periods of time

Sixth Mass Extinction

Human caused extinction on par with the others occurring over the past two decades

In Class Questions: We will do these together in class.

  1. How do each of the following types of biodiversity support healthy ecosystem function:
    • Genetic diversity – helps species survive adaptations as their environments change

○ Species diversity – helps ecosystem prosper, recycle nutrients, creates different ecosystems

○ Ecosystem diversity – provides ecosystem services like food through photosynthesis, provisioning of water, energy, seafood, lumber, regulating through filtration of water or decomposition of detritus, and cultural experiences

  1. What is the current estimate for the total number of species on Earth, and why is it so hard to get an accurate count?
    • Between 5-100 million, but probably 10 million

○ Lots of species are difficult to find, only active at night, inaccessible in the depths of the ocean, or require a microscope to be seen

  1. What is the difference between species richness and species evenness?
    • Richness determines how many species are in an area, while evenness explains if a particular ecosystem is numerically dominated by one species or whether all of the species have relative abundance

○ Evenness explains species diversity more thoroughly

  1. Explain how genetic diversity is created through evolution:
    • Through mutations or recombinations
  2. In artificial selection, humans induce evolution in a species over time through our actions. What dictates changes in species in the process of natural selection?
    • Natural selection favors any combination of traits that improve an individual’s fitness

○ The environment determines which individuals adapt and reproduce

  1. List 4 organisms and describe the adaptations that increase their fitness in their environment:
    1. The old man of the desert cactus has hairs that reduce water loss
    2. The mammillaria cactus has a large taproot to draw water out of the soil
    3. The waxy outer layers of aloe vera reduce water loss
    4. Water fleas born in a pond with predators have larger heads and spines to protect themselves better
  2. Complete the following chart regarding evolution through random processes:




Effects on genetic diversity?


An occasional mistake in the copying process of DNA that creates a random change in the genetic code

Can be lost or increase in frequency and create more genetic diversity

Genetic drift

A change in the genetic composition of a

population overtime as the result of random mating

In a large population remains the same, in a small population decreases diversity drastically

Bottleneck Effect

A reduction in the genetic diversity of a population caused by a reduction in its size

Genetic composition of survivors differs from composition of the original group, difficult to recover from, less diversity in the end

Founder Effect

A change in population descended from a small number of colonizing


Creates an entirely new population with different adaptations for a different environment, some genotypes not present in new population

  1. Describe the process through which allopatric speciation can produce new species.
    • Geographic barriers can split populations and then natural selection may favor different traits in the environment of each isolated population, resulting in different adaptation
    • Over time, the two populations may become so genetically distinct that they can no longer interbreed creating two new species
    • Happens through geographic isolation and then reproductive isolation
  2. How can sympatric speciation occur if the individuals a population are not geographically isolated?
    • Polyploidy: number of chromosomes increases to 3, 4 or 6 sets instead of two during the division of reproductive cells
    • Once organisms become polyploid, they can’t interbreed with their diploid ancestors
  3. Why is the rate of environmental change a critical factor in determining whether or not a species can successfully adapt?
  • A slowly changing environment gives species more time to adapt to the changes, and makes it way easier to survive
  1. How do a population’s size and genetic diversity influence its ability to adapt to change?
    • Larger genetic variation means a wider variety of phenotypes which means that it's more likely that at least some individuals will be well suited to the new environmental conditions
    • Small populations usually have less genetic variation than larger ones
    • If a beneficial mutation happens, it spreads way faster in a small population than a larger population
  2. How do a species’ range of tolerance for various conditions determine its fundamental niche?
    • If a certain abiotic factor moves further from ideal for a species, it will be more difficult for the species to reproduce and grow
    • Then it will be more difficult for the species to even survive
    • Then the species will die
    • In the fundamental niche, a species survives, grows, and reproduces
  3. Why doesn't species always use their full fundamental niche?
    • Competitors, predators, and disease
  4. What are some of the major differences between niche generalists and niche specialists? Generalists: live in wide variety of areas, or feed on a wide variety of species
    • Specialists: can only live in a certain habitat or feed on a small group of organisms
  5. Scientists think the average lifespan of a species is just 1-10 million years. Why do you think there are such a high rates of speciation and extinction constantly occurring throughout the history of life on Earth?
    • The environment is always changing whether from natural disasters in the past that caused many mass extinctions or now humans
    • Competition between species for favorable conditions
    • Sometimes the environment changes way too rapidly for a species to adapt Survival of the fittest
  6. If extinctions are generally a result of changes in the environment that a species is unable to adapt to, what do you think this indicates about the 5 previous mass extinctions and the 6th one occurring now?
    • The earth is getting more difficult to live on
    • Humans are about to cause a worse mass extinction than the flood with all of the environmentally harmful things they're doing
    • Current species today are the most adapted species on the planet, but species in the past could have amazing traits that we lost from the gene pool forever


Chapter 6 Ecosystem Structure pp. 161-168


- describe species interactions and the roles of keystone species.

