Biogeography and Evolution Leith Nye and Rachel Schmidt February 28 2006 Biogeography the study of what organisms live where on earth and why from Humphries and Parenti 1999 A naturalist in Europe Carolus Linnaeus 1707 1778 From the Ark to Ararat Bible AD Young Earth Single creation of perfect species Origin Mt Ararat Turkey where Ark landed Possible remains of Noah s Ark Mt Ararat Linnaeus 1735 Notes variation in form Mountainous island center of origin theory Linnaeus s Mountainous Island Post Flood Buffon the Visionary Georges Buffon 1761 Noted faunistic differences and similarities between regions of similar climate Buffon s Law Georges de Buffon ca 1760 Fossils extinction changes in species climate and geography Map of Artic from Histoire Naturelle Continuing Exploration Humboldt 1805 Plant zonation associations and biomes Alexander von Humboldt Candolle 1820 Coined term endemic Defined ca 20 regions of endemism Disjunctions bipolar and Africa Austraila Augustin Pyrame de Candolle What are patterns of distribution of species seen across the globe Geographical regions have characteristic biotas Similar closely related taxa tend to be closer together than more distantly related groups Similar environments are found in different areas BUT the same species may not be found in all places where they could be Not closely related species in similar environments may appear similar due to convergence How else might we explain this distribution without biogeography principles What distributions would we expect to see WITHOUT macroevolution World s Biomes What broad distribution patterns do we actually see Distinct Faunas across Similar Environments Wallace s Faunal Regions Distinct Floras across Similar Environments Good s Floristic Regions In considering the distribution of organic beings over the face of the globe the first great fact that strikes us is that neither the similarity nor the dissimilarity of the inhabitants of various regions can be wholly accounted for by climatal and other physical conditions Charles Darwin The Origin of Species A reasonable nonevolutionary prediction is that species should occur wherever their habitat is However macroevolution predicts just the opposite there should be many locations where a given species would thrive yet is not found there due to geographical barriers Futuyma D 1998 Evolutionary Biology Third edition Sunderland Mass Sinauer Associates The Origin of Species Evidence Geographical Distribution I and II 1 2 3 Regions with identical climate have different floras and faunas Buffon s Law Geographic barriers closely associated with breaks between taxonomic groups Within a region organisms are often closely related even across environmental gradients and lower taxonomic groups often show narrower distributions than higher 1 Similar Climate Different Taxa Cactaceae in North American deserts Euphorbiaceae in southern African deserts Courtesy of K J Sytsma Geographic Barriers and Distinct Biota More similar marine biota Very different marine biota 3 Closely Related Taxa in Close Proximity Wallace s Line Disjunctions A Bur in Darwin s Saddle Darwin goes to great pains to show how disjunct patterns of species distributions can be explained through climate changes geological changes and dispersal Examples 1 Same alpine species on mountains between and across continents result of cycles of glaciation and migration 2 Similarity of freshwater fish species across continents due to flooding twisters birds salt water tolerance etc 3 Islands biota can be explained by dispersal and previous existence of now submerged island chains Vicariance vs Dispersal similar pattern different process Vicariance Widespread species Continuous continental area Dispersal Erection of ocean barrier Divergence in isolation Disjunct vicariad species Disjunct continental areas Dispersal across ocean barrier Divergence in isolation Species limited to one area Disjunct continental areas Disjunct species Disjunct continental areas Courtesy of K J Sytsma Islands Hawaii vs Madagascar He who admits the doctrine of creation of each separate species will have to admit that a sufficient number of the best adapted plants and animals were not created for oceanic islands for man has unintentionally stocked them far more fully and perfectly than did nature Darwin The Origin of Species Courtesy of K J Sytsma Vicariance Theory Lacking Mechanism Other authors have thus hypothetically bridged over every ocean and united almost every island with some mainland If indeed the arguments used by Forbes are to be trusted it must be admitted that scarcely a single island exists which has not recently been united to some continent This view cuts the Gordian knot of the dispersal of the same species to the most distant points and removes many a difficulty but to the best of my judgement we are not authorized in admitting such enormous geographical changes within the period of existing species Darwin 1859 Courtesy of K J Sytsma Plate Tectonics Enter Alfred Wegener Wegener relied heavily on biogeographical evidence for defending his controversial continental drift theory Glossopteris Permian fern Mesosaurus Freshwater Permian Reptile Cynognathus Triassic land reptile Lystrosaurus Triassic land reptile Courtesy of K J Sytsma Southern Hemisphere Temperate Flora 35 species of trees and shrubs evergreen and deciduous restricted to South America New Zealand Australia Tasmania New Caledonia New Guinea and fossilized in Antarctica Absent from Africa odd continent out Nothofagaceae Courtesy of K J Sytsma Three major patterns of dispersal vicariance modality can be identified 1 Cretaceous dispersal to Madagascar with ensuing distributions from India and or South Africa across Antarctica to South America and Australo E Malesia during the time of the initial radiation of the angiosperms 2 Eocene Oligocene and continuing to the present dispersal to Madagascar and Africa from Laurasia and W Malesia via India pre and post collision with Asia along Lemurian Stepping stones in the western Indian Ocean and 3 continuous and recent long distance dispersal LDD to Madagascar as a function of the prevailing easterly winds and Indian Ocean currents G E Schatz Malagasy Indo australomalesian Phytogeographic Connections Species and Areas History of Ideas Two important scientific advances in the mid 20th century have revolutionized historical biogeography 1 Acceptance of plate tectonics Up until the 1960s most persons considered
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