BCOR 12 1st Edition Lecture 7 Outline of Last Lecture I Macro and microevolution II Reclassification of species III Allopatric speciation and sympatric speciation IV Hybrid Zone Outline of Current Lecture I Definition of phylogeny and phylogeny data II Hierarchy of Life III Key Points about Phylogenies IV Shared Characters V Clades phyletic groups VI Types of characters used for Phylogenetic Trees Current Lecture Phylogeny represents the evolutionary species or a group of species Phylogenies show evolutionary relationships and illustrate the pattern of macroevolution Types of data used ton contrast phylogenies o Fossil record o Morphological data o Biochemical data o Genetic data Phylogenies are HYPOTHESES They are changing constantly Hierarchy of Life From bottom to top this figure shows the hierarchy of life starting with the most inclusive life domain to the most exclusive species These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Figure obtained fromhttp en wikipedia org wiki Biological classification Key Points about phylogenies I the sequence of branching in a tree reflects the patterns of descent speciation BUT does not indicate the absolute age of a particular taxon unless as axis is specifically labeled with time II A taxon in a phylogeny did not evolve from an adjacent taxon Taxon group of organisms you see on a phylogenetic trees taxon below is all labeled organisms Example In the phylogeny above organism 4 DID NOT evolve from organism 3 but rather they both evolved from organism 1 Any ancestor farthest to the left Ex Common Ancestor is the oldest common ancestor A phylogenetic tree is a branching diagram that represents a hypothesis about the evolutionary history of a group organisms Branch point in a phylogeny node speciation occurred Taxa that are most closely related are sister taxa Ex In the phylogeny above organisms 3 4 are sister taxa for they share a more recent common ancestor than 1 2 Polytomy a branch point from which two or more descendent groups emerge o This shows that more evidence is needed to find the proper moments of species If a phylogenic tree has a time line and a branch point doesn t reach the label Present then that organisms no longer exists The more recent the branch point between two organisms the more closely related they are Hominin contain human like characteristics are closely related to genus Homo Characters Character any feature a particular taxon possesses Shared Character characters used to construct a phylogenetic tree Biologists place species into clades Clade a common ancestor and ALL of its descendants on a phylogenetic tree Monophyletic group a clade Paraphyletic group part of a clade that are all a part of the same genus order etc Polyphyletic group multiple clades Two major types of characters used to construct phylogenies Shared ancestral character a character shared by members of a clade that originated from an ancestor o All organisms that are vertebrates have backbones shared from a common ancestor that also had a backbone Shared derived character an evolutionary novelty that in UNIQUE to a particular clade o Mammals have hair while other vertebrates do not This is unique to the clade of mammals