Lecture 2

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University of Toronto St. George
Ecology & Evolutionary Biology
James Eckenwalder

EEB330H1 S Systematic Botany - James Eckenwalder Lecture 2 January 17, 2013 Everything above the number in the phylogeny tree has a 1 and anything below has a 0. This is an indication of relationship. Phylogenetic and phenetic approach are post-WWII techniques Phylogenetic school - only information on the tree that is considered important is the series of branching events. And those are in essence speciations and times in the past. What they imply is a relative recency of common ancestor. This depends only on cladistic information. All groupings represented have to be monophyletic (group in which if you take any two members of the same group and find their most common ancestor, look for the descendents of the common ancestor and this is included in the group) Phenetic approach uses only the distribution of character states and we use only characteristic information. The evolutionary approach is traditional taxonomy. It uses all the information that is available. This also takes into account the change that has occurred. Parallelism Plesiomorphies Synapomorohies imply monothetic groupings. Paraphyletic Polyphyletic - ex. Grouping Populus trichocarpa and Salix due to the hair characteristic. Polythetic groups are ones in which the characters within the group are in essence scrambled and mixed up. No singly character in a polythetic grouping is necessary or sufficient for grouping. Not all of the taxa within a polythetic grouping can have any of the grouping characters; some members will be lacking it. Each members have a preponderance of the characters and nothing outside of the group do the characters predominate, they will exist scattered outside of the group however. Monothetic groups in which a single character may be necessary or sufficient for group membership. Ex. Characters 6 and 5 are clear synapomorphies. APG3 - angiosperm phylogeny group is the most prominent traditional classifications. This will be contrasted with Cronquist, which is one of the last traditional classifications. Many APG groupings are very messy. There are also many parallelisms and reversals in characters. Organization of figure 1-2 is hierarchical. The nesting of groupings are hierarchical organizations; there are groups within groups. Figure 1
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