Phylogenetic Trees and Cladograms Show the evolutionary relationship among

Phylogeny - the evolutionary history for a group of species. Uses evidence from living species, fossil record, and molecular data shown with branching tree diagrams = phylogenetic trees or evolutionary trees NOTE: Trees are based on hypotheses, not definitive facts.

NOTE: It isn’t the order that matters rather the branching patterns! Phylogenetic trees drawn in many different formats: Phylogenetic trees can be rotated: NOTE: It isn’t the order that matters rather the branching patterns!

Cladistics is classification based on common ancestry. It is a common method to make evolutionary trees called cladograms. classification based on derived traits species placed in order that they descended from common ancestor

Ancestral or Primitive Trait: A characteristic that evolved in a common ancestor. For ex.) Jaws is an ancestral character of the perch and the chimp. Derived Trait: A characteristic that evolved within one group but not another. For ex.) Fur and mammary glands evolved in an ancestor of mice that was not also ancestral to pigeons

more closely related species share more derived characters represented on cladogram as hash marks or dots FOUR LIMBS WITH DIGITS Tetrapoda clade 1 Amniota clade 2 Reptilia clade 3 Diapsida clade 4 Archosauria clade 5 EMBRYO PROTECTED BY AMNIOTIC FLUID OPENING IN THE SIDE OF THE SKULL SKULL OPENINGS IN FRONT OF THE EYE & IN THE JAW FEATHERS & TOOTHLESS BEAKS. SKULL OPENINGS BEHIND THE EYE DERIVED CHARACTER

Cladogram made up of dichotomous branches, with groups of organisms or individual species represented as terminals (the ends of each branch). Each branching point, or node represents divergence from a hypothetical common ancestor. A clade is a group of species that shares a common ancestor.

At each branch point lies the most recent common ancestor of all the groups descended from that branch point. For example:

Differences between phylogenetic trees and cladograms: Many biologists use these terms interchangeably Both are based on ancestral relationships Some scientists associate phylogenetic trees with true evolutionary history Some scientists consider cladograms to represent hypotheses about a group of organisms’ ancestry

In phylogenetic trees, branch lengths can represent the amount of genetic change or are proportional to time In cladograms the branch lengths are usually considered to be arbitrary

PRACTICE VIDEO