Community structure and biodiversity
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Community Structure and Biodiversity. Chapter 46, part 1. Bell Ringer, 9/9. Come in and sit down QUIETLY. You can keep your desks in groups as long as you can do so quietly. What is one question that you wish had been on the test? Write the question and then answer it.

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Community structure and biodiversity

Community Structure and Biodiversity

Chapter 46, part 1


Bell ringer 9 9

Bell Ringer, 9/9

  • Come in and sit down QUIETLY. You can keep your desks in groups as long as you can do so quietly.

  • What is one question that you wish had been on the test? Write the question and then answer it.

  • What are some ways that organisms interact in the environment? (‘I don’t know’ is not an acceptable answer. Brainstorm some ideas!)


Levels of organization

Levels of Organization

  • Biosphere: The earth’s surface; where all life exists

  • Ecosystem: The interactions of all living and non-living things in an area

  • Community: The interactions of all living things in an area

  • Population: The members of a species in an area interacting with one another

  • Organism: One individual living thing


Levels of organization1

Levels of Organization

  • Organ System: Group of organs that interact with each other

  • Organ: Group of tissues interacting with one another

  • Tissue: Group of specialized cells interacting

  • Cell: The basic unit of life


Community structure and biodiversity

Biosphere

Ecosystem

Community

Population

Organism

Organ System

Tissues

Cell


Community structure and biodiversity

Biosphere

Ecosystem

Community

You are here

Population

Organism

Organ System

Organ

Tissues

Cell


Factors that shape community structure

Factors that Shape Community Structure

  • Habitat: The type of place where a species lives

  • Communities have dynamic structures based on:

    • Climate and topography

    • Types and amounts of food and other resources

    • Species’ adaptations

    • Species’ interactions

    • Timing and history of disturbances


Bell ringer 9 10

Bell Ringer, 9/10

  • Come in and find your seat quietly

  • Get out your notes

  • Answer the following question on your bell ringer:

    • Pick ONE factor that shapes community structure and explain how it affects the community.


Factors that shape community structure1

Factors that Shape Community Structure

  • All members of a community have the same “address” but different “professions”

  • Niche: A species’ ecological role; includes conditions, resources, and interactions necessary for survival and reproduction

    • Fundamental niche: The niche that an organism can have

    • Realized niche: The niche that an organism ACTUALLY has


Factors that shape community structure2

Factors that Shape Community Structure

  • Example: Barnacles


Factors that shape community structure3

Factors that Shape Community Structure

  • Ex. Finches


Factors that shape community structure4

Factors that Shape Community Structure

  • Coevolution: When two species in close interaction with one another evolve in response to one another

    • Hummingbirds and flowers

    • Garter snake and rough skinned newt


Factors that shape community structure5

Factors that Shape Community Structure

  • Categories of Species Interactions:

    • Commensalism: Benefits one species and does not affect the other (bacteria in your gut; barnacles on a whale)

    • Mutualism: Benefits both species (ants & acacia tree)

    • Interspecific competition: Harmful to both species

    • Predation: Free-living organism kills and eats another (lion and gazelle)

    • Parasitism: Live in or on host and usually don’t kill it (fleas, ticks, mistle toe, tape worms)


Exit slip 9 9

Exit Slip, 9/9

  • When will your rewritten notes be checked?

  • Compare and contrast predation and parasitism. Give an example of each.


Bell ringer 9 101

Bell Ringer, 9/10

  • Get your Exit Slips (on 2nd lab table)

  • Get your pink paper (on 2nd lab table)

  • On your bell ringer paper, answer the following question:

    • Explain the difference between a fundamental niche and a realized niche. Give an example of each.

    • Pick ONE factor that shapes community structure and explain how it affects the community.


Bell ringer 9 11

Bell Ringer, 9/11

  • Get your FRAYER MODELS from the back and put them behind your Ch. 47 notes in your binder

  • Answer the following questions on your bell ringer:

    • A unicorn can survive in warm or cool temperatures. Their main competition, the magical fairy, thrives in warm temperatures. Based on this information, what is the unicorn’s fundamental niche? Realized niche?


