evolution, biodiversity, and community processes2. production of new species (speciation), and...

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Evolution,Evolution,

Biodiversity, andBiodiversity, and

CommunityCommunity

ProcessesProcesses

La CaLa Cañada High Schoolñada High School

Dr. EDr. E

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BiodiversityBiodiversity

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How do we getHow do we get

Biodiversity?Biodiversity?

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BiodiversityBiodiversity• Biodiversity

– increases with speciation

–decreases with extinction

• Give-and-take between speciationand extinction changes inbiodiversity

• Extinction creates evolutionaryopportunities for adaptive radiationof surviving species

Interpretations of SpeciationInterpretations of Speciation

Two theories:Two theories:

1.1. Gradualist Model (Neo-Gradualist Model (Neo-

Darwinian):Darwinian):

Slow changes in speciesSlow changes in species

overtimeovertime

2.2. Punctuated Equilibrium:Punctuated Equilibrium:

Evolution occurs in spurts ofEvolution occurs in spurts of

relatively rapid changerelatively rapid change

AdaptiveAdaptive

RadiationRadiationEmergence ofEmergence of

numerous speciesnumerous species

from a commonfrom a common

ancestor introducedancestor introduced

to new and diverseto new and diverse

environmentsenvironments

ExampleExample::

HawaiianHawaiian

HoneycreepersHoneycreepers

Convergent EvolutionConvergent Evolution

Species from different evolutionarySpecies from different evolutionary

branches may come to resemble onebranches may come to resemble one

another if they live in very similaranother if they live in very similar

environmentsenvironments

Example:Example:

1. Ostrich (Africa) and Emu (Australia).1. Ostrich (Africa) and Emu (Australia).

2. Sidewinder (Mojave Desert) and2. Sidewinder (Mojave Desert) and

Horned Viper (Middle East Desert) Horned Viper (Middle East Desert)

CoevolutionCoevolution

•• Evolutionary changeEvolutionary change–– One species acts as a selective force on aOne species acts as a selective force on a

second speciessecond species

–– Inducing adaptationsInducing adaptations

–– that act as selective force on the firstthat act as selective force on the firstspeciesspecies

Example: Example:

1.1. Wolf and MooseWolf and Moose

2.2. Acacia ants and Acacia treesAcacia ants and Acacia trees

2.2. Yucca Plants and Yucca mothsYucca Plants and Yucca moths

3.3. LichenLichen

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ExtinctionExtinction

• Extinction of a species occurs when itceases to exist; may follow environmentalchange - if the species does not evolve

• Evolution and extinction are affected by:

– large scale movements of continents

– gradual climate changes due to continentaldrift or orbit changes

– rapid climate changes due to catastrophicevents

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ExtinctionExtinction

•• Background extinctionBackground extinction - species disappear - species disappear

at a low rate as local conditions changeat a low rate as local conditions change

•• Mass extinctionMass extinction - catastrophic, wide- - catastrophic, wide-

spread events --> abrupt increase inspread events --> abrupt increase inextinction rateextinction rate

•• Five mass extinctions in past 500 millionFive mass extinctions in past 500 million

yearsyears

•• Adaptive radiationAdaptive radiation - new species evolve - new species evolve

during recovery period following massduring recovery period following mass

extinctionextinction

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Mass ExtinctionsMass Extinctions

Marine invertebrates50450 mya

Marine invertebrates70380 mya

Marine vertebrates and invertebrates75-95248 mya

Marine vertebrates and invertebrates44213 mya

Dinosaurs, plants (except ferns and

seed bearing plants), marine

vertebrates and invertebrates. Most

mammals, birds, turtles, crocodiles,

lizards, snakes, and amphibians were

unaffected.

8565 mya

(million

years ago)

Species Affected

Percent

Species

Lost

Date of the

Extinction

Event

http://www.geog.ouc.bc.ca/physgeog/contents/9h.html

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1. Diversity is a balance of factors that increase

diversity and factors that decrease diversity

2. Production of new species (speciation), and

influx can increase diversity

3. Competitive exclusion, efficient predators,

catastrophic events (extinction) can decrease

diversity

4. Physical conditions

a. variety of resources

b. Predators

c. environmental variability

Equilibrium Theory of BiodiversityEquilibrium Theory of Biodiversity

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• Richness(number ofspecies)

• Relativeabundance

• How do wedescribe thesedifferences?

