Introduction to Classification
I) Classification
a) Taxonomy - system of classification of organisms by means of similarities and differences
II) History
a) Aristotle - placed animals in hierarchy
b) Carolus Linaeus - father of modern taxonomy - Swedish
(a) Systema Naturae
ii) binomial nomenclature
c) Darwin - concept of natural selection
III) Levels of classification – 7 groups = taxa )
1. Domain
2. Kingdom
c) Phylum
d) class
e) order
f) family
g) genus
h) species
IV) 5 Kingdom System
a) Monera - bacteria - all prokaryotic organisms
b) Protista - single celled eukaryotes
c) plantae
d) fungi - kingdoms of multicellular eukaryotes
e) animalia
V) How to write scientific names
a) Rana clamitans (paper you underline) or Rana clamitans (typing is italics)
b) R. clamitans (after you have written full name this is okay)
c) Rana sp.
d) Rana spp.
VI) Why bother with scientific names
i) Latin does not evolve
ii) Universal
VII) Modern Taxonomy
a) Phylogenetic Systematics - classification on basis of evolutionary ties
i) Goal = reconstruct phylogeny (evolutionary tree)
ii) Based on common descent (Darwin)
iii) Evidence ( especially from newer molecular techniques has shown that traditional taxa do not always reflect phylogenetic relationships correctly.
1. Resulted in many changes
2. Including introduction of new level
1. Domain
2. More inclusive than kingdom
i) all life is in one of three domains
1. Bacteria
2. Archaea
3. Eukarya
c) Eliminate Kingdoms Monera and Protista
i) Monera → Archaea and Bacteria
ii) Protista → sev. New groups under Eukarya (no single kingdom for former protista)
d) Animilia, Plantae, and Fungi still exist
iii) Phylogenetic Systematics Uses homologous traits (characters) – to construct branching phylogenetic tree bases on common ancestry
(1) Ancestral (primitive) char. – present in common ancestor
(2) Derived (novel) char. – new – arose within group
(3) Clade = group that shares derived traits
(4) Branches indicate divergence of a new taxonomic group (taxon) from the ancestral group
(5) Locations of branch points indicate relative times of origin of taxa
(6) Degree of divergence represents extent of differences between the groups
(7) Only taxa where all species within the group were derived from the same ancestor tell anything about evolutionary history = monophyletic taxa
(a) Polyphyletic Taxon = group whose members are derived from 2 or more ancestral forms
(i) Do not tell about evolutionary history
1. ex. Kingdom PLantae– contains mosses and vascular plants – derived from dift. Ancestors
(b) Paraphyletic Taxon - exclude species that share a common ancestor with members of that group
(i) Ex. Class reptilia (class aves) although they are all derived from a common ancestor
(8) Characters can be several things
(a) Morphology
(i) Shape, structure, development
(b) Biochemistry
(i) DNA, Proteins
(c) Cytology
(i) Chromosomes