Phylogenetic - Plant Geography - Lecture Slides | BOTANY 422, Study notes of Geography

Download Phylogenetic - Plant Geography - Lecture Slides | BOTANY 422 and more Study notes Geography in PDF only on Docsity! 1 Species and Areas: History of Ideas How do you choose between dispersalist and vicariance models? 1. Acceptance of plate tectonics Up until the 1960s, most persons considered the earth's crust to be fixed. Finally, in the 1960s the geological evidence was at hand that made continental drift irrefutable. Two important scientific advances in the mid 20th century have revolutionized historical biogeography 2. Development of new phylogenetic methods Willi Hennig (1950) introduced the modern concepts of phylogenetic theory (first published in 1956). Using this methodology, hypotheses of historical lineages of species could be reconstructed. The affinities of all the beings of the same class have sometimes been represented by a great tree . . . As buds give rise by growth to fresh buds, and these if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications. “Phylogenetics” Charles Darwin, 1859 Phylogenetics Building “trees” - showing how “branches” or “clades” are connected to each other Phylogenetics But . . . We only have extant species - the “leaves” ? - and so we must estimate how the “branches” once connected the “leaves” 2 Phylogenetics: Time Thus . . . Phylogenetics is the estimation of the “tree” through “time” knowing only the “leaves” Phylogenetics: Time & Space However, the “leaves” are scattered over “space”. Some areas have related “leaves”, others have unrelated “leaves”. Thus, phylogenetics is compounded by issues of both “time” and “space”. Phylogenetics: Time & Space & Form Additionally, many related “leaves” appear quite divergent in “form”, while other unrelated “leaves” converge in “form”. Thus, phylogenetics is compounded by issues of “time” and “space” and “form”. “Earth and Life Evolve Together” Leon Croizat (1964) Panbiogeography (Space, time, form: the biological synthesis) One of the first articulations of this synthesis is by the founder of “panbiogeography” . . . 5 Phylogenetics Cladistics strives to recognize or classify groups that are monophyletic — includes all descendants of one ancestor vs. polyphyletic groups — with more than one ancestor vs. paraphyletic groups — with one ancestor, but some descendants are not included Phylogenetics The Bryophytes appear here as a paraphyletic group Cladistics strives to recognize or classify groups that are monophyletic — includes all descendants of one ancestor Common ancestor “If philosophy is the devil’s whore, as Martin Luther once quipped, then biogeography and biological systematics are fast becoming Old Nick’s bordello” (Craw, 1988b) Phylogenetics Phylogenetics and historical biogeography are now intimately intertwined . . . But before looking at how cladistics and biogeography were put together in the 1960s and 1970s, we have to look at panbiogeography a decade earlier Panbiogeography Leon Croizat (1894-1982) In his book “Panbiogeography”, attempts to synthesize “space,” “time,” and “form” — used the metaphor “Earth and Life Evolve Together” “An introductory synthesis of phytogeography, zoogeography, and geology” — title page 6 Panbiogeography In his book “Panbiogeography”, attempts to synthesize “space,” “time,” and “form” — used the metaphor “Earth and Life Evolve Together” “An introductory synthesis of phytogeography, zoogeography, and geology” — title page Although now largely dismissed, Panbiogeography is considered the forerunner of modern historical biogeography methods; recent advocates include Robin Craw • Distributions plotted on maps, and connected by lines • Individual / Generalized tracks • Baselines • Main massings • Intersection nodes • No phylogeny! - comparison of different groups (history of “biotas”) Panbiogeography Panbiogeography Individual track — a line that minimizes the distance connecting all localities (minimal spanning tree) Lepechinia hastata Hawaii Panbiogeography Bryan Drew, 422 TA, and Lepechinia expert Croizat’s very first figure of a track (fig. 3) is Lepechinia (Lamiaceae - mints) showing disjuncts with Hawaii and Mascarenes 7 Panbiogeography Baseline — a track orientated in terms of the sea or ocean basins that the track crosses or circumscribes Panbiogeography Baseline — a track orientated in terms of the sea or ocean basins that the track crosses or circumscribes Aegotheles albertisi Mountain owlet Panbiogeography Main massing — a numerical, genetical, or morphological center of diversity for a particular taxon or group of taxa (allows orientation of track) Main massing of Aegotheles (and extinct Megaegotheles), track, and its orientation Panbiogeography Generalized Track — Congruent individual tracks for unrelated groups: indicates ancestral biota 10 Stewartia sinensis Stewartia malacodendron Theaceae - tea family Stewartia pseudocamellia Phylogenetic Biogeography But there are many