Comparison of TwoComparison of Two

CommunitiesCommunities

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BiogeographicalBiogeographical Changes Changes

• Richness

declines from

equator to pole

• Due to:

–Evolutionary

history

–ClimateFig 53.23 Bird species numbers

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• Species-area

curve

• The larger the

geographic

area, the

greater

the number

of species

Geographic (Sample) SizeGeographic (Sample) Size

Fig. 23.25 North American Birds

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Species Richness on IslandsSpecies Richness on Islands

•• Depends on:Depends on:

––Rate of immigration to islandRate of immigration to island

––Rate of extinction on islandRate of extinction on island

•• These in turn depend on:These in turn depend on:

––Island sizeIsland size

––Distance from mainlandDistance from mainland

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How do species move?How do species move?

• Humans (accidental and intended)

• Animals (sticky seeds and scat)

• Wind and ocean currents (+ or -)

• Land bridges

• Stepping stone islands

– affected by climactic changes (glaciation)

– ocean levels

– short-term weather patterns

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What allowed colonization?What allowed colonization?

• Niche opening

• No competition

• Endemics not utilizing

resources

• Accessibility to

colonists

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Theory of Island BiogeographyTheory of Island Biogeography

1. Immigration rate decreases as island

diversity increases

2. Extinction increases as island

diversity increases

3. Species equilibrium on islands is a

balance of immigration and local

extinction

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1.Smaller islands have lower total

populations

2.Probability of extinction

increases with lower population

3.Smaller islands have lower

species diversity


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1.Islands further from

mainland have lower

immigration rates

2.More distant islands have

lower species diversity


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CommunityCommunity

RelationshipsRelationships

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Niche isthe species’ occupation

and its

Habitatlocation of species

(its address)

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NicheNiche

A species’ functional role in its

ecosystem; includes anything affecting

species survival and reproduction

1. Range of tolerance for various physical and

chemical conditions

2. Types of resources used

3. Interactions with living and nonliving

components of ecosystems

4. Role played in flow of energy and matter cycling

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NicheNiche

Realized niche:Realized niche: more restricted more restricted

set of conditions under whichset of conditions under which

the species actually exists due tothe species actually exists due to

interactions with other speciesinteractions with other species

Fundamental niche:Fundamental niche: set of set of

conditions under which aconditions under which a

species might exist in thespecies might exist in the

absence of interactions withabsence of interactions with

other speciesother species

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Types of SpeciesTypes of Species•Generalist

–large niches

–tolerate wide range of environmental variations

–do better during changing environmentalconditions

•Specialist–narrow niches

– more likely to become endangered

– do better under consistent environmentalconditions

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• Depending upon the characteristics of the organism, organismswill follow a biotic potential or carrying capacity typereproductive strategy

The r-strategists1. High biotic potential – reproduce very fast2. Are adapted to live in a variable climate3. Produce many small, quickly maturing offspring = early

reproductive maturity4. “Opportunistic” organismsThe K-strategists1. Adaptations allow them to maintain population values around the

carrying capacity2. They live long lives3. Reproduce late4. Produce few, large, offspring

r and k strategistsr and k strategists

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Types of SpeciesTypes of Species

•• Native speciesNative species normally live and thrive ina particular ecosystem

•• Nonnative speciesNonnative species are introduced - can becalled exotic or alien

•• Indicator speciesIndicator species serve as early warningsof danger to ecosystem- birds &amphibians

•• Keystone speciesKeystone species are considered of mostimportance in maintaining theirecosystem

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Nonnative Nonnative SpeciesSpecies

•• Nonnative plant species are invading theNonnative plant species are invading the

nation's parks at an alarming rate,nation's parks at an alarming rate,

displacing native vegetation anddisplacing native vegetation and

threatening the wildlife that depend onthreatening the wildlife that depend on

themthem

•• At some, such as Sleeping Bear DunesAt some, such as Sleeping Bear Dunes

National Lakeshore in Michigan, as muchNational Lakeshore in Michigan, as much

as 23 percent of the ground is coveredas 23 percent of the ground is covered

with alien species, and the rate ofwith alien species, and the rate of

expansion is increasing dramatically.expansion is increasing dramatically.

