Download - Ecology slides
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 1/43
Bio 356 announcements
Lab meets Wednesday at the UnionBay Natural Area
Field class 7 due Wednesday
Field class 8 due MONDAY at 5 pmin Kincaid 516
Office hours: Monday 9-10 and 1-3in Kincaid 516
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 2/43
What are the biodiversity consequences of habitat loss?
Thomson et al. 2003
Area A
If half of a habitat is lost or transformed, what fraction ofthe species are expected to go extinct?•Half•More than half•Less than half
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 3/43
Biology 356: Lecture #11
Spatial Ecology
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 4/43
Dec4• Introduction to spatial ecology
• Landscape fragmentation consequences
• Island biogeography
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 5/43
Levels of ecological study
IndividualsPopulations
Communities
Ecosystems
Landscapes
Physiological EcologyPopulation Ecology
Species InteractionsBiodiversity
Community EcologyEcosystem Ecology
Spatial Ecology
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 6/43
• A landscape is a heterogeneous area consistingof distinctive patches.
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 7/43
• A landscape is a heterogeneous area consistingof distinctive patches.• A patch is a contiguous area of a defined habitat.
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 8/43
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 9/43
• A landscape is a heterogeneous area consistingof distinctive patches.• A patch is a contiguous area of a defined habitat.• The matrix is the area between patches.• A corridor is a strip of habitat connecting twopatches.
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 10/43
• A landscape is a heterogeneous area consistingof distinctive patches.• A patch is a contiguous area of a defined habitat.• The matrix is the area between patches.• A corridor is a strip of habitat connecting twopatches.
•Edge : border between two contrasting habitats
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 11/43
Patch shape: Edge (perimeter) depends on rulerlength and fractal geometry
Relatively long ruler (scale) generates relatively shortedge
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 12/43
Patch shape: Edge (perimeter) depends on rulerlength and fractal geometry
Relatively short ruler (scale) generates relatively longedge
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 13/43
• Patch shape: S =
Patch shape: Shape depends on perimeter relative toarea
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 14/43
Patch shape
S =
S = Patch shapeP = Patch perimeter
A = Patch area
Which habitat has thegreater value of S?
a)
b)
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 15/43
Patch shape
S =
S = Patch shapeP = Patch perimeter
A = Patch area
Which habitat has thegreater value of S?
a)
b)
Patch shape is the ratio of patch perimeter to theperimeter of a circle with an area equal to patch area.
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 16/43
Lab preview
Record species composition of invertebrates under
each plywood“
island”
at UBNA
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 17/43
Lab preview
Define: patch, matrix, area, perimeter (edge), shape,
corridors
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 18/43
Lab preview
How does plywood“
island”
area affect speciesrichness?Does the density of a given species change with area?
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 19/43
• A landscape is a heterogeneous area composedof ecosystems that form distinctive patches.
• Landscape structure includes the area, shape,composition, and position of patches in a
landscape.
• Landscape structure influences the flow ofenergy, materials, and species across a landscape.
Introduction to spatial ecology: conclusions
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 20/43
Dec4• Introduction to spatial ecology
• Landscape fragmentation consequences
• Island biogeography
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 21/43
How do abundance and diversity change with area?
Thomson et al. 2003
Area A
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 22/43
Species abundance increases with area
# butterflies(individuals)
d d l h
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 23/43
But species density declines with area
Patch area (m 2)
butterfly density(individuals / m 2)
# butterflies(individuals)
Low density ina small area =too fewindividuals topersist
S i i h i i h
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 24/43
Species richness increases with area
# of birdspecies
Species-arearelationships are log-log plots
logS = logc + b logA
b~ 0.25-0.4
S i i h i i h
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 25/43
Species richness increases with area
# of birdspecies
On linear axes, fewerspecies are addedwith each increment of
areaS = c A b
b~ 0.25-0.4
S i i h i i h
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 26/43
Species richness increases with area
# of birdspecies If half of a habitat is
lost or transformed,
what fraction of thespecies are expectedto go extinct?•Half
•More than half•Less than half
L d f i l i
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 27/43
• Species richness increases with patch area,while species density declines.
• Human activity has fragmented habitatsworldwide. For b=0.25, loss of 50% of area predicts16% extinction. For b=0.4, loss of 50% of area
predicts 24% extinction.
Landscape fragmentation: conclusions
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 28/43
Dec4• Introduction to spatial ecology
• Landscape fragmentation consequences
• Island biogeography
Wh d i i h i ith ?
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 29/43
Why does species richness increase with area?
Potential mechanisms:• Species coexist better on large islands, wheredensities are lower.
• Island size correlates with heterogeneity; largerislands support species with different habitatrequirements.
• Island biogeography: Island size and proximityinfluence colonization and extinction rates
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 30/43
Eq ilib i th f i l d bi g g h
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 31/43
Immigration rate(species / time)
Equilibrium theory of island biogeography
# species present
When few species are present, each immigrant islikely to represent a new species; when manyspecies are present, immigrants are less likely torepresent new species.
Equilibrium theory of island biogeography
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 32/43
Equilibrium theory of island biogeography
# species present
When many species are present:• there is a larger pool of potential extinctions• the population size of each species mustdecrease, increasing the likelihood of extinction• competitive interactions are more likely
Extinction rate(species / time)
Equilibrium theory of island biogeography
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 33/43
Equilibrium theory of island biogeography
# species present
Extinction rate(species / time)
Immigration rate(species / time)
Change in species richness =rate of immigration - rate of extinction
Dynamic equilibrium of species richness whenimmigration rate = extinction rate
Equilibrium theory of island biogeography
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 34/43
Equilibrium theory of island biogeography
near
far
# species present
Immigration rate(species / time)
Proximity to other islands increases immigration rate.
Equilibrium theory of island biogeography
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 35/43
Extinction rate(species / time)
small
large
Equilibrium theory of island biogeography
# species present
Extinction rate decreases with island size.
Equilibrium theory of island biogeography
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 36/43
small
large
small, far
large, farsmall, near
large, near
Equilibrium theory of island biogeography
near
far
# species present
Immigration rate(species / time)
Extinction rate(species / time)
Species turnover
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 37/43
Species turnover
Dynamic equilibrium species richness doesnot always have the same speciescomposition
Turnover = Dis-similarity in speciescomposition
Experimental work on island biogeography
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 38/43
Experimental work on island biogeography
Simberloff and Wilson
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 39/43
Experimental work on island biogeography
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 40/43
Simberloff and Wilson
• Experimental islands fumigated
Experimental work on island biogeography
Experimental work on island biogeography
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 41/43
Simberloff and Wilson
Time (days)
# speciespresent
Near
Far
Proximity to other islandsincreased immigration rate.
Experimental work on island biogeography
Composition: species arrive and go extinct
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 42/43
Composition: species arrive and go extinct
Species richness: 20 2 14 17
Island biogeography: conclusions
8/11/2019 Ecology slides
http://slidepdf.com/reader/full/ecology-slides 43/43
• Island biogeography theory predicts that species richnessis a dynamic balance of immigration and extinction rates.Immigration rate depends upon proximity to otherislands, and extinction rate depends upon island size.
• Species composition on islands is expected to changeover time, even if species richness is at a dynamicequilibrium. Species turnover is also likely in space – islandswith similar species richness can have different composition.
Island biogeography: conclusions