Ecosystems and the Living Environment

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Chapter 5

• Ecosystems and the Living Environment

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Your Responsibility BY
NEXT CLASS
HINTHINT

• Pages 81-88
• Evolution basics
• Kingdoms of Life
• Biological Communities/Succession
• Pages 92-94
• Predation
• Competition
• Dont ignore the Envirobriefs!!!

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EvolutionHow Populations Change Over Time

• RB Pages 82-84
• Miller Chapter 5

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Whered we all come from?

• The Science Perspective.
• Evolution
• Genetic change in a population of organisms that
  occurs over time.
• Dates back to Aristotle
• Charles Darwin proposed the mechanism that is
  accepted today.

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• Main Idea inherited traits favorable to survival
  in a given environment tend to be preserved, and
  unfavorable ones are eliminated.

Survival of the Fittest Results in ADAPTATION
evolutionary modification that improves chances
of survival reproductive success of the
population in a given environment. Accumulation
of modifications may result in a new species.
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Evolution by Natural Selection

• Darwin proposed his theory in The Origin of
  Species by Means of Natural Selection (1859)

• Main idea
• More favorable genes increase in frequency in
  successive generations, and fewer unfavorable
  genes survive.
• Well accepted in science
• Mechanisms of evolution are still debated.

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Darwins Voyage
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Evolution by Natural Selection

• 4 observations about nature
• 1. Overproduction
• More offspring produced
• than will survive to maturity.
• 2. Variation
• Individuals have unique
  combinations of traits that make them more/less
  fit for their
  environment.

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• 3. Limits on population growth, or struggle for
  survival
• Environment cant support everyone
• competition for resources,
  predation, or disease!!
• 4. Differential reproductive success
• Those individuals with the most fit
  traits for their
  environment are more
  likely to survive, reproduce, and pass
  their
  traits on to the next generation!

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VIDEO How Evolution Works http//www.pbs.org/wgb
h/evolution/library/11/2/e_s_4.html
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Types of Natural Selection
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Directional Selection

• One extreme of a
• specific trait is more
• advantageous than both
• the other extreme and
• the average trait.
• It pays to be different!!
• Examples
• Peppered Moth
• Bacteria that are
  genetically resistant
  to
  some antibiotics.

Video http//www.pbs.org/wgbh/evolution/library/10
/4/l_104_03.html
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Stabilizing Selection

• Tends to eliminate individuals on both ends of
  the genetic spectrum.
• It pays to be average!!
• Occurs when the environment changes little and
  most species are well-adapted.
• Often mistaken for no selection

Example Birth Weight
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Diversifying (Disruptive) Selection
Environmental conditions favor individuals at
both extremes of the genetic spectrum and
eliminate or sharply reduce individuals with
intermediate genes.

• It pays to be extreme!!
• Examples
• Green vs.
  Brown Anole
• Darwins Finches

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Darwins Finches Each finch species is
specialized for a particular lifestyle
(structure of their beaks) An adaptation to
their specific diets seed eaters, cactus eaters,
insect eaters, fruit eaters) and different from
finches on the South American mainland. 14
species of Galapagos finches decended from a
single ancestor- one or a small population of
finches that originally colonized the
Galapagos. ADAPTIVE RADIATION
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NATURAL SELECTION REVIEW..
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Types of Species Evolution
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a. Convergent Evolution

• Two different species who live in the same type
  of habitat evolve to have similar traits.
• Example Sharks and dolphins
• Dolphins are mammals, Sharks are fish.
• So how did they convergently evolve?
• They look the same and act in similar manners
  because they both live in the ocean, so theyll
  need similar traits!

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CONVERGENT EVOLUTION
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Convergent Evolution
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b. Divergent Evolution

• Two populations of the same species who live in
  different places evolve to become different
• Example Birds
• Now we have penguins puffins!!
• So how do they divergently evolve?
• Penguins live where its cold and where theres
  lots of water. Theres more food for them in the
  water, so they evolved to fly underwater.
• Puffins live where its slightly warmer. Theres
  lots of food sources outside of the water, so
  they continued to fly normally.

