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
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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)
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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
Theory of Island BiogeographyTheory of Island Biogeography
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1.Islands further from
mainland have lower
immigration rates
2.More distant islands have
lower species diversity
Theory of Island BiogeographyTheory of Island Biogeography
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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 &hibians
•• 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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CompetitionCompetition
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Resource CompetitionResource Competition
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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
2. Preemptive competition
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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
2. Preemptive competition
3. Competitive exclusion
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Competitive ExclusionCompetitive Exclusion
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CompetitionCompetition
Any interaction between two or morespecies for a resource that causes a
decrease in the population growth ordistribution of one of the species
1. Resource competition
2. Preemptive competition
3. Competition exploitation
4. Interference competition
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CompetitionCompetition
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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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Predator AdaptationsPredator Adaptations
• Prey detection and recognition
–sensory adaptations
–distinguish prey from non-prey
• Prey capture
–passive vs. active
–individuals vs. cooperative
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Predator AdaptationsPredator Adaptations
• Prey detection and recognition
–sensory adaptations
–distinguish prey from non-prey
• 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
– camouflage, mimics,
– diurnal/nocturnal
• Avoid capture
– flee
– resist
– escape
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Prey AdaptationsPrey Adaptations• Avoid detection
– camouflage, mimics,
– diurnal/nocturnal
• 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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