animals and plants with the same distribution! All explained by separate centers of origins and dispersal events? Cladistic Biogeography One breakthrough in the application of phylogenetics to biogeography - cladistic biogeography - came with the efforts of biogeographers such as Donn Rosen, Gareth Nelson, and Norm Platnick in their interpretation of Croizat! They would interpret such a pattern as the caddis flies in a different way — Vicariance (erection of barrier in once continual biota) explains this particular distribution just as well Cladistic Biogeography Distributional data are insufficient to resolve decisively either dispersal or vicariance as the cause of a particular disjunct distribution pattern ? One breakthrough in the application of phylogenetics to biogeography - cladistic biogeography - came with the efforts of biogeographers such as Donn Rosen, Gareth Nelson, and Norm Platnick in their interpretation of Croizat! Cladistic Biogeography Platnick and Nelson (1978) argued that “one should not worry about its [a particular distribution] cause but whether or not it conforms to a general pattern of relationships shown by other groups of taxa endemic to the areas occupied” Caddis flies Stewartia One breakthrough in the application of phylogenetics to biogeography - cladistic biogeography - came with the efforts of biogeographers such as Donn Rosen, Gareth Nelson, and Norm Platnick in their interpretation of Croizat! 11 Cladistic Biogeography Aside: perhaps these two ideas should be considered ends of a spectrum: Completion of Panama land bridge allowed migration/dispersal of quite unrelated animal and plant taxa into the two Americas . . . Separate biota Dispersal Cladistic Biogeography Aside: perhaps these two ideas should be considered ends of a spectrum: Completion of Panama land bridge allowed migration/dispersal of quite unrelated animal and plant taxa into the two Americas . . . and at the same time provided a vicariance event in dividing a previously single community of marine organisms into separate Caribbean and East Pacific groups Continuous biota Vicariance • 1970s. Cladistic Biogeography (D. E. Rosen, G. Nelson, N. Platnick) • Integration of Plate tectonics + Vicariance (Leon Croizat) + Cladistics (Willi Hennig) Cladistic Biogeography Area cladogram Biogeographic scenario A B C A B C A B C A B C BC ABC • Correspondence between areas of distribution and phylogenetic relationships (Vicariance) Cladistic Biogeography Step 1 — find monophyletic groups (A,B,C) with taxa occurring in 3 or more areas of endemism (1,2,3) 12 Cladistic Biogeography Step 2 — produce taxon cladograms for each group Cladistic Biogeography Step 3 — produce area cladograms by replacing taxon names with areas Cladistic Biogeography Step 4 — find general area cladogram In Croizat’s terminology, general area cladogram = generalized track, but now with cladistic information Cladistic Biogeography Step 4 — find general area cladogram In Croizat’s terminology, general area cladogram = generalized track, but now with cladistic information 15 N/AN/AParsimony analysis of endemicity Phylogeography Event-based methods Cladistic biogeography Ancestral areas Phylogenetic biogeography Panbiogeography Center of origin and dispersal DISPERSAL AND VICARIANCE DISPERSAL TAXON Parsimony analysis of endemicity Phylogeography Event-based methods Cladistic biogeography Ancestral areas Phylogenetic biogeography Panbiogeography Center of origin and dispersal AREA Parsimony Analysis of Endemicity Parsimony analysis of endemicity (PAE) classifies areas or localities by their shared taxa in a parsimony analysis. The data matrix analyzed is different in that areas = taxa and the taxa = characters. First example done on South African biota. Step 1 — identify areas of endemism to be used. By using a grid or quadrat system instead, one can actually deduce areas of endemism. Parsimony Analysis of Endemicity Parsimony analysis of endemicity (PAE) classifies areas or localities by their shared taxa in a parsimony analysis. The data matrix analyzed is different in that areas = taxa and the taxa = characters. First example done on South African biota. Step 2 — construct data matrix; rows = areas (“taxa”), columns = taxa (“characters”); cells contain either 0 - absence or 1 - presence 011100Area H 011100Area G 011100Area F 010000Area E 000010Area D 000010Area C 000011Area B 100011Area A Taxon 6 Taxon 5 Taxon 4 Taxon 3 Taxon 2 Taxon 1 16 Parsimony Analysis of Endemicity Step 3 — parsimony analysis to derive cladogram of areas; bars indicate share derived characters or shared species Many shared species for an area or groups of areas indicates an area of endemism Parsimony Analysis of Endemicity Step 4 — define areas of endemism Note: parsimony analysis done, but no information about organism relationships used Center of origin for Asteraceae in South America (Kare Bremer) — typical biogeographic analysis of single groups Single Taxon Biogeographical Analysis