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What is a phylogenetic tree?. And why are they important?. Echinodermata (sister group to chordates). Chondrichthyes (sharks, rays, chimaeras). Cephalaspidomorphi (lampreys). Amphibia (frogs, salamanders). Cephalochordata (lancelets). Actinopterygii (ray-finned fishes).
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What is a phylogenetic tree? And why are they important?
Echinodermata(sister group to chordates) Chondrichthyes(sharks, rays, chimaeras) Cephalaspidomorphi(lampreys) Amphibia(frogs, salamanders) Cephalochordata(lancelets) Actinopterygii(ray-finned fishes) Reptilia(turtles, snakes,crocodiles, birds) Urochordata(tunicates) Actinistia(coelacanths) Myxini(hagfishes) Dipnoi(lungfishes) Mammalia(mammals) Campbell & Reece textbook
Chordates Craniates Vertebrates Gnathostomes Osteichthyans Lobe-fins Tetrapods Amniotes Echinodermata(sister group to chordates) Chondrichthyes(sharks, rays, chimaeras) Cephalaspidomorphi(lampreys) Amphibia(frogs, salamanders) Cephalochordata(lancelets) Actinopterygii(ray-finned fishes) Reptilia(turtles, snakes,crocodiles, birds) Urochordata(tunicates) Actinistia(coelacanths) Myxini(hagfishes) Dipnoi(lungfishes) Mammalia(mammals) Campbell & Reece textbook
Chordates Craniates Vertebrates Gnathostomes Osteichthyans Lobe-fins Tetrapods Amniotes Echinodermata(sister group to chordates) Chondrichthyes(sharks, rays, chimaeras) Cephalaspidomorphi(lampreys) Amphibia(frogs, salamanders) Cephalochordata(lancelets) Actinopterygii(ray-finned fishes) Reptilia(turtles, snakes,crocodiles, birds) Urochordata(tunicates) Actinistia(coelacanths) Myxini(hagfishes) Dipnoi(lungfishes) Mammalia(mammals) Milk Amniotic egg Legs Lobed fins Lungs or lung derivatives Jaws, mineralized skeleton Vertebral column Head Brain Notochord Ancestral deuterostome Campbell & Reece textbook
The BIG message • Trees provide the best available framework for organizing knowledge of biological diversity • …and for thinking clearly about evolution
200 years Charles Darwin Born Feb. 121809 150 years Origin of Species Publ. Nov. 24 1859
The affinities of all the beings of the same class have sometimes be represented by a great tree. I believe this simile largely speaks the truth….the great Tree of Life….covers the earth with ever-branching and beautiful ramifications The Tree of Life Charles Darwin, On the Origin of Species; pages 131-132
Common ancestry models • Pedigree • A depiction of the ancestry relations within populations • Net-like (reticulate) • Phylogeny • A depiction of the ancestry relations between species • Tree-like (divergent)
parents offspring Four plants connected to their parents
past future
Lineages isolated for long enough lose the ability to interbreed • “…sterility of first crosses and of hybrids… is not a special endowment, but is incidental on slowly acquired modifications, more especially in the reproductive systems…”
Representation of phylogenies? A B C A B C A simplified representation The True History
Some terms used to describe a phylogenetic tree Taxon (taxa) Tip Clade Internal branch Internode Node Root