Tree representations Identical trees can be drawn in many different ways often

Tree representations identical trees can be drawn in

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Tree representations: Identical trees can be drawn in many different ways, often for esthetic reasons, while preserving the topology. A B C D slanted A B C D rectangular A B C D circular A B C D rectangular (horizontal) How to interpret phylogenetic trees
A B C D E C B A D E Rotating around any node leaves a phylogeny unchanged How to interpret phylogenetic trees
unresolved star tree partially resolved fully resolved or bifurcating polytomy Three trees showing varying degrees of resolution . An internal node with more than two immediate descendants is called a polytomy ’. From Page & Holmes (1998) pectinate symmetrical Tree shape How to interpret phylogenetic trees
How to interpret phylogenetic trees A B C D Cladograms depict relative relationships and recency of common ancestry only; branch lengths have no units or values A B C D Axis has no units Axis has no units
Monophyletic group (called a “ clade ”) Single origin The given set of taxa forms a group that contains their most recent common ancestor and all of its descendants A B C D E commo n ancesto r Terms used for Phylogenetic Groups A, B, C, D, & E comprise a clade
Platyrrhini (monkeys) Homo (human) Pan (chimp) Gorilla (gorilla) Pongo (orangutan) Hylobatidae (gibbons) Cercopithecidae (monkeys) NEW WORLD OLD WORLD Hominidae Is the group Hominidae monophyletic? Terms used for Phylogenetic Groups
Paraphyletic group (called a “ grade ”) Single origin The given set of taxa forms a group that contains their most recent common ancestor and some but not all of its descendants A B C D E commo n ancesto r Terms used for Phylogenetic Groups Here, B, C, D, & E form a paraphyletic group Why?
Platyrrhini (monkeys) Homo (human) Pan (chimp) Gorilla (gorilla) Pongo (orangutan) Hylobatidae (gibbons) Cercopithecidae (monkeys) “The Great Apes” “The Great Apes” - monophyletic or paraphyletic? NEW WORLD OLD WORLD Terms used for Phylogenetic Groups
Terms used for Phylogenetic Groups Polyphyletic group Two to multiple origins The given set of taxa forms independent groups each of which is either monophyletic or paraphyletic A B C D E commo n ancesto r Polyphyletic groups are not meaningful in terms of evolutionary history Example of ‘polyphyletic group”? Flying vertebrates (bats, which are mammals, and birds)
Significance of Monophyly The following statement about relationships can only be made about monophyletic groups (clades):

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