Factors that shape community structure6

Factors that Shape Community Structure

  • Symbiosis: Species that spend most or all of their life cycles in close association

    • Symbiont: A symbiotic species

    • Endosymbiont: A species that lives inside its partner

    • Parasitism, mutualism, and commensalism can all be types of symbiosis

    • http://www.brainpop.com/science/ecologyandbehavior/symbiosis/


Commensalism

Commensalism

  • Relationship in which one species benefits and the other is not affected

    • Cattle egrets and livestock

    • Army ants and birds

    • Stomach bacteria?


Mutualism

Mutualism

  • Interaction in which both species benefit

  • In some mutualisms, neither species can complete its life cycle without the other

    • Yucca plants and moths


Mutualism1

Mutualism

  • Most mutualistic interactions are not life or death

    • Plants have more than one pollinator

    • Nitrogen-fixing bacteria

    • Lichens

  • There is often some conflict between partners

    • Lichens: Algae and fungal symbionts


Mutualism2

Mutualism

  • Some mutualists defend one another

    • Clown fish and sea anenomies

    • Ants and the acica tree


Mutualism3

Mutualism

  • The Theory of Endosymbiosis

    • Mitochondria and chloroplasts were once independent bacteria engulfed by a bigger cell

    • Host relied on ATP produced; symbiont relied on raw materials from the host

    • Eventually, they became incapable of living independently


Mutualism4

Mutualism

  • Evidence for the Theory of Endosymbiosis

    • Amoeba experiment by KwangJeon (1966)

    • Resemblance to bacteria in size and structure

    • Replicates independently of the main cell

    • Internal membranes resemble those of bacteria

      See Ch. 20.4 for more information!


Parasitism

Parasitism

  • Parasites spend all or part of their life living in or on other organisms

    • Steal nutrients from the host

    • Have big impacts on host populations: Disease, weaken host so it is vulnerable to predation or unattractive to potential mates, cause sterility, shift sex ratios of host species, and many more!


Parasitism1

Parasitism

  • Parasites usually don’t kill the host right away

    • Ideally, a host will live long enough to give the parasite time to reproduce

    • The longer the host survives, the more offspring are produced

    • Host usually only dies from the parasite (not secondary effects) when:

      • It is overwhelmed with parasites or

      • A parasite invades a novel host with no defenses against it


Parasitism2

Parasitism

  • Parasites often lead to secondary effects on the host

    • Gradual drain of nutrients leads to the inability to fight off secondary infections


Parasitism3

Parasitism

Mistletoe

Roundworms

Ophiocordycepsunilateralis

Flea

Tapeworm

Lymphatic Filariasis


Bell ringer 9 12

Bell Ringer, 9/12

  • What evidence have scientists found for the Theory of Endosymbiosis?

  • Why is it beneficial to parasites to keep the host alive as long as possible?

  • Why do some scientists believe that commensalism does not really exist in nature?


Fish dating service

Fish Dating Service


Videos

Videos

  • http://www.youtube.com/watch?v=zTGcS7vJqbs

  • Mutualism

    • http://www.youtube.com/watch?v=Xm2qdxVVRm4

  • Ants:

    • http://www.youtube.com/watch?v=UozWJTuhbMQ

    • http://www.youtube.com/watch?v=R3Mt2E1M6dU

  • Parasites:

    • http://www.youtube.com/watch?v=i80DvTmLPeE

    • http://www.youtube.com/watch?v=uvdiYg6ZN-U

    • http://www.youtube.com/watch?v=xDMzubAvzgg


Bell ringer 9 13

Bell Ringer, 9/13

  • Put your homework in the tray

  • On your bell ringer…

    • Choose a parasite that you learned about yesterday and explain its interaction with its host.

    • List the levels of organization.


Virtual lab

Virtual Lab

  • http://www.biologycorner.com/worksheets/virtual_lab_population.html#.UjJ2odJQEud


Bell ringer 9 14

Bell Ringer, 9/14

  • In Friday’s virtual lab, what happened when the two paramecium were grown together? Why?