  • Explain how the competitive exclusion principle leads to resource partitioning.
  • Describe the four different types of predators and explain why predation is beneficial.
  • Describe different defense mechanisms that prey have evolved in response to predators.
  • Define and give examples of the following symbiotic relationships.

○ Mutualism

○ Commensalism

○ Parasitism

  • Describe the role and characteristics of keystone species.
  • Define and give an example of an ecosystem engineer.


Corridors - strips of natural habitat that connect separated populations

Metapopulations - a group of spatially distinct populations that are connected by occasional movements of individuals between them

Community ecology - the science that studies interactions, which determine the survival of a species in a habitat

Competition - the struggle of individuals to obtain a limiting resource

Competitive exclusion principle - two species competing for the same limiting resource can’t coexist

Resource partitioning - two species divide a resource based on differences in the species’ behavior or morphology

Predation - the use of one species as a resource by another species

True predators - typically kill their prey and consume most of what they kill

Herbivores - consume plants as prey. They typically eat only a small fraction of an individual plant without killing it

Parasites - live on or in the organism (host) that they consume, typically consume only a small fraction of their host and rarely cause death. Pathogens cause disease

Parasitoids - organisms that lay eggs inside of other organisms. When the eggs hatch, the parasitoid larvae slowly consume the host from the inside out, eventually leading to the host’s death

Mutualism - benefits two interacting species by increasing both species’ chance of survival or reproduction

Commensalism - a type of relationship where one species benefits but the other is neither harmed nor helped

Symbiotic relationship - the relationship of two species that live in close association with each other

Keystone species - a species that plays a role in its community that is far more important than its relative abundance may suggest

Predator-mediated competition -

Ecosystem engineers - a species that creates or maintains a habitat for other species

Optional Reading Guide Questions:

  1. Why did Gause’s experiment growing 2 strains of paramecium in the same environment produce a different outcome from when they he grew them separately?
  2. Two species competing for the same limiting resource can’t coexist (competitive exclusion principle)
  3. Competition
  4. Why can’t two species simultaneously share the same realized niche?
  5. One species will perform better and drive the other to extinction
  6. Competition
  7. Why is resource partitioning advantageous for species that would otherwise be competing?
  8. It helps both species survive better either by adapting or finding different times to get their nutrients
  9. Identify each of the following as an example of the competitive exclusion principle, temporal resource partitioning, spatial resource partitioning or morphological resource partitioning:
  • Several species of Warbler Birds hunt insects in the same types of trees, but each feeds in a different part of the tree….spatial resource partitioning
  • When wolves were absent from Yosemite, deer grazed many plant species so heavily that other herbivore species were unable to establish themselves….competitive exclusion principle
  • Many different species of bats use a single watering hole, but each at different times….temporal resource partitioning
  • Different species of butterfly have tongues of varying lengths, each specialized to the shape of the flowers produced by the plants it feeds on...morphological resource partitioning
  • Invasive species that out-compete native species for key resources often drive the native

species to extinction….competitive exclusion principle

  1. Predation

List 2 distinguishing characteristics of each type of predation:

Characteristic 1

Characteristic 2

True predators

Kill prey

Consume most of what they kill


Eat plants without killing them

Eat only a small fraction of the plant


Live on or inside the organism they consume

Eat so little of their host that they rarely cause death


Lay eggs inside other organisms

Consume host from inside out, cause death slowly

  1. Mutualism
  2. Under what conditions would natural selection favor mutualism between two species?
    1. If the cost of helping the other species benefits the other species enough
    2. When a species helps another species to benefit itself
  3. True/false: In a mutualistic relationship, neither species evolves traits suited to helping the other… FALSE
  4. Which of the following are mutualistic: (Lichens) (Viruses) (Coral) (Acacia trees) (African lions)
    1. Acacia trees and ants
    2. Coral reefs and algae iii. Lichens and fungus and alga
  1. Commensalism: True/false: In commensalism, both species benefit FALSE
  2. Keystone Species
    1. How could an ecologist identify a keystone species in any given ecosystem?
      1. If they took this species away, they would see many parts of the ecosystem suffer