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Indicator Indicator SpeciesSpecies

• a species whose status provides

information on the overall condition

of the ecosystem and of other species

in that ecosystem

• reflect the quality and changes in

environmental conditions as well as

aspects of community composition

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Keystone SpeciesKeystone Species• A keystone is the stone at the top of an arch that supports the

other stones and keeps the whole arch from falling

– a species on which the persistence of a large number of other species in

the ecosystem depends.

• If a keystone species is removed from a system

– the species it supported will also disappear

– other dependent species will also disappear

• Examples

– top carnivores that keep prey in check

– large herbivores that shape the habitat in which other species live

– important plants that support particular insect species that are prey for

birds

– bats that disperse the seeds of plants

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SpeciesSpecies

InteractionInteraction

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CompetitionCompetition

Any interaction between two or more

species for a resource that causes a

decrease in the population growth or

distribution of one of the species

1. Resource competition

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Resource CompetitionResource Competition

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2. Preemptive competition

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3. Competitive exclusion

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Competitive ExclusionCompetitive Exclusion

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Any interaction between two or morespecies for a resource that causes a

decrease in the population growth ordistribution of one of the species



3. Competition exploitation

4. Interference competition

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PREDATION

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Predator AdaptationsPredator Adaptations

• Prey detection and recognition

–sensory adaptations

–distinguish prey from non-prey

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• Prey capture

–passive vs. active

–individuals vs. cooperative

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• Prey capture

–passive vs. active

–individuals vs. cooperative

• Eating prey

–teeth, claws etc.

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Prey AdaptationsPrey Adaptations

• Avoid detection

– camouflage, mimics,

– diurnal/nocturnal

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Prey AdaptationsPrey Adaptations

• Avoid detection



• Avoid capture

– flee

– resist

– escape

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Prey AdaptationsPrey Adaptations• Avoid detection



• Avoid capture

– flee

– resist

– escape

• Disrupt handling (prevent being eaten)

– struggle?

– protection, toxins

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HerbivoryHerbivory

Herbivore needs to find most

nutritious

–circumvent plant defenses

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HerbivoryHerbivory

Herbivore needs to find mostnutritious

–circumvent plant defenses

Herbivory strong selective pressureon plants

–structural adaptations for defense

–chemical adaptations for defense

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HerbivoryHerbivory

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HerbivoryHerbivory

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HerbivoryHerbivory

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Symbiosis:Symbiosis:

MutualistsMutualists,,

CommensalistsCommensalists

and Parasitesand Parasites

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• Symbiosis and symbiotic

relationship are two commonly

misused terms

• Translation of symbiosis from the

Greek literally means “living

together”

• Both positive and negative

interactions

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MutualismMutualismDEFINITION:

An interaction between two

individuals of different species

that benefits both partners in this

interaction

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MutualismMutualism

• Increase birth rates

• Decrease death rates

• Increase equilibrium population

densities,

Raise the carrying capacity

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PollinationPollination

• Animals visit flowers to collect nectar

and incidentally carry pollen from one

flower to another

• Animals get food and the plant get a

pollination service

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• Yucca’s onlypollinator is theyucca moth. Henceentirely dependenton it for dispersal.

• Yucca mothcaterpillar’s onlyfood is yucca seeds.

• Yucca moth lives inyucca and receivesshelter from plant.

Yucca and Yucca MothYucca and Yucca Moth

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Lichen (Fungi-Algae)Lichen (Fungi-Algae)

• Symbiotic relationship of algae and

fungae…results in very different

growth formas with and without

symbiont.

• What are the benefits to the fungus?

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Nitrogen FixationNitrogen Fixation

Darkest areas are nuclei, the mid-

tone areas are millions of bacteria

Gram -, ciliate

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Obligatory MutualismObligatory Mutualism

• Obligatory: An organism can't livewithout the mutualism--either cannotsurvive or cannot reproduce.

