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Published byAmice Alexander Modified over 9 years ago
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Spent 22 Months Collecting Fine Scale Data on the Composition & Abundance of Bat Species in Caatinga & Edaphic Cerrado Biomes of Northeastern Brazil COMMUNITY ECOLOGIST
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Time Consuming Narrow Specificity Insufficient for Addressing Broad Questions Unclear Comparative Context LIMITATIONS
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RANGE MAPS: Wealth of Biogeographic, Ecological, and Evolutionary Information
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BAT RANGE MAPS: Hall for North America Koopman for South America Supplemented by “Others”
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RANGE MAPS: Expert Opinion Metadata Problems Heterogeneous Quality
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GRADIENTS OF RICHNESS AND RANGE SIZE: BATS AND MARSUPIALS IN THE NEW WORLD
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LATITUDINAL GRADIENT OF SPECIES RICHNESS
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CAUSES Competition Population Size Growth Rates Epiphyte Load Harshness Predation Heterogeneity Niche Width Patchiness Host Diversity Mutualism Epidemics
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CAUSES Stability Productivity Heterogeneity Aridity Habitat Number Predictability Rarefaction Area Seasonality Range Size Evolutionary Speed
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LIMITATIONS Qualitative PredictionsQualitative Predictions Non Mutually ExclusiveNon Mutually Exclusive Unspecified FormUnspecified Form No Expected ValuesNo Expected Values
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Hemispheric Patterns
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CLASSICAL APPROACH RICHNESSRICHNESS L A T I T U D E HOHO H A1 H A2 CHANCE
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STOCHASTIC PROCESSES AND NULL MODELS
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SIMULATION NULL MODEL SIMULATION NULL MODEL LATITUDELATITUDE 0 134575322134575322 RICHNESSRICHNESS
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SIMULATION APPROACH Randomly generate N & S termini for a speciesRandomly generate N & S termini for a species Repeat until S = richness of species poolsRepeat until S = richness of species pools Calculate richness at each latitudeCalculate richness at each latitude Repeat 1,000 timesRepeat 1,000 times Calculate mean and variance of richness per latitudeCalculate mean and variance of richness per latitude
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EFFECT OF SPECIES POOL SIZE SIMULATION RESULTS
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1 q p P 0 PROBABALISTIC APPROACH
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BINOMIAL NULL MODEL p + q = 1 ( p + q ) 2 = 1 p 2 + 2 pq + q 2 = 1 2 pq S = Richness at “P”
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1 0 q p P SPECIES RICHNESS GRAPHIC REPRESENTATION 2pqS Domain
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NULL MODEL Predicts Form of RelationPredicts Form of Relation Quantitative PredictionsQuantitative Predictions FalsifiableFalsifiable
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NEW WORLD BATS AND MARSUPIALS
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Chrotopterus auritus
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Neoplatymops mattogrossensis
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BATS Species rich Trophically rich Abundant in tropics
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BATS – ENTIRE CONTINENT
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BATS – TAXON EXTENT
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BATS – 95% OF EXTENT
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Didelphis virginiana
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Marmosa cinerea
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MARSUPIALS Ancient group of mammals Moderate species richness Trophically diverse in past
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MARSUPIALS – ENTIRE CONTINENT
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MARSUPIALS – TAXON EXTENT
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MARSUPIALS – 95% OF EXTENT
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MODEL UTILITY Deviations from the model differ between bats and marsupialsDeviations from the model differ between bats and marsupials Deviations are not related to the area of latitudinal bandsDeviations are not related to the area of latitudinal bands
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RANDOM SUBSETS 20 Ranges20 Ranges 20 o Latitude20 o Latitude 20 Species20 Species
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RANDOM SUBSETS SPECIES RICHNESS 1 0 q p BATS 20 *** r = 0.77 MARSUPIALS 19 *** r = 0.73 P
