Biogeography and EvolutionBiogeographyA naturalist in Europe…From the Ark to AraratBuffon the VisionaryContinuing ExplorationPowerPoint PresentationSlide 8Slide 9Slide 10Distinct Faunas across Similar EnvironmentsDistinct Floras across Similar EnvironmentsSlide 13The Origin of Species1. Similar Climate, Different TaxaSlide 16Slide 17Disjunctions: A Bur in Darwin’s SaddleSlide 19Islands- Hawaii vs. MadagascarVicariance Theory Lacking MechanismPlate Tectonics…Enter Alfred WegenerSlide 23Slide 24Slide 25What is the ID/creationist response to biogeography?Slide 27Slide 28Slide 29Slide 30Biogeography and EvolutionLeith Nye and Rachel SchmidtFebruary 28, 2006Biogeography“ 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 AraratBible (AD): Young EarthSingle creation of perfect speciesOrigin: Mt. Ararat, Turkey where Ark landed Linnaeus (1735):Notes variation in formMountainous island center of origin theoryPossible remains of Noah’s Ark, Mt. AraratLinnaeus’s Mountainous Island Post FloodBuffon the VisionaryGeorges Buffon (1761)Noted faunistic differences and similarities between regions of similar climate (“Buffon’s Law”)Fossils, extinction, changes in species, climate and geographyMap of Artic from Histoire NaturelleGeorges de Buffon ca. 1760Continuing ExplorationHumboldt (1805)Plant zonation, associations and biomesCandolle (1820)Coined term ‘endemic’Defined ca. 20 regions of endemismDisjunctions: bipolar and Africa-AustrailaAugustin Pyrame de Candolle Alexander von HumboldtGeographical 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.What are patterns of distribution of species seen across the globe?How else might we explain this distribution without biogeography principles??What distributions would we expect to see WITHOUT macroevolution??World’s BiomesWhat broad distribution patterns do we actually see?Distinct Faunas across Similar EnvironmentsWallace’s Faunal RegionsDistinct Floras across Similar EnvironmentsGood’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 SpeciesA 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 AssociatesThe Origin of SpeciesEvidence: Geographical Distribution I and II1. Regions with identical climate have different floras and faunas (Buffon’s Law).2. Geographic barriers closely associated with breaks between taxonomic groups.3. 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 TaxaCactaceae in North American desertsCourtesy of K.J. SytsmaEuphorbiaceae in southern African desertsGeographic Barriers and Distinct BiotaVery different marine biotaMore similar marine biota3. Closely Related Taxa in Close ProximityWallace’s LineDisjunctions: A Bur in Darwin’s SaddleDarwin 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. Dispersalsimilar pattern, different processDisjunct (vicariad) speciesDisjunct continental areasDisjunct speciesDisjunct continental areasSpecies limited to one areaDisjunct continental areasDispersal across ocean barrierDivergence inisolationWidespread speciesContinuous continental areaErection of ocean barrierDivergence inisolationVicarianceDispersalCourtesy of K.J. SytsmaIslands- 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. SytsmaVicariance 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, 1859Courtesy of K.J. SytsmaPlate Tectonics…Enter Alfred WegenerWegener relied heavily on biogeographical evidence for defending his controversial continental drift theory Glossopteris Permian – “fern”Mesosaurus – Freshwater Permian ReptileCynognathus – Triassic land reptileLystrosaurus – Triassic land reptileCourtesy of K.J. SytsmaSouthern Hemisphere Temperate Flora35 species of trees and shrubs, evergreen and deciduous, restricted to SouthAmerica, New Zealand, Australia, Tasmania, New Caledonia, New Guinea,and fossilized in AntarcticaNothofagaceae????Absent from Africa! — “odd continent out”Courtesy of K.J. SytsmaThree major patterns of dispersal/vicariance modality can be identified: 1) Cretaceous dispersal to Madagascar with ensuing distributions from India (and/or South
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