The structure of community ecology Mark Vellend Departments of Botany & Zoology Biodiversity Research Centre University of British Columbia Is community ecology a mess? 1 …with a key difference in how process is treated Population Community Genetics Ecology Patterns we Diversity and Diversity and want to composition of composition of understand alleles/genotypes species Competition Processes to Mutation Predation Niches Neutrality explain Drift Island biogeography Resource-use trade-offs patterns Colonization-competition trade-offs Migration Disturbance Productivity Evolutionary history Selection Etc. But is the difference real or necessary? Population Community Genetics Ecology Patterns we Diversity and Diversity and want to composition of composition of understand alleles/genotypes species Processes to Mutation Speciation explain Drift Drift patterns Migration Dispersal Selection Selection 2 Question on Ecology 101 final exam: What processes influence species composition and diversity? Answer: Question on Evolution 101 final exam: What processes influence genetic variation? Answer: Mutation Drift Migration Selection 3 Processes that influence community composition and diversity Speciation: The creation of new species. Drift: Random changes in the relative frequencies of species. Dispersal: Movement of organisms/propagules among communities. Selection: Deterministic differential survival or reproduction of species. THE LAST 40 The MacArthur school (Marlboro Circle) YEARS OF COMMUNITY Island Biogeography Simple, general, deterministic models Compare equilibrium to data – draw inferences ECOLOGY That’s fraught with pattern-process problems Most of the world is not at (Strong, Simberloff criticize “assembly rules”) equilibrium most of the time SELECTION Lawton’sManipulative “traditional” field experiments community ecology Patch Better “null” models dynamics and for community Experiments often give good disequilibrium assembly studies answers to trivial questions, are system specific and local Neutral theory: Back to history and theDRIFT ultimate null Spatial ecology geographySPECIATION Macroecology model? (Ricklefs’ regional effects) DISPERSAL Better inferential Metabolic theory Niche-neutral Metacommunities tools (community ecology?) reconciliation (ML, Bayes) 4 Conceptual umbrella Key contribution Competition theory Experimental ecology SELECTION Regional & historical effects SPECIATION (+ DISPERSAL) Neutral theory DRIFT Metacommunities DISPERSAL The Structure of Community Ecology Morin (1999) Putman (1993) Community Ecology Community Ecology I: Communities, Ecological communities - definitions Patterns and Processes: and a search for pattern. Competition I, Competition II Population interactions Predation I, Predation II Food webs and connectance. Food Webs Mutualisms Compartments in food webs. Indirect Effects Food web topology. II: Factors Influencing Interactions: Niche theory Temporal Patterns Habitat Selection Guilds and guild structure. Spatial Dynamics Spp composition, community assembly III: Large Scale Phenomena: A question of equilibrium. Causes and Consequences of Diversity Stability. Succession Applied Community Ecology 5 The Structure of Community Ecology Morin (1999) Putman (1993) Community EcologyCommonalitiesCommunity Ecology I: Communities, Ecological communities - definitions Patterns and Processes:Community patternsand a search for pattern. Competition I, Competition II Population interactions Predation I, Predation II Food webs and connectance. Food Webs Space and time Mutualisms Compartments in food webs. Indirect Effects CompetitionFood web topology. II: Factors Influencing Interactions: Niche theory Temporal Patterns Predation Habitat Selection Guilds and guild structure. Spatial Dynamics Food websSpp composition, community assembly III: Large Scale Phenomena: A question of equilibrium. Causes and Consequences of Diversity Stability. Succession Niches Applied Community Ecology Logical difficulties with this organization Community patterns Pattern Space and time Consideration Competition Process Predation Process Food webs Concept/thing Niches Concept 6 The Structure of Population Genetics Hedrick (2000) Hartl & Clark (2007) Genetics of Populations Principles of Pop. Genetics General Background Genetic & Phenotypic Variation The Diversity of Genetic Variation Organization of Genetic Variation Measures of Genetic Variation Random Genetic Drift Selection: An Introduction Mutation & the Neutral Theory Selection: Advanced Topics Darwinian Selection Inbreeding Inbreeding, Pop. Subdivision, Migration Genetic Drift Molecular Population Genetics Mutation Evolutionary Quantitative Genetics Neutral Theory, Coalescence Population Genomics Gene Flow, Population Structure Human Population Genetics Linkage Disequilibrium, Recombination Molecular Genetics and Evolution The Structure of Population Genetics Hedrick (2000) Hartl & Clark (2007) Genetics of PopulationsCommonalitiesPrinciples of Pop. Genetics General BackgroundMeasurementGenetic of diversity& Phenotypic Variation The Diversity of Genetic Variation Organization of Genetic Variation Measures of Genetic Variation MutationRandom Genetic Drift Selection: An Introduction Mutation & the Neutral Theory Selection: Advanced Topics DriftDarwinian Selection Inbreeding Inbreeding, Pop. Subdivision, Migration Genetic Drift MigrationMolecular Population Genetics Mutation Evolutionary Quantitative Genetics Neutral Theory, Coalescence SelectionPopulation Genomics Gene Flow, Population Structure Human Population Genetics Linkage Disequilibrium, Recombination Molecular Genetics and Evolution 7 Logical consistency of this organization Diversity measures Pattern Mutation Process Drift Process Migration Process Selection Process Why the difference? The architects of the modern synthesis were not distracted by data! (Vieulle and Slatkin 2002 ) 8 Ecology is a discipline “whose material study is part of everyday encounters: birds, bees, trees, and rivers”. “It is, however, a mistake to imagine that this familiarity makes ecology and easy pursuit…the very familiarity of ecological objects presents the difficulties”. (Allen & Hoekstra 1992, Toward a Unified Ecology) A Different Structure for Community Ecology Processes Primary patterns (across space & time) •Drift • Speciation • Species diversity • Dispersal • Species composition Abiotic env. • Selection (identity, traits, abundances) Biotic interactions • Competition • Predation •Etc. Emergent patterns • Productivity • Stability • Food web connectance • Whatever you can think of 9 Relating the many to the few Ecological idea/model/theory Processes Island biogeography Dispersal and drift Resource competition Selection (frequency dependent) Metacommunity theory Dispersal, selection, and drift Neutral theory Speciation and drift Assembly rules Dispersal and selection Spatial/temporal heterogeneity Selection (variable in space/time) Food webs Selection (frequency dependent) Species pool theory Speciation Productivity/stress/disturbance Selection (and speciation) The Evolutionary Modern Synthesis (Stebbins 1971, modified by Kutschera & Niklas 1994) Dispersal Drift A (not so) Modern Synthesis for Community Speciation Dispersal Selection Ecology? (Selection) Selection Selection & Drift (Ricklefs & Schluter 1993) 10 Global community Speciation Drift Selection Dispersal Regional community Dispersal Speciation Drift Selection Dispersal Dispersal Local Community (Speciation) Drift Selection Note: Extinction results from drift & selection Teaching Community Ecology Processes Primary patterns (across space & time) •Drift • Speciation • Species diversity • Dispersal • Species composition • Selection (identity, traits, abundances) Advantages (I hope): • Logical coherence Emergent patterns • Allow links among sub-fields • Productivity to be seen more clearly • Stability • Facilitate communication of the conceptual core of the • Food web connectance discipline more clearly • Whatever you can think of 11.