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How did we get from Linnaean Taxonomy… Bacteria Archaea Archezoans Euglenoids Chrysophytes Green Algae Brown Algae Red algae Slime Molds True Fungi Bryophytes Tracheophytes Protozoans Myxozoans Multicellular Animals
To a tree-like concept of organisms? Multicellular Animals MyxozoansProtozoans Tracheophytes Bryophytes True Fungi Slime Molds Red algae Brown Algae Green Algae Chrysophytes EuglenoidsArchezoans Archaea Bacteria Original Cell Extant Extinct Long Time with Prokaryotes only BYBPOrigin of Life Cyanobacterial Oxygen First Eukaryotes Multicellular AnimalsLand!
com/evolvingthoughts/upload/2007/04/Willi_Hennig2.jpg Emil Hans (Willi) Hennig German entomologist Hennig developed a mechanism (cladistics) to find the pathways of evolution among related organisms. It is based not only on what one sees, but on many kinds of evidence, including molecular sequences. The pathways are determined by virtue of shared derived characteristics (synapomorphies). Rather than putting organisms into Linnean taxonomicboxes, the cladistics process shows the pathway of evolution.
Evidence Categories History - clearer recently, more obscure anciently Fossils - stratigraphic depth, isotope decay, etc. Chemical - metabolic products such as O 2, S s Molecular - DNA sequence alterations, etc. Developmental sequences - onto- phylo- geny Biogeography - Pangea, Gondwana & Laurasia
How do we find the Evolution Pathway? Phylogenetic Systematics Inferences from comparison of extant organisms Characters-Attributes of the organism » Anatomy » Morphology » Development » Physiology » Macromolecule Sequences Polarizing Character States Plesiomorphies-Ancient, shared by descendants Apomorphies-More-recent derivatives » Synapomorphy-Shared among related organisms » Autapomorphy-Found only in one organism Use of outgroup to compare to ingroup
Typical Cladogram Common Ancestor Extant APresent Ancient Extinct Transitional Forms Time A A A This straight line of evolution is called anagenesis (aka: microevolution). Extant B This branching of evolution is called cladogenesis (aka: macroevolution). A is the common ancestor of extant A and extant B
Research/woodfrog.jpg Rana sylvatica Wood Frog r/amphibian/images/northernLeopardFrog.jpg Rana sphenocephala Leopard Frog Rana palustris Pickerel Frog Rana clamitans Green Frog https://www.denix.osd.mil/denix/Public/ Library/NCR/PhotoGallery/NR-Bull- frog.jpg Rana catesbeiana Bull Frog 5 species of frogs found locally What could have made them speciate?
Figure 1. Hypothetical phenology of frog mating behavior in a pond in the north temperate zone. Mating Activity March April May June July Wood frog Leopard frog Pickerel frog Green frog Bull frog Could the size of the pond, availability of tadpole food, etc. be pivotal? Which frog was mating in mid-March? Which frog was mating in early May? When were three species of frog mating? Why do you think Green and Bull frogs mated so much later?
Model of geographic speciation: Time (10,000 years) one species with unrestricted interbreeding Grand Canyon prevents interbreeding erosion begins interbreeding between populations decreases Kaibab Squirrel North Rim Abert Squirrel South Rim
A C A A B are a clade (is monophyletic) Typical Cladogram Common Ancestor Extant AExtant BPresent Ancient Time A A A Extant C A C are a grade (is paraphyletic) A A B is the sister group of C A A B constitute a clade
Typical Cladogram Common Ancestor Extant AExtant CExtant BPresent Ancient Time A A A A Extinct! Extant DExtant E A D A E are a ? clade Common ancestor + A D E are a ? grade The ABC clade may be, say, a genus. The DE clade may be another genus… in the same family The ABCDE clade would be the family
Typical Cladogram Common Ancestor Extant AExtant CExtant DExtant EExtant BPresent Ancient Time A A A A Extinct! A On the other hand… AB are a genus C is a monotypic genus DE are a genus ABC might be one family DE are in another family ABCDE might constitute an order
Multicellular Animals MyxozoansProtozoans Tracheophytes Bryophytes True Fungi Slime Molds Red algaeBrown AlgaeGreen Algae Chrysophytes EuglenoidsArchezoans Archaea Bacteria Original Cell Extant Extinct Living organisms are part of one clade (monophyletic) Eukaryotic organisms are a clade Prokaryotic organisms are a grade (paraphyletic) Protists are polyphyletic (unnatural taxon) Plants are a clade (monophyletic) Animals and Fungi are a clade!
Fig Pg 601 This is the tree-of-life cladogram used by your textbook It varies in some minor ways, mostly additions. It shows uncertainty as a multifurcation.
Bacterial Phyla Rikettsias DesulfovibriosClostrids Rhodopseudomonads Purple Sulfur Myxobacteria Purple nonsulfur Prochlorophytes Green Sulfur Cyanobacteria Spirochetes ActinomycetesMycoplasmas Original Cell Extant Extinct Gram positive Gram negative -Cell Wall +Parasite +µtubule H2OH2O H2SH2S +Chl A +Chl B +bacteriochlorophyll H2SH2S+NAD H2OH2O +NADP +Para- site +gliding motility Each simple line on our tree of life is, in fact, branches with twigs! Each blue hatch mark shows an evolutionary step…mostly biochem!
Fig Pg 577 This is the textbooks version of the Prokaryotic Cladogram It differs mostly by addition of the Archaea.
A dendrogram is not a cladogram
Is this a cladogram?
Patterns of evolution Time Convergent DivergentParallel
A cladogram of marsupials
This is an area cladogram in which the cladogram is stretched over geographic domains. Notice how the marsupials of Australia are a clade (monophyletic). It is thought that this represents a single colonization followed by adaptive radiation (rapid speciation).