Historical Biogeography - Lecture Slides | BOTANY 422, Study notes of Geography

Download Historical Biogeography - Lecture Slides | BOTANY 422 and more Study notes Geography in PDF only on Docsity! 1 Floristics Historical Biogeography • Historical biogeography is the flipside to ecological biogeography • Most of its practitioners are not geographers but systematists specializing on specific groups of organisms “What lives where and why?” 1. Descriptive — distributions and areas (floristic geography) Three phases of historical biogeography are usually seen: • Historical biogeography is the flipside to ecological biogeography • Most of its practitioners are not geographers but systematists specializing on specific groups of organisms 2. Narrative — using historical (geological and evolutionary) events and ad hoc assumptions as a basis for explaining a given distribution pattern (including dispersal biogeography) “What lives where and why?” Three phases of historical biogeography are usually seen: Historical Biogeography • Historical biogeography is the flipside to ecological biogeography • Most of its practitioners are not geographers but systematists specializing on specific groups of organisms 3. Analytical — comparison of the patterns of relationships of different groups of organisms occupying similar areas to find common biogeographic patterns • vicariance biogeography • cladistic biogeography • phylogenetic biogeography “What lives where and why?” Three phases of historical biogeography are usually seen: Historical Biogeography 2 Floristic Biogeography Basis to the study of floristics is knowledge of the geographic distribution of organisms • Most obvious feature of geographic distributions is that they are limited • No species is completely cosmopolitan, or found worldwide • Most species and genera, and even many families and orders are confined to restricted regions such as a continent Amborella trichopoda is endemic to New Caledonia Floristic Biogeography Basis to the study of floristics is knowledge of the geographic distribution of organisms • Most obvious feature of geographic distributions is that they are limited • No species is completely cosmopolitan, or found worldwide • Most species and genera, and even many families and orders are confined to restricted regions such as a continent Picea glauca is endemic to boreal forest of North America; Picea (spruce genus) is restricted to the North Hemisphere Basis to the study of floristics is knowledge of the geographic distribution of organisms • Most obvious feature of geographic distributions is that they are limited • No species is completely cosmopolitan, or found worldwide • Most species and genera, and even many families and orders are confined to restricted regions such as a continent Gunnera (Gunneraceae) has a wider but still patchy distribution (Hawaiian species shown here) Floristic Biogeography Distribution Patterns Every species (or higher taxa) has a particular distribution that varies in three important features: • range: entire region or area of occurrence Clematis fremontii (Ranunculaceae) is restricted to three midwestern states leatherflower 5 What kinds of distribution patterns are seen? 1 species of Pitcairnia in west Africa Family Bromeliaceae (pineapples) shows continuous distribution throughout much of tropical and subtropical America, endemic to this region, except for peculiar disjunct in West Africa Distribution Patterns • Endemics • Continuous • Disjuncts (discontinuous) What kinds of distribution patterns are seen? • Endemics • Continuous • Disjuncts (discontinuous) Distribution Patterns Family Humiraceae shows same peculiar disjunct in West Africa - why? (not a floristic question) S. amazonica - water dispersed What kinds of distribution patterns are seen? • each occupies a precise area or range first determined by history • actual ranges are limited by ecological or biological barriers Distribution Patterns • Endemics • Continuous • Disjuncts (discontinuous) • all eight taxa described survive and reproduce in accordance to specific environmental requirements Lythrum salicaria - purple loosestrife • for invasive weeds, perhaps the opposite Types of Endemics • Taxonomic (evolutionary) relicts: sole survivors of once diverse taxonomic groups The primitive angiosperm Degeneria belongs to a lineage that was more species-rich as seen in the fossil record Distribution Patterns 6 Types of Endemics • Taxonomic (evolutionary) relicts: sole survivors of once diverse taxonomic groups The gymnosperm Ginkgo biloba (monotypic order) belongs to an ancient fossil lineage going at least to the Mesozoic Era Distribution Patterns Types of Endemics • Taxonomic (evolutionary) relicts: sole survivors of once diverse taxonomic groups The evolution of this lineage is well laid out in the fossil record, but only one species remains extant, all others are extinct Distribution Patterns Types of Endemics • Climatic (biogeographical) relicts: narrowly endemic survivors of once widespread taxa Ginkgo biloba is also now restricted to a small area of China, and the fossil evidence shows that the species was widespread (as the fossil G. adiantoides) in the temperate northern hemisphere as recently as the Pliocene (3 mya) Distribution Patterns Types of Continuous Distributions • Cosmopolitan: