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JH Brown 10-8-13 Species, lineages, functions: Why are they most diverse in the tropics? James H. Brown Department of Biology University of New Mexico Modified from Wallace Award Lecture International Biogeography Society 6th Annual Meeting, Miami, Florida, 2013 JH Brown 10-8-13 THE PATTERNS ARE CLEAR • Species richness increases from poles to equator • Very general pattern all major taxa: animals, plants, microbes all major habitats: terrestrial, marine, freshwater • Also applies to: clades human languages and cultures JH Brown 10-8-13 SPECIES: VASCULAR PLANTS Diversity Zones: Species Numbers of Vascular Plants per 10,000 km2 < 20 1 20-200 2 200-500 3 500-1000 4 1000-1500 5 1500-2000 6 7 2000-3000 3000-4000 8 9 4000-5000 > 5000 10 Barthlott, Kier, Kreft, Küper, Rafiqpoor & Mutke 2005 Nees Institute for Biodiversity of Plants University of Bonn, Germany JH Brown 10-8-13 SPECIES: TERRESTRIAL MAMMALS Hawkins et al. (2011) JH Brown 10-8-13 FAMILIES: TERRESTRIAL MAMMALS Hawkins et al. (2011) JH Brown 10-8-13 SPECIES: FRESHWATER FISH http://www.sciencedirect.com/science/article/pii/S1546509805210014 JH Brown 10-8-13 SPECIES: CORAL REEF ANIMALS fish corals snails JH Brown 10-8-13 SPECIES: SEA GRASSES Short et al. (2007) JH Brown 10-8-13 SPECIES: MARINE PHYTOPLANKTON The Darwin Project - http://darwinproject.mit.edu/?page_id=14 JH Brown 10-8-13 THREE MAIN MECHANISMS FOR LDG ARE STILL UNRESOLVED AND CONTROVERSIAL • Geography of diversification and dispersal “Out of the tropics with conservative niches” indirect effects of kinetics? • Resources / productivity “A larger pie can be divided into more pieces” indirect effects of kinetics? • Ecological and evolutionary rates “The Red Queen runs faster when she is hot” direct effects of kinetics JH Brown 10-8-13 RESOURCES / PRODUCTIVITY Key elements: • Net primary productivity (NPP) of terrestrial ecosystems is correlated with latitude (highest in tropical rain forests) • Higher productivity allows coexistence of more individual organisms • More resources and individuals can be divided among more species, with each share enough to resist stochastic extinction JH Brown 10-8-13 Net primary productivity JH Brown 10-8-13 SPECIES: VASCULAR PLANTS Diversity Zones: Species Numbers of Vascular Plants per 10,000 km2 < 20 1 20-200 2 200-500 3 500-1000 4 1000-1500 5 1500-2000 6 7 2000-3000 3000-4000 8 9 4000-5000 > 5000 10 Barthlott, Kier, Kreft, Küper, Rafiqpoor & Mutke 2005 Nees Institute for Biodiversity of Plants University of Bonn, Germany JH Brown 10-8-13 Net primary productivity Primary production (gC m-2yr -1) 1000 500 0 Jennings et al. (2012) from Mélin and Forster JH Brown 10-8-13 SPECIES: CORAL REEF ANIMALS fish corals snails JH Brown 10-8-13 Hubbell (1997) ECOLOGICAL AND EVOLUTIONARY JH Brown 10-8-13 RATES / KINETICS Key elements: • Environmental temperature is correlated with latitude high in tropical rain forests and oceans • Rates of biological processes increase near-exponentially with temperature • High rates of evolution and ecological interactions generate and maintain high diversity in the tropics especially rates of speciation/extinction, Red Queen coevolution, and ecological predation/parasitism/disease interactions JH Brown 10-8-13 TEMPERATURE Global Warming Art http://montessorimuddle.org/2011/09/01/global-warming-art/ KINETICS OF METABOLISM AND ECOLOGY JH Brown 10-8-13 FROM METABOLIC THEORY Pseudomonas flourescens Knies and Kingsolver (2010) Temperature and species diversity: China JH Brown 10-8-13 Slope = -0.87 Wang et al. (2009) SPECIES RICHNESS INCREASES MORE RAPIDLY WITH NPP AND LATITUDE THAN NUMBER OF INDIVIDUALS JH Brown 10-8-13 Currie et al. (2004) Our data: NSF Macrosystems grant for kinetics of biodiversity JH Brown 10-8-13 Our data: NSF Macrosystems grant for kinetics of biodiversity JH Brown 10-8-13 Temperature: higher turnover in warmer environments: trees Slope of species-area relationship (z) JH Brown 10-8-13 Wang et al. 2009 China North America 20oC | 0 oC | 1/kT JH Brown 10-8-13 Hubbell (1997) Our data: NSF Macrosystems grant for JH Brown 10-8-13 kinetics of biodiversity Arctic-alpine conifer forest: Niwot 2031 individuals, 6 species Temperate deciduous forest: Coweeta 1730 individuals, 52 species Tropical rain forest: Barro Colorado Island 4971 Individuals, 263 species A B D JH Brown 10-8-13 Niwot Harvard Barro Colorado Island Log number of species Productivity via species-area relation: JH Brown 10-8-13 small effect S = S0 AZ Log area If Z = 0.25, S increases only 10-fold with 10,000-fold increase in area Productivity via species-abundance JH Brown 10-8-13 distribution: small effect ln (Abundance) productive unproductive Rank JH Brown 10-8-13 WHERE DO WE GO FROM HERE? • Three classes of mechanisms, which are not mutually exclusive: 1) Earth and phylogenetic history includes “niche conservatism” 2) Productivity includes abundance and biomass 3) Kinetics includes ecology and evolution “the Red Queen runs faster when she is hot” • Elements of all of them will be required, but the synthesis cannot be too complex, because the phenomena are so general RATES OF ECOLOGICAL INTERACTIONS INJH Brown 10-8-13 EXPERIMENTS ARE TEMPERATURE DEPENDENT Burnside, Hammond and Brown (submitted) RATES OF ECOLOGICAL INTERACTIONS INJH Brown 10-8-13 EXPERIMENTS ARE TEMPERATURE DEPENDENT Burnside, Hammond and Brown (submitted) JH Brown 10-8-13 INTERACTION RATES IN ECOLOGICAL EXPERIMENTS ARE TEMPERATURE DEPENDENT Burnside, Hammond and Brown (submitted) JH Brown 10-8-13 INTERACTION RATES IN ECOLOGICAL EXPERIMENTS ARE TEMPERATURE DEPENDENT Burnside, Hammond and Brown (submitted) JH Brown 10-8-13 Red Queen or Janzen-Connell effect of enemies via species-abundance distribution ln (Abundance) Find and suppress dominants COLD HOT Increase, colonize, and speciate when rare Rank SPECIATION RATES OF FOSSIL FORAMINIFERA ARE TEMPERATURE DEPENDENT JH Brown 10-8-13 Allen et al. (2006) JH Brown 10-8-13 HUMAN LANGUAGES Data and analysis by Marcus Hamilton JH Brown 10-8-13 MAMMAL SPECIES Data and analysis by Marcus Hamilton Linguistic diversity and mammal species diversity: variation with latitude JH Brown 10-8-13 JH Brown 10-8-13 Linguistic diversity and mammal species diversity: variation with latitude and temperature Data and analysis by Marcus Hamilton