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ASSESSMENT Although stochastic mechanisms may not be the only factors affecting gradients, they play an appreciable role throughout the distribution of a biota
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MODEL UTILITY Deviations from the model differ between bats and marsupialsDeviations from the model differ between bats and marsupials Deviations are not related to the area of latitudinal bandsDeviations are not related to the area of latitudinal bands
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MULTIFACTORIAL Many FactorsMany Factors Species-Specific LimitsSpecies-Specific Limits Factor-Specific N and S LimitsFactor-Specific N and S Limits
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EXTRAPOLATIONS Disturbance GradientsDisturbance Gradients Productivity GradientsProductivity Gradients Abiotic GradientsAbiotic Gradients
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LATITUDINAL GRADIENT OF SPECIES RANGE SIZE
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RAPOPORT’S RULE RAPOPORT’S RULE
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METHODOLOGICAL BIASES Tropical Species Temperate Species 0o0o
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SIMULATION APPROACH Randomly generate N & S termini for a speciesRandomly generate N & S termini for a species Repeat until S = richness of species poolsRepeat until S = richness of species pools Calculate correlation between latitudinal range size and mid-latitudeCalculate correlation between latitudinal range size and mid-latitude Repeat 1,000 timesRepeat 1,000 times Calculate mean and variance of correlationsCalculate mean and variance of correlations
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SOUTH AMERICANORTH AMERICA LATITUDINAL RANGE 0 150 100 50 MID-LATITUDE -70 -50 -30 -10 10 30 50 70 BATS
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SOUTH AMERICANORTH AMERICA LATITUDINAL RANGE 0 150 100 50 MID-LATITUDE -70 -50 -30 -10 10 30 50 70 MARSUPIALS
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BATS 0 100 200 FREQUENCY -0.56 -0.53 -0.49 -0.45 -0.42 -0.38 -0.35 -0.31 CORRELATION COEFFICIENT MARSUPIALS -0.63 -0.56 -0.49 -0.42 -0.35 -0.29 -0.22 -0.15 0 100 200 MID-LATITUDE RESULTS Less Negative Less Negative
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LATITUDE RANGE SIZE MID-LATITUDE RESULTS Rapoport’s Rule Empirical Pattern Stochastic Pattern
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Comparisons of Gradients of Diversity at Two Scales: Communities Versus Regional Species Pools
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SCALE Regional Patterns Local Patterns
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LATITUDINAL GRADIENTS OF COMMUNITY ORGANIZATION
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DESIGN Geographical Constraints (50 km)Geographical Constraints (50 km) Ecological Constraints (biome)Ecological Constraints (biome) Sampling Constraints (asymptote)Sampling Constraints (asymptote) Temporally Constrained (1-5 yr)Temporally Constrained (1-5 yr)
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32 Sites Temperate Subtropical Tropical Subtropical Temperate
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DIVERSE HABITATS Riparian Temperate Forest (1) Desert (4) Montane Tropical Forest (6) Wet Tropical Forest (13) Dry Tropical Forest (2) Tropical Woodland-Savanna (1) Wet Semi-Tropical Forest (4) Dry Semi-Tropical Forest (1)
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FAUNAL POOL - SPECIFIC DATA Number of species whose geographic range overlaps a communityNumber of species whose geographic range overlaps a community Identities of species whose range overlaps a communityIdentities of species whose range overlaps a community
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COMMUNITY - SPECIFIC DATA Species identities & abundances in each communitySpecies identities & abundances in each community Indexes of diversity that are sensitive to richness (3), evenness (4), dominance (3), diversity (4)Indexes of diversity that are sensitive to richness (3), evenness (4), dominance (3), diversity (4)
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BIODIVERSITY INDICIES RICHNESS Community Richness Margalef Index Menhinick Index EVENNESS Shannon Index PIE Index Camargo’s Index Shoener’s Index DIVERSITY Camargo Index Log Series Alpha Brillouin Index Shannon Index DOMINANCE Simpson’s Index Berger-Parker Index McIntosh Index
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3 -3 3 0 0 FACTOR 1 FACTOR 2 Tropical Subtropical Temperate Evenness Dominance Diversity Richness Factor Analysis CE O BP PIE SI MD SHD B CD A MAR R SHE MER
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Latitudinal Gradients Richness Evenness B 1 = 0.0002; r 2 < 0.01; P = 0.999 B 1 = -0.055; r 2 = 0.37; P < 0.001
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REGIONAL & LOCAL GRADIENTS Latitude Richness RegionalLocal 12O 90 60 90 1020 3040
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LATITUDINAL GRADIENTS
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