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Adaptive Radiation Process by which ancestral
species evolve into a number of diff species.
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Divergent Evolution
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Divergent Evolution
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c. Coevolution

• Two species that interact closely
  may become adapted to one another
• Ex a wolf and a rabbit
• How are they related in an ecosystem?
• So how do they co-evolve?
• If the rabbit evolves to be faster, the wolf will
  have to keep up, so it must also evolve to be
  faster.

Why does he want to eat me? I am sooo cute!
He is getting too fast! I have to run faster
to eat!!
If I want to live, I have to run faster!
Yummy. Rabbit!
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Animal/Plant Coevolution
The gracefully curved bill of the Iiwi enables
it to sip nectar from flowers of the lobelia.
The Iiwi bill fits perfectly into the long
tubular lobelia flowers.
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• ACACIA TREE ANTS

• CATIPILLARS PLANTS

• Tree has large hollow thorns that provide a
  protected nesting site for stinging ants. Ants
  attack any animal and clear away vegetation
  surrounding the tree which helps the tree get the
  sunlight it needs.

• Plants may have poisonous
• chemicals that prevent insects from eating them.
  
• Some caterpillars have the ability to resist
  these poisons.
• They can feed on plants that other insects cant
• As the plant adapted by producing poisonous
  chemicals, the caterpillar adapted by resisting
  them.

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Coevolution
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Types of Species Evolution
Lets Play JEOPARDY!!!
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Natural Selection Species Evolution

• THERE IS A BIG DIFFERENCE!!!
• What is it???

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Biological Communities

• Species compete with one another for food, water,
  living space and other resources.
• Vary greatly in size, lack precise boundaries and
  are rarely completely isolated- they interact and
  influence one another.
• There are communities nestled within one another
  like a set of Chinese boxes.

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Rotting Log Community
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Succession

• The gradual change in species that occupy a given
  area.
• As the environment changes, the community living
  in that environment changes as well
• Two types
• Primary Originates from a lifeless habitat (bare
  rock, lava flow etc).
• Takes thousands of years to complete.
• Lichens moss are primary species (first
  organisms in barren env.)
• Rock ? Lichens ? Soil ? Grass? Non-woody Plants
  ? Pine Trees ? Hardwood Trees
• Secondary Occurs where a disturbance eliminates
  most organisms but does not destroy the soil
• Crabgrass is the primary species
• Fire, storms, human activity
• Grass? Non-woody Plants ? Pine Trees ? Hardwood
  Trees

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What Succession is this?
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Succession and Energy Flow.
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ORDER UP ACTIVITY (PG 89-92)

• Get into a group of 2-3 people
• Grab a packet of order up slips
• Start with the SLIP 1 What is a keystone
  species
• Find the answer to that question on another
  slip.
• Write the answer on your sheet.
• Flip up the fold and start the next question.
• Continue the process until done.

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Keystone Species

• Species that are more crucial to the maintenance
  of their ecosystem.
• Species that are vital in determining the nature
  and structure of the entire ecosystem.
• Not the most abundant organisms but exert a
  profound influence on the entire ecosystem b/c
  they often affect the available amount of food,
  water or other resources.

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• 1. Wolves in Yellowstone
• -Wolves taken out by hunting.
• - Population of elk goes up
• - Grass is overgrazed
• - Beavers leave (do not have saplings
• to dam streams and create water holes)
• - Birds do not have nesting/resting sites
  (water)
• 2. Sea Otters in Kelp Beds
• - Otters hunted for pelts so population
  decreases
• - Urchin population increases
• - feed off the kelp roots destroying the kelp
  forest
• - loss of habitat causes a decrease in fish
  populations,
• seal hide out and makes animals more
  vulnerable to shark attack.
• Loss of one organism (keystone species) has a
• ripple effect throughout the entire community!

