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BIOL 103 Lecture Notes - Carl Linnaeus, Botany, Phonetics

Course Code
BIOL 103
Peter T Boag

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Systematics and reconstructing Phylogeny
- Systematics
o Scientific study of the diversity of organisms and their evolutionary
relationships and origins
- Taxonomy = practical side of systematics
o Naming, describing, classifying organisms
o Group at any level = taxon, plural = taxa
- Classification
o Grouping organisms by their similarities (e.g. phonetics) or
relationships in a system which today are based on sound
evolutionary principles
- Why classify organisms?
o Classifications arrange organisms into groups based on similarity
(phenotypic = phonetic & evolutionary), with the goal of revealing
historical relationships
o Classification systems explain relationships among things, aid our
memory and record-keeping, and provide unique, universal names for
o ‘dead’ languages such as Latin used for names = stability and
international usage
- Binomial nomenclature
o Genus + specific epithet (species name)
Homo sapiens
Quercus alba
o Linnaeus designed system used today in 1735, before Darwin and
evolution by natural selection known
o Facilitates international science
o Note: above species, classification levels are ‘artificial’, and vary with
organism type
o DNA similarities potentially more natural, but still likely to vary
greatly between taxa
- Hierarchical Classification of Species
o Swedish botanist Linnaeus developed the hierarchical ‘Linnaean’
system of classification; species grouped into higher-level units:
Genus, Family, Order, Class, Phylum, Kingdom, Domain
o At higher levels, broader range of variation evident, along with fewer
shared traits common to all members
- Evolutionary Phylogeny
o Evolutionary history of group of organisms derived from a common
o Classification ultimately based on common ancestry
o Traditionally based on structural and other phenotypic similarities;
these can be problematic due to convergent evolution
- Elements and terms used to describe phylogenetic trees
o Node A represents the common ancestor to all taxa in the tree
o Extreme polytomy sometimes called ‘star phylogeny’
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