Competitive interactions

Competitive Interactions

  • Competition among members of the same species is very intense; leads to evolution by natural selection

    • Natural selection: Process of evolution in which individuals of a population vary in the details of a heritable trait and reproduce with varying amounts of success

    • Evolution: Change in a line of descent


Competitive interactions1

Competitive Interactions

  • Interspecific competition is not usually as intense

    • Interference competition: One species actively prevents another from accessing from a resource

    • Exploitative competition: Species don’t interact directly; they reduce the amounts of resources available for the other by using it


Competitive interactions2

Competitive Interactions


Competitive interactions3

Competitive Interactions

  • Any two species differ in their resource requirements

  • Competition is the most fierce when the supply of a shared resource is the main limiting factor for both


Competitive interactions4

Competitive Interactions

  • G. Gause (1930) conducted an experiment involving two species of ciliated protists

    • Both compete for the same prey (bacteria)

    • Separately, their growth curves are almost the same

    • When grown together, one grew slightly faster and outpaced the other, driving it to extinction


Competitive interactions5

Competitive Interactions

P. aurelia

P. caudatum

Population density

Population density

20

4

8

12

16

24

20

4

8

12

16

24

Time (Days)

Time (Days)

Time (Days)


Community structure and biodiversity

P. caudatumand P. aurelia

Population density

4

8

12

16

20

24

Time (Days)


Competitive interactions6

Competitive Interactions

  • This experiment is the basis of the competitive exclusion principal

    • Whenever two species require the same limited resource to survive or reproduce, the better competitor will drive the less competitive to extinction in that habitat

    • Competitors can only coexist if their resource needs are not exactly the same

      • Example: Gause’s second protist experiment


Think about it

Think About It…

  • Can you think of any examples of times this has occurred in nature?

    • If yes, describe the situation.

    • If no, make up a hypothetical situation and explain it.


Competitive interactions7

Competitive Interactions

  • When two competitor species coexist they suppress each other’s population growth

    • Concept shown in experiment by Nelson Hairston

    • Hairston studied two species of salamanders

    • In two plots, he removed one of each type of salamander. In the control plot he left the populations the same

    • In plots with one salamander, populations soared

    • On control plot, populations stayed in check


Competitive interactions8

Competitive Interactions

  • When two species in an ecosystem are similar, they must find a way to coexist or one will be driven to extinction

  • They do this in two main ways:

    • Resource partitioning

    • Character displacement


Competitive interactions9

Competitive Interactions

  • Resource partitioning

    • Subdividing an essential resource

    • Reduces the competitions among species that require it

    • Ex. Plant roots


Competitive interactions10

Competitive Interactions

  • Character displacement

    • Over generations a trait of one species diverges to lower the competition with other species

    • Natural selection favors individuals that differ most from the other species

      • These are the individuals that get to survive and reproduce (the goal of nature)

      • These are the traits that are passed on to future generations


Predator prey interactions

Predator-Prey Interactions

  • Predators: Consumers that get energy and nutrients from prey

  • Prey: Living organisms that predators capture, kill, and eat


Predator prey interactions1

Predator-Prey Interactions

  • The quantity and type of prey species available affects predator types and vice versa

    • The extent of this affect depends on how the predator responds to changes in prey density

    • Prey density: The population of prey in an area


Predator prey interactions2

Predator-Prey Interactions

  • There are three main predator responses to prey density:

    • Type I: Depends solely on prey density

    • Type II: Depends on the predator’s ability to capture, eat, and digests prey

    • Type III: Depends on both prey density and the ability of the predator to capture the prey

    • Knowing the type of predator response helps ecologists predict long-term effects of predation on a prey population


Predatory prey interactions

Predatory-Prey Interactions

  • Type I Response

    • The proportion of prey killed is a constant so the number killed depends solely on density

    • Passive and filter-feeding predators

    • Ex. Spiders, whales, flamingos


Predator prey interactions3

Predator-Prey Interactions

  • Type II Response

    • The number of prey killed depends on the predator’s ability to capture, eat, and digest it