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Symbiotic Relationships

• Mutualism (/) Both organisms benefit
• Nitrogen Fixing bacteria Legumes
• Protozoa in termite stomach
• E.coli bacteria Humans
• Commensalism (/0)1 benefits one is not affected
• Remora Fish Shark
• Barnicle Whale
• Parasitism (/-) 1 benefits, 1 harmed
• Tapeworm Dog/Cat/Human
• Lamprey Eel Fish

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Predation

• Consumption of one species (prey) by another
  (predator)
• Strategies
• 1. Pursuit- actively pursue prey
• ex) cat mouse
• 2. Ambush- wait in hiding to catch prey item
  moving by
• ex) angler fish other fish
• -Adaptations that protect plants from being eaten
  include
• spines, thorns, tough leaves and protective
  chemicals
• - Strategies that help animals avoid being killed
  and eaten include
• flight, association in groups, camouflage,
  mechanical/chemical defenses
• Evolution of Camouflage http//www.pbs.org/wgbh/e
  volution/library/01/1/quicktime/l_011_03.html
• Warning Coloration Warning to other animals
  that they possess chemical defenses
• What is MIMICRY?

• Poisonous ?
• (coral snake)
• Non-Poisonous
• (King Snake)

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Predation Adaptations continued
Rattle snakes can sense heat through pits in
their heads.
Scorpions can kill prey with their stinger
venom.
Big teeth claws assist catching prey. Horns
help defend prey attack.
Do I need to explain?
Change color throughout the year
to help blend in.
Insect killed by plant poison.
There is a spider in there. Do you see it?
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What is a Niche?

• Niche role of an organism in the ecosystem
• Same as Habitat??
• Does it relate to Habitat??
• What the organism does- its job
• Includes abiotic and biotic factors
• No two species can share exactly
• the same niche!
• If they do..
• they compete for the same resource!
• Species CAN have similar niches
• ex Lizards
• Same except for the size
• of insects they eat

NO!
YES!
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Fundamental v.s. Realized Niche

• Fundamental Theoretical niche
• Realized Organism actually uses the area
  
• Ex) Barnacles in Scotland
• Live on rock surf zone
• Species A Live higher on rocks- exposed to
  air
• Species B Survives in lower zones
• Scientists took out species B and found that
  once it was gone, species A began to grow lower
  on rocks
• therefore the presence of one species could
  limit the niche of another.

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A fundamental niche is the resources an organism
or population is theoretically capable of using
under ideal circumstances. However biological
constraints (competition) restrict organisms to
their realized niche the resources an organism
or population actually uses.
Species cannot coexist in a community if their
niches are identical.
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Fundamental Realized Niche
Theoretical FUNDAMENTAL
Actual REALIZED
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Limiting Factors

• Limiting Factor
• forces that slow the growth of a population
• 2 kinds
• Density DEPENDENT Limiting Factor
• Dependent on population size
• Related to competition and other interactions
• EX) Food supply, predation, living space, water
  availability
• Density INDEPENDENT Limiting Factor
• Affects the same of a population regardless of
  its size
• Climate, human disturbance, natural disaster
  (fire)
• Ex) Hurricane Andrew Katrina
• - destroyed trees and other organisms
• but considered density independent
• because it destroyed organism
• regardless of population

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Limiting Factor Principle
WRITE THIS IF YOU WANT TO

• Limiting Factor Principle too much or too little
  of any abiotic factor can limit or prevent the
  growth of a population.
• Limiting Factors in Terrestrial Biomes
• Temp, water, light, soil
• Too little precipitation (Desert)
• Limiting Factors in Aquatic Biomes
• Temp, sunlight, dissolved oxygen, nutrients,
  salinity
• Deeper water had colder temp, more oxygen, less
  sun

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Limiting Factors
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COMPETITION

• INTER-SPECIFIC
• INTRA-SPECIFIC

• Competition between two DIFFERENT species.
• Cardinals Finches both compete for the same
  bird seed
• Competition between two individuals of the SAME
  species
• A big cardinal a little cardinal fight for the
  same bird seed

