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Lecture

BISC 316 Lecture Notes - Evolutionary Taxonomy, Phenetics, Carl Linnaeus


Department
Biological Sciences
Course Code
BISC 316
Professor
Tammy Mc Mullan

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Lecture 2 – BISC 316 Vertebrate Biology Summer 2011
Classification = grouping of organisms
taxonomy = the naming and classification of species
phylogeny = the evolutionary history of a species or group of related species
systematics = the study of biological diversity in an evolutionary context
WHY ARE WE CONCERNED WITH THE CLASSIFICATION OF
ORGANISMS
-museums
-conservation biology and biodiversity
-understanding the biology of vertebrates requires an appreciation of the diversity of
the organisms that make up this group
where did the science of classification start?
-systematics/taxonomy
-concerned with the diversity of organisms
-originally designed by Carl Linneaus
-organisms are grouped into taxa (singular=taxon)
-originally based on similarities
-now based on evolutionary relationships
Hierarchy of Classification
Kingdom
Phylum
Class
Order
Family
Genus
Species
Species: the basic unit; a group of naturally interbreeding populations that are
genetically isolated from other groups.
Rules for Classification
1. 'Narrow' taxa - subsets of 'broader' taxa
-> each higher taxon is an assemblage of evolutionary related lower taxa
-> at Order level and above - shared structural features
www.notesolution.com

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2. Broader taxa have fewer characteristics common to all members of the taxon
-> ancestral features
3. Broader taxa originated earlier in evolutionary time
Phylogenetic Trees
-relationship between organisms
-two significant structural features
1. location of the branch point
-> relative time of origin of different taxa
2. extent of divergence between the two taxa
-> divergence from the common ancestor
If classification is based upon the evolutionary history of the group, which property
should be given the most weight?
-> three different approaches to classification
1. Phenetics
2. Cladistics
3. Classical evolutionary systematics
1. Phenetics or Numerical Taxonomy
- less subjective
-no phylogenetic assumptions
- taxonomic affinities based entirely on measurements
-uses many anatomical characteristics
-reduced bias
-homology vs. analogy
- computer analysis of multiple quantitative comparisons
-important toll
-molecular comparison
x critics - overall phenotypic similarity is not reliable index of genotypic
proximity
2. Phylogenetic Systematics or Cladistics
-Classifies organisms based upon the branching pattern in the Cladogram
-> each taxon evolved by the dichotomous splitting from the sister group
www.notesolution.com
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