  1. Usually exist in low numbers
  1. Why are sea stars and beavers considered to be keystone species in their habitats?
    1. Sea stars prey on mussels that are attached to rocks. This clears spaces so other species can attach to those rocks. Without the predation of sea stars, mussels became numerically dominant while 25 other species declined in abundance
    2. Beavers make up only a small percentage of the biomass in their community, yet they build dams that convert narrow streams into large ponds which creates a new habitat for pond adapted plants and animals. When these ponds overflow into the forest and cause trees to die, it creates habitat for animals that rely on dead trees

Natural Ecosystem Change pp. 168- 173


  • discuss the process of ecological succession.
    • Define ecological succession.
    • Define and diagram primary succession and give examples of when this might occur.
    • Describe the soil formation process in primary succession.
    • Explain why weeds, grasses and wildflowers make good mid-successional plants.
    • Define and diagram secondary succession and give examples of when this might occur.
    • Describe the role pioneer species plays in succession. Give one example.
    • Explain how aquatic succession occurs.
  • explain how latitude, time, area, and distance affect the species richness of a community.
    • Describe the trend of species richness in terms of latitude and time.
    • Define and describe the theory of island biogeography.
    • List three reasons why larger habitats contain more species.
    • Describe the trend between species richness and distance.
    • How does the theory of island biogeography relate to conservation?


Ecological succession - the predictable replacement of one group of species by another group of species over time

Primary succession - occurs on surfaces that are initially devoid of soil such as an abandoned parking lot, newly exposed rock left behind after a glacial retreat, or newly cooled lava

Secondary succession - occurs in areas that have been disturbed but have not lost their soil, follows an event such as a forest fire or hurricane

Pioneer species - species that have an ability to colonize new areas rapidly and grow well in full sunshine

Theory of island biogeography - demonstrates the dual importance of habitat size and distance in determining species richness

Optional Reading Guide Questions:

  1. Primary Succession
    1. Which types of organisms transform bare rock into young soil?
      1. Algae, lichens, or mosses
    2. Where do the mineral and organic components of the new soil come from?
      1. Dead algae, lichens, and mosses that become organic matter and mix with the minerals from eroded rock
    3. What role do mid-successional species such as grasses and wildflowers play in transforming soil?
      1. improve the quality of the soil by increasing its ability to retain nutrients and water
    4. Why do mid-successional species eventually get displaced by late-successional species?
      1. The late successional species can colonize area because of the stronger nutrients in the soil, and they outcompete the mid-successional species
    5. True/false: the number of species present always increases as succession proceeds.
    6. Secondary Succession
    7. How does secondary succession differ from primary succession?
      1. Secondary succession occurs in area that already has soil, in primary succession the soil has to be created from rock
      2. How is the progression of species in secondary succession similar to that of primary succession?
      3. First come the annual weeds
      4. Grasses and wildflowers are the first plants to arrive in both and they colonize the area in great numbers rapidly
  • Then the soil has enough nutrients to grow shrubs iv. Then small trees
  1. Then larger trees
  2. Why has the use of the term climax stage fallen out of favor among scientists?
  3. Because natural disturbances like wind, rain, fire, and outbreaks of insect herbivores are a regular part of most communities, most late-successional phases are not final because they can go back to an earlier stage at any moment
  1. True/false: The Opening Story describes a sequence of primary succession
  2. True/false: In the Opening Story, Goldenrods are late-successional species
  1. Aquatic Succession
    1. On which surfaces does succession occur in the rocky intertidal zone of the Pacific Coast?
      1. On bare rocks that storms turn over
    2. Describe how are lakes can become filled in during aquatic succession:
      1. Over time algae and aquatic plants colonize a lake
      2. The growth of plants and algae and erosion of surrounding rock and soil slowly fill the basin with sediment and organic matter making it increasingly shallow iii. This can take thousands of years, but eventually the lake can fill in
    3. Species Richness, Latitude, Time, Theory of Island Biogeography

Influence of this factor on species richness?

What do you think causes this?


As we move from the equator to the extreme north or south, the numbers of species decline

There are less nutrients in the frozen over freezing cold snow, less producers can root there, can’t support as many consumers


The older a habitat, the greater its species richness is likely to be; younger habitats have

lower species richness

Older communities have had more opportunities for speciation

Habitat Size

Larger habitats usually contain more species

Larger habitats present more

niches; smaller habitats offer fewer resources, easier to find

Distance from other habitats

Islands closer to continents usually have more species than islands further

It’s difficult for species to travel

extremely far distances, many don’t do it

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