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Biodiversity
The sum of all lifeforms present in any given location (E.O. Wilson)
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Levels of Analysis
Genes, populations, species, communities, ecosystems, landscapes
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Bacteria
- Produces asexually instead of sexually
- Liven in environments where carbon is not the basis of life (replaced by sulfar in deep thermal vents)
- Do not need air
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How many species are there?
- Estimate 5 to 30 million
- 2 famous estimates
- - Dr. Terry Erwin: entomologist (1982, Coleopterist's Bulletin)
- - Dr. Robert May: theoretical ecologist (1992, Scientific American)
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Erwin's Estimates
- S. American rainforest (Luhea seemanni, tree sp's)
- Method: fogging trees catching dead bugs
- Found 1100 bettles sp's, 160 specialized to canopy Luhea
- 40% of all insects are bettles
- Estimated 400 sp's specialized to L. Seemanii (160 of 40% of 400)
- 2/3 of insects live in canopy, 600 total specialized in 1 tree (400 is 2/3 of 600)
- 50,000 tree sp's in tropical forests, 30 mill. insect sp's in tropics(50,000 trees x 600 insects)
- Insects 75% all known sp's (except 40 mill. sp's of life)
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What's needed to verify Erwin's Estimates?
- Measure tree specificity of insect sp's
- better sampling of canopy & terrestrial insects
- Measure tropical tree diversity thoroughly
- Lose about 300 tropical tree sp's/yr
- Erwin: 300 x 600 = 180,000 arthropods lost/yr; 500/day
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Bob May Mathematics
- Estimate diversity by looking at distributions of sizes of organisms (don't need to know identity of sp's)
- Ecological principles limit the diversity of organisms as they get bigger (ex generation time)
- Plot sp's # on log. scale on y-axis against log of orgnism size
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Genetic studies of Legionella penumophila
- Organims sharing 50% of DNA considered same sp's
- Equivalent to difference btwn fishes & mammals
- Humans & chimps share 99% of DNA
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Any hope for cataloging biodiversity?
- Taxonomists (7 % decline in U.S. & U.K. btwn 1980 & 1990)
- Ageing pop. of systematics (63% over 46 yrs. old; only 8% younger than 35)
- Mismatch btwn location of diversity & location of taxonomists
- 80% scientists in N.AM./Europe, no latin Am. & tropical Africa/Asia
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Sp's distributed on earth?
Depends on spatial scale of analsis & taxonomic group, but some major patterns apparent
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Spatial levels of analysis
- Point Richness (single pt. in space)
- Alpha Diversity (single habitat type/community)
- Beta Diversity (multiple habitats/communities)
- Gamma Diversity (entire regions/collections of ecosystems)
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Point Richness
- Number of sp's at a single pt in space
- Ex. Bird pt count
- Problem: unknown area of habitat
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Alpha Diversity
- Number of sp's in an individual community/ small "homogeneous" area
- Some incorporate measures of abundance
- Problem: detected w/in a single habitat
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Evenness
- When all sp's have relatively same abundance: very even
- All have extremely dissimilar abundances: very uneven
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Alpha Diversity
- Low alpha diversity: few sp's, highly uneven
- High alpha diversity: many sp's, even
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Distribution of biodiversity at the 'alpha diversity level'
- Key correlations w/ increasing sp's richness
- structural complexity of habitat
- primary productivity
- altitude
- latitude
- area
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Structural complexity of habitat
- Positive correlation of sp's richness w/increasing complexity of habitat (in a certain region)
- Ex. Bird Sp's (Grassland << shrubby fields << forests)
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Foilage Height Diversity Profiles
- MacArthur
- Habitats w/ greater complexity support more bird sp's
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Primary Productivity
- Assimilation of energy & production of organic matter by photosynthesis
- Greater primary porduction means more energy is available to support mroe sp's . . . up to a pt.
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Hump-shaped diversity curve
Richness versus productivity
- Produtivity - diversity paradox

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Paradox of Enrichment
- Fertilizing sites w/ high sp's richness causes a decrease in richness
- Salt Marshes, Hot Springs, Seasgrass beds highly productive; have few sp's.
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Altitudinal Diveristy Pattern
- Fewer sp's w/ increasing elevation