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Interspecific Competition
Interspecific Competition The competition that
occurs between two species. Competition
regulates the size of each population and changes
the relative population density over time due to
competition for resources.
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Competitive Exclusion
The extinction of a local population due to
direct competition with another species for
resources. P. caudatum is excluded by P. aurella
over time due to competitive exclusion.
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Species Richness

• Pages 98-100

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Species Richness

• The number of species present in a community
• Ex Tropical Rainforest Coral Reefs VS
  Geographically isolated islands Mountaintops
• Factors that affect species richness
• Abundance of potential ecological niches
• Closeness to margins of adjacent communities
• Geographical isolation
• Dominance of one species over others
• Habitat stress
• Geological history

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Which ecosystem has higher richness? Evenness?
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The species richness map shows historic and
current species richness for 17 species that
experienced range contractions over more than 20
of their historic range. The change map was
created by subtracting the current from the
historic species richness map. The legend shows
the number of species present and the number of
species lost in the change map.
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1. Abundance of Potential Ecological Niches

• A more structurally complex community will have
  more varied food habitat sources, allowing a
  greater of species.
• Ex forest vs. grassland

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2. Near the Margins of Adjacent Communities

• Here, species richness is usually greater as
  compared to the center.
• ECOTONE transitional zone where 2 or more
  communities meet
• Why would species richness be greater here??
• Contains many niches from the ecotone as well as
  many niches from the adjacent communities!
• Change in species composition at the ecotones
  EDGE EFFECT

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Edge effect Ecotone
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3. Geographical Isolation

• Species Richness is inversely related to this.
• Isolated communities tend to be less diverse
  why???
• Difficult to reach successfully colonize the
  area.
• Species may become locally extinct, and it is
  difficult to replace them.
• Isolated areas tend to be small, thus there are
  fewer potential ecological niches.
• Leads to reproductive isolation.evolution of
  characteristics.

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• Notice that isolated populations on small
  islands (upper left) differ quite substantially
  in color, pattern, and tail feather structure and
  length, and bill size, whereas kingfishers on the
  large island (right) have similar
  characteristics. This pattern is typical for
  species of many kinds of organisms that are
  isolated on islands, mountain tops, etc.
  Isolation over periods of time provides
  opportunity for mutations to spread through small
  populations, thus leading to physical and
  physiological diversity

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Geographic Isolation leads to speciation??? HOW
???
Grand Canyon
World Isolation
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4. One species is dominant over others

• This reduces species richness! Why???
• The dominant species out-competes the others,
  crowding them out.
• Evidence James H. Brown, Univ. of NM
• Removed 3 species of dominant kangaroo rats from
  a section of the Chihuahuan desert.
• In all cases, species richness increased (more of
  the submissive, smaller rat species)

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5. Habitat Stress

• Habitat Stress (increases / decreases)
• species richness?
• DECREASES!
• WHY??????

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6. Geological History

• A region that has gone through many climate
  changes will have lower species richness why??
• Extinction often occurs with climate change, so
  fewer species will have been able to re-establish
  themselves.
• So, in terms of geological
• history, name some places...
• With High species richness?
• With Low species richness?

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Species Richness Summary

• Species Richness is great when
• There are ______ potential ecological niches
• Youre ________ adjacent communities
• The community is/is not isolated
• The community is/is not severely stressed
• There is _____ species dominance over others
• Communities have _______ geologic history

MORE
CLOSE TO
LOW
STABLE
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Effects of Species Richness on Ecosystem
Services Community Stability

• The greater the ecosystems species richness
• the greater the ecosystems ability to supply
  ECOSYSTEM SERVICES
• purifying air and water, absorbing CO2, providing
  wildlife habitats, etc.
• the greater the COMMUNITY STABILITY (the ability
  of a community to withstand environmental
  disturbances).
• This is a consequence of community complexity
• Theres more species variety, so the overall
  ecosystem will be better able to cope with
  changes (if one species is diminished, another
  species will flourish in its place)

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The End!

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