Biology II The Materials for Quiz II
Biology II The Materials for Quiz II Biology 1082
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This 7 page Class Notes was uploaded by Abtin Notetaker on Thursday January 21, 2016. The Class Notes belongs to Biology 1082 at University of Cincinnati Blue Ash College taught by Mark Otten in Spring 2016. Since its upload, it has received 85 views. For similar materials see Biology II in Biology at University of Cincinnati Blue Ash College.
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Date Created: 01/21/16
The Material On Quiz #2 Cladogram: represents patterns of evolutionary relatedness but no measure of divergence. Phylogram: shows patterns of evolutionary relatedness and a measure of divergence. The basic unit of a cladistics is a clade, or a common ancestor and all of its descendants. In other words, a clade represents a branch on a cladogram. A clade does not have a defined taxonomic equivalent and may encompass several taxonomic levels. A Traditional Cladogram: Purpose- show evolutionary relationship among groups of interest Groups may or may not be actually taxonomic categories Not attempting to show time or magnitude of evolution since it disappears. Lemurs-Humans are your terminal branches. Your lemurs (out-group): is the group that is known to have diverged earlier than other groups and is used for comparative reasons Nodes (branch points) represent a common ancestor to the groups above and to the right of it. For example your node on the terminal branch of Tarsiers represents the common ancestor for Tarsiers and above. Clade (New world monkeys, old world monkeys, Apes, and Humans): this clade represents the the the common ancestor for New world monkeys and up, and all of the descendants ranging from New world monkeys-Humans. Plylogram- Uneven branch lengths and uneven clade positions Purpose- show patterns of evolutionary relationship and some measure of evolutionary change since divergence from common ancestor All groups are contemptuous Variable Length of Terminal Branches: shows the different evolutionary change since divergence from common ancestor. Short= smaller change , Long= greater change Despite this, how do we measure or indicate magnitude of evolutionary change? Genetic divergence- several ways to measures Measures in morphologic feature (number of bristles, wing length, etc) Phylogram- Uneven Branch Lengths and even clade position (not important for quiz but for your general knowledge and midterm) Show hypothesized evolutionary relationship Indicates common ancestry Time factor of divergence is included Does not indicate magnitude of change/ divergence. ( I will not include picture because we know what is looks like) Every Clad Positon of all the groups are still alive, and to represent an extinct species we draw a line shorter than the rest. *The lines are not used to represent magnitude of change but the time frame in which the being is alive* *** What Cladograms and Phylograms can tell us*** 1.Evolutionary relationships: both cladograms and phylograms 2.Common Ancestry: both cladograms and phylograms 3.Magnitude of genetic divergence: Phylograms only and it must include uneven branch lengths/value of genetic divergence and or both 4.Timing of Divergence: Phylograms only, must include some time frame Depicting Derived Characters: This is a classic cladogram showing evolutionary relationships Based on the presence, absence, or state of certain key characters. Key Characters- reveal the evolutionary relationships among groups 1.Vertebral column represents a key character and every group to the right of that character expresses that character 2.The Hole in the pocket represents a unique character that exists only on the terminal branch (in this case T-rex and Bird) 3.Plesimophy (Ancestral character)- A character or character that occurs in the common ancestor of a defined clade or taxonomic group. In this case, the clad of Lamprey-Gorilla has a Plesimophy of Vertebral column. 4.Apomorphy (Derived character)- A character or character that state that occurs in a clade or taxonomic group but does not occur in the ancestral species (For example the Prehensile hand in the clad of Cow-Gorilla because only Humans and Gorillas posses that trait, not the cows and the common ancestor of the clade. 5.Homoplasy- a character or character state shared among species that was not inherited from common ancestor. This is traits that species develop in order to adapt to their environment. 6.Parsimony- When developing a cladogram, you may not be able to get all the information. So scientists developed parsimony as a way of determining the best cladogram for a specific clade. “The least change is the most parsimonious” that means that the least changes that occurred during the evolution of a clade is the most likely to happen. Now is that the correct way? We don’t know.. Monophyletic grouping- it is only if it includes the most recent common ancestor of the group and all its descendants. By definition, a clade is a monophyletic group. Paraphyletic grouping- if it includes the most recent ancestor but not all of its descendants. Polyphyletic grouping- If it does not include the most recent common ancestor of all members of the group. Section 20.4: Molecular Clocks help Track Evolutionary Time Define or describe the concept of a molecular clock An approach for measuring the absolute time of evolutionary change based on the observation that some genes and other regions of genomes appear to evolve at constant rates. What are some genes or regions of the genome not suitable as molecular clocks? Some portions of the genome appear to have evolved in irregular bursts that are not clocklike and would be reliable ways to determine using a molecular clock. What are some problems with using molecular clocks? Molecular clocks do not run as smoothly if the underlying mutation were selectively neutral. This is what is going to be covered on the quiz. Use this material well
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