Lecture 21.docx

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18 Apr 2012
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Lecture 21
Macroevolution- phylogenics
Relates to classification
- great diversity in phenotypes. How o put in taxonomic heirchy
- darwins said that all organisms are related as seen on his tree of life
carolous Linnaeus *
-Invented system of classifying life still used today. Binomial nomenclature and
heirchal system. Homo-sapien
purpose of classification
-efficient way of storing info
- Predictive power
- Allows for interpretation of origins and evolutionary history
Definitions
taxon: a named taxonomic unit at any level. Taxa is plural
taxonomy: the theory and practice of classification
systematics: the study of biodiversity and the evolutionary relationships among
organisms.
Two schools of taxonomy
Phonetics: classifying species based solely on resemblance. DEAD. Convergent
evolution.
Cladistics: -classifying species on the basis of their phylogenetic relationships
- Willi hennig built phylogenic tree. Cladistics analysis to build tree. Depiction of
evolutionary history.
Know phylogenetic tree
Taxa are the letters
Internodes are common ancestor
Nodes are speciation event
-based on monophyletic group. A single ancestor that gives rise to all speices in that
taxon and no species in any other. Constitutes a clade.
- non monophyletic group. Not used. Immediate ancestors in different groups
critical step: identify ancestral trait. Diffiernt from derived trait, which is a trait that
differs from ancestors. We use ancestral
- homoplasy similarity of traits as a result of convergent evolution. (lead to
downfall and beginning of phonetics)
- homology- sharing of triat because of shared ancestry
convergent evolution:
ecoogy drives orgaisms to look similar as a result of animals getting similar
functions due to similar habitats
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