distributed all over the globe (or relative term); indifferent to environmental conditions (e.g., Ceratophyllum in water, dandelion on earth) Distribution Patterns 7 Types of Continuous Distributions • Circumboreal: [circumaustral rare!] Rhododendron lapponicum - lapland rosebay (Ericaceae) Distribution Patterns Types of Continuous Distributions • Pantropic: Palmae - palm family Distribution Patterns Types of Disjunct Distributions • Many types! We will get back to many of them as they offer some of the most interesting insights into biogeographical patterns in plants! • Involve interplay between earth history and biological history Distribution Patterns Classification of major distributions of seed plants (Thorne 1972; Stott 1982) Types of Disjunct Distributions • amphi-Atlantic distribution of the Permian reptile Mesosaurus was used by Alfred Wegener as evidence for continental drift; most disagreed, attributed distribution to swimming (long distance dispersal, LDD) Classification of major distributions of seed plants (Thorne 1972; Stott 1982) Distribution Patterns 10 Re-examine the distribution pattern of Nothofagaceae . . . Nothofagaceae Provincialism . . . a very similar distribution pattern is seen with Stylidiaceae . . . Nothofagaceae Stylidiaceae Donatia Provincialism Nothofagaceae Stylidiaceae • Many species of Acaena (Rosaceae) occur in the same areas of Nothofagus and Stylidiaceae • Does this mean that these two taxa and Acaena have a similar history that gives rise to this pattern? . . . and with Acaena (Rosaceae) Provincialism There is sufficient evidence to show that this same pattern of endemic distribution in the temperate southern hemisphere is repeated by many unrelated groups of organisms! Provincialism 11 Allopatric (vicariant) disjunctions of related taxa Sympatric occurrences of unrelated taxa Question to ponder: What do areas of endemism mean? • Why do southern beeches show broad distributions similar to chironomid midges when neither is necessarily dependent on the other? • Is it that both have independently dispersed and become adapted to similar southern hemisphere habitats (ecology!), • or does history of the biotas and areas in which they occur provide a different and perhaps better answer simultaneously addressing all taxa? Areas of Endemism - Shared areas by many unrelated plants, fungi, and animals Provincialism Allopatric (vicariant) disjunctions of related taxa Sympatric occurrences of unrelated taxa Question to ponder: What do areas of endemism mean? • These are questions not answered by floristics but require other information about earth history and history of the organisms • They are answered (or attempted to!) in the narrative and analytical phases of biogeography Areas of Endemism - Shared areas by many unrelated plants, fungi, and animals Provincialism Floristic Systems Provincialism and Floristic Kingdoms • Provincialism was one of the first general features of land plant and animal distributions noted by such famous 19th century phytogeographers as Schouw (1823) and de Candolle (1855) and zoogeographers as Sclater (1858) and Wallace (1876). • As soon as biologists traveled to different continents, they were impressed by the differences in the biotas on the various landmasses. A goal of early biogeographic classifications was to identify these units of different biota and the physical or historical barriers that prevented the exchange of species. The result was a division of the earth into a hierarchy of regions reflecting patterns of faunal and floral similarities. 1. Descriptive Historical Biogeography! — distributions and areas (floristic/faunistic geography) Joakim Frederik Schouw (1789 - 1852) Danish botanist and geographer, student of Humboldt, and later professor of botany at the University of Copenhagen from 1821. Pioneer in plant geography and the relation between plants and climate. Produced first comprehensive textbook on plant geography. First map of botanical geography showing 25 “kingdoms”, derived from the work of Joakim Schouw (and Humboldt), is from Heinrich Berghaus's three-volume Physikalischer Atlas. Provincialism and Floristic Kingdoms Floristic Systems 12 Six Faunal Provinces - Sclater 1858 Provincialism and Faunistic Provinces • Likewise, ornithologists and mammalogists defined faunistic provinces • Philip Lutley Sclater (1829–1913), British ornithologist who described 1067 species and 135 genera of birds, published in 1858 an important paper in which he divided the world into biogeographic regions on the basis of birds Faunistic Systems Six Faunal Provinces - Sclater 1858 Alfred Wallace’s Line (1876) Faunistic Systems Provincialism and Faunistic Provinces • Alfred Wallace later elaborated on the Oriental and Australian provinces in some detail based on mammals and birds — more on this later Floristic Systems Provincialism and Floristic Kingdoms Floristics generally uses the following hierarchical scheme: Region — generic endemism high Province (Domain) — species endemism high District — subspecies endemism only Kingdom (Realm) — distinctive floras; endemic families Good, Ronald, 1947. The Geography of Flowering Plants. Provincialism and Floristic Kingdoms Ronald Good’s floristic system is the most well known with 6 kingdoms. Other later ones include Armen Takhtajan’s in 1978. Floristic Systems