    • When prey density increases, kills rise sharply at first (more prey available)

    • Eventually kill rate slows (more prey than predator can handle)

    • Ex. Wolf and caribou


Predator prey interactions4

Predator-Prey Interactions

  • Type III Response

    • Number of kills increases until prey density exceeds a certain level, then rises rapidly, then levels off

    • Common in three situations:

      • Predator switches among prey, concentrating on the most abundant prey (“prey switching”)

      • Predators need to learn how to effectively catch the prey

      • Number of hiding places for the prey is limited


Predator prey interactions5

Predator-Prey Interactions

  • Sometimes a predator’s lag in response to changes in prey density leads to a cyclic change in the abundance of predators and prey

    • When prey density is low, predators decline

    • Prey is safer and density increases

    • Predators increase

    • Predation leads to a decrease in prey

    • The cycle repeats


Predator prey interactions6

Predator-Prey Interactions

  • Charles Kreb tracked population densities of the Canadian lynx and snowshoe hare in Alaska for 10 years

    • Set up 1 sq. km plots

    • Used fences to keep predators out of some plots

    • Put extra food and fertilizers on some plots


Predator prey interactions7

Predator-Prey Interactions

  • Results

    • Predator-free plots: Hare density doubled

    • Plots with extra food: Hare populations doubled

    • Found that all these precautions delayed the cycle but did not stop it

      • Other predators flew over the fences

      • Some hares starved to death

      • These models are WAY more complicated than high school biology gives them credit for!


Predator prey interactions8

Predator-Prey Interactions

  • If a genetic trait helps a species escape predation, that trait will increase in frequency

  • If a genetic trait helps a predator overcome its prey, that trait will increase in frequency

  • Each development requires a counterdevelopment

  • This creates a “never ending arms race” for evolutionary developments (coevolution)


Prey defense

Prey Defense

  • There are a myriad of prey defenses:

    • Spikesand hard outer parts

    • Camouflage

    • Warning coloration

    • Mimicry

    • Toxins

    • Last minute survival tactics


Prey defense1

Prey Defense

  • Spikes and hard outer parts

    • Make the prey much more difficult to eat

    • Predators abandon prey in pursuit of an easier catch


Prey defense2

Prey Defense

  • Camouflage

    • Body shape, color pattern, behavior, or a combination thereof that makes an individual blend in with its surroundings

    • Predators can’t eat prey that they can’t find


Prey defense3

Prey Defense

  • Warning coloration

    • Flashy patterns and colors that predators learn to recognize as bad tasting or toxic

    • Predators learn to avoid organisms with that coloration


Prey defense4

Prey Defense

  • Mimicry

    • Evolutionary convergence in body form (species come to resemble each other)

    • Batesian mimicry: When one mimic doesn’t have any undesirable characteristics, but looks like an organism that does


Prey defense5

Prey Defense

  • Mimicry

    • Muellerian: When two species with similar appearance both have unpalatable characteristics


Prey defense6

Prey Defense

  • Toxins

    • Some organisms produce chemicals that make them unpalatable or toxic if eaten

      • Plants

    • Some organisms use toxins they get from their prey

      • Sea slugs


Prey defense7

Prey Defense

  • Last minute survival tactics

    • When an animal is cornered, there are many “last minute” defense tactics

    • Playing dead

    • “Puffing up”

    • Spitting venom or unpleasant odors


Adaptive predator response

Adaptive Predator Response

  • Predators must adapt to prey defenses

    • Stealth

    • Camouflage

    • Avoiding repellents

    • Speed


Adaptive predator response1

Adaptive Predator Response

  • Stealth

    • Predator is able to sneak up on prey


Adaptive predator response2

Adaptive Predator Response

  • Camouflage

    • Predators blend in with the surroundings and can’t be seen by prey


Adaptive predator response3

Adaptive Predator Response

  • Avoiding repellants

    • Ability to “dodge” toxins released by prey

  • Speed


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