Transcript Slide 1
Biogeography Terrestrial Zoogeographic Regions Published as “an update of Wallace’s zoogeographic regions” Map from Holt et al. (2013) Science Biogeography Diversity Gradients Birds Map from Hawkins et al. (2006) J. Biogeogr. Biogeography Diversity Gradients Mammals Map from Willig et al. (2003) Ann. Rev. Ecol. Evol. Syst. Biogeography Diversity Gradients – Vascular Plants Image from staffwww.fullcoll.edu Biogeography The study of variation in species composition & diversity among geographic locations Painting (1843) of Alexander von Humboldt & plate from his Geography of Plants (1805) from Wikimedia Commons Community Assembly Global community Drift, Selection, Speciation Dispersal Dispersal Regional community Drift, Selection, Speciation Local community A Drift Selection Speciation Redrawn from Vellend & Orrock (2010) Local community B Drift Selection Speciation Dispersal Dispersal Hierarchy of Scales of Diversity Global diversity Regional-scale diversity or Regional species pool or Gamma diversity () Community A Community B Localscale diversity Localscale diversity or or Alpha diversity () Alpha diversity () *Beta diversity () Original concept from Whittaker (1975) *Beta diversity reflects species turnover Indirect Assessment of Local vs. Regional Influences 1 to 1 Proportionate increase; regional processes dominate over local processes Saturation; local processes limit local richness Cain, Bowman & Hacker (2014), Fig. 18.6 Endemism Found nowhere else 1630 endemic plant species on Southeastern Coastal Plain (Sorrie & Weakley 2001 Castanea) Atlantic Coastal Plain E.g., parrot pitcher plant West Gulf Coastal Plain East Gulf Coastal Plain Longleaf pine transition woodlands Longleaf pine bluestem savannas Longleaf pine wiregrass savannas Longleaf-slash pine wiregrass savannas From Jean Huffman, after Platt (1999) South Florida slash pine savannas Subtropical Coastal Plain Continental Drift Cain, Bowman & Hacker (2014), Fig. 18.11; concept generally attributed to Alfred Wegener (1912) Plate Tectonics The mechanism for continental drift Cain, Bowman & Hacker (2014), Fig. 18.10 Main types of boundaries between plates: Mid-ocean ridge Subduction zone Fault Dispersal vs. Vicariance Dispersal spread these organisms across Gondwana ~150 mya, but vicariance separated their fossils across continents Vicariance = continuous geographic range rendered discontinuous by the emergence of a barrier Map from Wikimedia Commons Dispersal vs. Vicariance Molecular phylogenetic evidence suggests that the ratite common ancestor roamed across Gondwana, but populations diverged as continents separated (i.e., vicariance) However, kiwis appear to have originated in Australia, then dispersed to New Zealand Cain, Bowman & Hacker (2014), Fig. 18.12 Explanations for Origins of Regional Diversity Gradients Area, Isolation, Evolutionary History (e.g., Time, Stability) & Productivity Diversification rate = (Speciation rate) – (Extinction rate) Cradle effect = Higher speciation rate Museum effect = Lower extinction rate Cain, Bowman & Hacker (2014), Fig. 18.15 Explanations for Origins of Regional Diversity Gradients Area, Isolation, Evolutionary History (e.g., Time, Stability) & Productivity Cain, Bowman & Hacker (2014), Fig. 18.16 Explanations for Origins of Regional Diversity Gradients Area, Isolation, Evolutionary History (e.g., Time, Stability) & Productivity Cain, Bowman & Hacker (2014), Fig. 18.15 Explanations for Origins of Regional Diversity Gradients Area, Isolation, Evolutionary History (e.g., Time, Stability) & Productivity Map from http://www.iceagenow.com/Ice-Age_Maps.htm Explanations for Origins of Regional Diversity Gradients Area, Isolation, Evolutionary History (e.g., Time, Stability) & Productivity Cain, Bowman & Hacker (2014), Fig. 18.15 Species-Area Relationship Species-area curves from Rosenzweig (1995) Species-Area Relationship Slope changes across scales Figure from Hubbell (2001, pg. 158) Species-Isolation Relationship Data for Bismark Archipelago birds from Diamond (1972) PNAS Island Biogeography Theory The influence of area & isolation on local species richness Cain, Bowman & Hacker (2014), Fig. 18.16; MacArthur & Wilson (1967) The Theory of Island Biogeography