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Latitudinal Diversity Gradients
- Richness decreases w/ increasing latitude
- Tropics have more species than temperate areas
- Ex:
- Ants 10 @ 60 degrees N; 2000 @ equator
- Birds: handful at poles; 2500 @ equator
- Exceptions: Marine
- Marine Algae (peak 20-40 N)
- Salamanders & Ichneumonid Wasps (Appalachian Mts)
- Conifers (Boreal Zone)
- Penguins (Antarctica)
- Waterfowl (N. Temperate Zones)
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Islands
- Fewer sp's than comparable area on mainland
- General island patterns
- - Richness Increases w/ (size, topographic (habitat) complexity)
- - Decreases w/ isolation
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Beta Diversity
- Degree of change in sp's composition across habitats
- Cumulative number of sp's detected as move from one habitat to the next
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Species Accumulation Curves
- Effort Curve
- Plot number of sp's found versus measure of effect

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Beta Diversity Influenced By
- Habitat specificity (degree of specialization)
- Thought to be higher specialization in tropics
- - geographic range sizes
- - smaller in tropics (poorly known)
- - altitudinal ranges smaller in tropics
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Gamma Diversity
Overall richness across entire regions or landscapes (regional sp's pool)
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Diversity Measures
- 2 components
- Richness is # of sp's
- Diversity is richness & pattern of abundance
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Measuring S (richness)
- Sp's Accumulation Curve
- Cumulative # of sp's found as a function of effort spent searching
- - Time Spent Searching
- - # of individuals identified
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Chao's Estimator
S* = S obs + (a 2/2b)
- S*: estimated # of sp's
- Sobs: # actually found & identified
- a: # of sp's where we saw only one individual (singleton sp's)
- b: # of sp's where we saw 2 individuals (doubleton sp's)
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Chao's Variance
- VarianceChao = b[{c4/4) + c3 + (c2/2)
- C= a/b
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Confidence Interval
- Approximate a confidence interval w/ 2 times standard deviation
- Explains if our observed S fall w/ in 2 standard deviation of our estimated S*
- Square root of variance is equal to the standard deviation
- 1 S.D. above & below a mean = 64% all possible estimates
- 2 S.D. = 96 %
- Calculate by:
- S.D. = square root variance
- S* = S* +/- 2(S.D.)
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Simpson's Diversity Index
- D = 1/SUMpi2
- Calculate proportion of all individuals represented by each sp's
- pi: fraction of individuals out of the whole sample of organisms that are of a certain sp's
- Steps:
- Square each proportion
- Add them together
- Diveide # into 1
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Shannon- Eaver Index
- H' = -SUM [pi*ln(pi)]
- Calculate fraction of all individuals represented by each sp's
- Take natural log (loge) of each pi value
- Multiply pi times ln(pi) for each sp's
- Sum all those products
- Take the negative to get H'
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Species area relationship
- Space increases in site, # of sp's in space increase
- Bases for wildlife ecology:
- - biogeography theory: bigger islands have more sp's than smaller islands
- - conservation strategies: big reserves will preserve more sp's than small reserves
- - predictions of how habitat loss will affect species richness
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Sp's Area & Power Curve
- S = cAz
- logS = (log c) + z (log a)
- S = # of sp's
- C = constant measuring # of sp's per unit area
- A = area of island
- Z = Constant measuring slope of line relating to S and A
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Use relationship to protect sp's losses
- Inventory plots of various sizes
- construct sp's area graphs
- predict effects of habitat loss
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Area Sensitive Sp's
sp's occuring only in habitats/ islands/ reserves of a certain size or larger
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Incidence Functions
- Best Studied in Vertebrates
- shows the frequency of occurence of a sp's w/ respect to habitat patch area
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Incidence function calculations
- survey many sites for a sp's
- sites need to range in sizes
- need method for ensuring detection of sp's of interest
- generate graph of occupancy vs. size of area surveyed
- look at shapes of incidence functions to determine area sensitivity
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Who's the most vulnerable to fragmentation?
- Wide ranging sp's (mt. lion: food occur sparsley/ hard to catch)
- Naturally rare sp's (ivory-billed woodpecker: old growth swamps & trees)
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Sp's of limited mobility
- immigration btwn patches might be eliminated, therefore reducing persistence
- dung beetle (beetles), amphibians (salamanders), some tropical birds
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Sp's with low fecundity
inability to adjust to different levels of predation in fragments; can't reproduce frequency enough to offset higher predation
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Ground nesters
- if populations of terrestrial predators increase in fragments, ground nesters decline
- ex. racoons
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Sp's vulnerable to human exploitation / persecution
- fargmentation allows easier human access, increase negative encounters (road kill)
- ex. parrots (tree cavities, low pop. densities)
- - breed in small fragments = high chance person locate nests
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Sp's with short life cycles
failure to reproduce in successive yrs. might doom popoulation; longer lifespan increases chances of success
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Sp's dependent on patchy resoruces
patchy resources may not be plentiful in smaller fragments; may occur irregularly in time
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Interior Sp's
some sp's require resource found only deep w/in patches (microclimate conditions, food, etc)
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Why does fragmentation affect soem sp's
- Reduction in total areas of habitat
- Edge effects
- Ecological Traps
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Edge Effects
- Edges are transition zones btwn habitat types (ecotones: boundaries btwn natural communities)
- some predators sp's proliferate in disturbed habitats
- Microclimatic changes alter habitat (more sunlight, drier, more wind exposure)
- Structural changes in habitat (increased veg. density, more weedy sp's, more treefalls)
- Parasites increase in abundance
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Brood Parasitism
- Parasitize the parental care of hosts
- Female find the nests of songbirds & lay their eggs & leave them
- Go find another nest to do same (up to 40 or more)
- Find nest w/ eggs same size or smaller
- Ex: Cowbirds
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Reduce RS of hosts
- Often remove host egg(s) when laying cowbird egg
- Cowbirds eggs hatch first
- Young get most of food
- Sometimes eject host eggs or young
- Some hosts do not recognize that cowbird is not thier own, so don't breed again that yr.
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History of cowbirds
- Native to great plains
- Followed bison (nomadic, lay egg & leave)
- Not a forest sp's, so parasitized grassland sp's
- Grassland sp's adapted to tolerate parasitism and/or recognize cowbird eggs & eject them
- Forest clearing allowed range expansion to east & west
- Continental build up in #'s
- Access to native host sp's not able to compensate for brood parasitism
- Now parasitize over 100 sp's of songbirds
- Max commuting range 7-10 km (Large forest provide habitat for songbirds)
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Corea Area
- Portion of a fragment that is not influenced by edge effects
- Dependent on shape
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Ecological Traps
- Situations where habitat structure attracts individuals, but biotic alterations reduce reproductive success