– the common pollinator systems likebees and flowering plants

–protozoans in the guts of termites

– the alga in the lichen partnership

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Facultative MutualismFacultative Mutualism

• Facultative: This is "take it or leaveit" for one or both partners

• While the organism benefits whenthe mutualism is present, it can stillsurvive and reproduce without it

–ant mutualisms, such as ants protectingplants from predation

–ants tending aphids

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CommensalistsCommensalists

• Benefit from thehost at almost nocost to the host

• Eyelash mite andhumans

• Us and starlings orhouse sparrows

• Sharks and remora

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Parasites and ParasitoidsParasites and Parasitoids

• Parasites: draw resources fromhost without killing the host (atleast in the short term).

• Parasitoids: draw resources fromthe host and kill them swiftly(though not necessarilyconsuming them).

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Parasitic waspsParasitic wasps

• Importantparasites oflarvae.

• In terms ofbiologicalcontrol, howwould this differfrom predation?

ovipositor

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EcologicalEcological

ProcessesProcesses

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Ecological SuccessionEcological Succession

Primary and Secondary SuccessionPrimary and Secondary Succession

gradual & fairly predictable change in species

composition with time

•some species colonize & become more

abundant;

•other species decline or even disappear.

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Ecological SuccessionEcological Succession

Gradual changing environment in

favor of new / different species /

communities

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Primary SuccessionPrimary Succession

•Gradual establishment of biotic

communities in an area where no life

existed before

•No preexisting seed bank

•newly formed islands (i.e. volcanic

origin)

•retreat of a glacier

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PrimaryPrimary

SuccessionSuccession

GlacierGlacier

RetreatRetreat

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Secondary SuccessionSecondary Succession

• Gradual reestablishment of biotic

communities in an area where one was

previously present.

• Preexisting seed bank

•treefall gaps

•"old field succession"

•forest fire

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DisturbanceDisturbanceEvent that disrupts an ecosystem or community;

• Natural disturbance

•tree falls, fires, hurricanes, tornadoes, droughts,

& floods

• Human–caused disturbance

•deforestation, erosion, overgrazing, plowing,

pollution,mining

• Disturbance can initiate primary and/or secondary

succession

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Ecological StabilityEcological Stability

Carrying Capacity – maximum number of

individuals the environment can support

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Ecological Stability - StressEcological Stability - Stress1. Drop in Primary Productivity

2. Increased Nutrient Losses

3. Decline or extinction of indicatorspecies

4. Increased populations of insectpests or disease organisms

5. Decline in Species diversity

6. Presence of Contaminants

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BibliographyBibliography1. Miller 11th Edition

2. http://abandoncorporel.ca/medias/evolution.jpg

3. http://www.ne.jp/asahi/clinic/yfc/fetus.html

4. rob.ossifrage.net/images/

5. http://www.mun.ca/biology/scarr/Five_Kingdoms_Three_Domains.htm

6. http://www.gpc.peachnet.edu/~ccarter/Millerlec5/Millerlec5.PPT

7. http://www.dnr.state.md.us/education/horseshoecrab/lifecycle.html

8. http://www.falcons.co.uk/mefrg/Falco/13/Species.htm

9. http://www.sms.si.edu/irlspec/NamSpecies.htm

10. http://www.falcons.co.uk/mefrg/Falco/13/Species.htm

11. http://www.globalchange.umich.edu/globalchange1/current/lectures/complex_life/complex_life.html

12. http://nsm1.nsm.iup.edu/rwinstea/oparin.shtm

13. http://www.angelfire.com/on2/daviddarling/MillerUreyexp.htm

14. http://exobiology.nasa.gov/ssx/biomod/origin_of_life_slideshow/origin_of_life_slideshow.html

15. http://www.geo.cornell.edu/geology/classes/Geo104/HistoryofEarth.html

16. http://astrobiology.arc.nasa.gov/roadmap/objectives/o2_cellular_components.html

17. http://pubs.usgs.gov/gip/fossils/

18. http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/halfli.html

19. http://www.accessexcellence.org/AE/AEPC/WWC/1995/teach_rad.html

20. http://biology.usgs.gov/s+t/SNT/noframe/pi179.htm

21. http://www.npca.org/magazine/2001/march_april/nonnative_species.asp

22. http://www.bagheera.com/inthewild/spot_spkey.htm

23. Biology, 2003, Prentice Hall

24. http://www.nearctica.com/ecology/habitats/island.htm

25. http://www.valdosta.edu/~grissino/geog4900/lect_1.htm

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