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UVM BCOR 012 - Phylogeny and the Hierarchy of Life
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BCOR 12 1st Edition Lecture 7Outline of Last Lecture I. Macro- and microevolutionII. Reclassification of speciesIII. Allopatric speciation and sympatric speciationIV. Hybrid ZoneOutline of Current Lecture I. Definition of phylogeny and phylogeny dataII. Hierarchy of LifeIII. Key Points about PhylogeniesIV. Shared CharactersV. Clades & phyletic groupsVI. Types of characters used for Phylogenetic TreesCurrent 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 phylogenieso Fossil recordo Morphological datao Biochemical datao Genetic data- Phylogenies are HYPOTHESES! – They are changing constantlyHierarchy of LifeFrom 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 phylogeniesI. 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 timeII. 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 theyare- 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 cladesTwo major types of characters used to construct phylogenies- Shared ancestral character – a character shared by members of a clade that originated from an ancestoro 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 cladeo Mammals have hair while other vertebrates do not. This is unique to the clade of


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UVM BCOR 012 - Phylogeny and the Hierarchy of Life

Type: Lecture Note
Pages: 3
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