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Habitat Loss
- Area has been reduced & expect decline in sp's richness to occur becasue of reduction in habitat
- - primary factor causing sp's to become rare & endangered
- Happens for all habitats, but we'll focus on forests
- Examples
- - USA: 1620 - Pilgrims 1st, forest extensive (a lot)
- - Costa Rica: Lost 70% of forests in 45 yrs
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Predictable sequence of forests loss
- Cadiz Township in Wisconsin
- -1831: area covered by forests (farmers colonized area & began to cut trees, forest became distributed as isolated patches)
- -1902: few larger patches were left
- - 1950: dominated by agriculture & only few small isoated patches
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Perforation
- Forman's Categories
- Initial stage of fragmentation
- - clear cuts, developement of homestead, slash & burn

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Dissection
- Forman's Categories
- Creation of linear strip of deforested habitats
- - Creation of roads /powerline corridors

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Fragmentation
- Forman's Categories
- Isolated patches of habitat by removing some forest from landscape

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Shrinkage
- Forman's Categories
- Loss of area from habitat patches

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Attrition
- Forman's Categories
- total loss of patches

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Faunal Relaxation
Loss of sp's through time after isolation
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Super Saturation
- Fragment during spike, has more sp's than expected given its area

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Biological Dynamics of Forest Fragments Project
- Manaus, Brazil
- - Cut trees to isolate several 1, 10, 100 ha fragments
- Found faunal relaxation
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Extinction Debt
- Expected # of sp's losses based on sp' area equation

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Sp's isolation relationships
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Why sp's disappear from fragments
- Sp's area effects: habitat is lost, area declines
- Sp's isolation effects: poor dispersers don't recolonize after extinctions
- Sp's environment effects: changes in abiotic conditions after habitat quality
- Sp's interaction effects: changes in food web organization
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