systematics the study of biological diversity in an evolutionary context
TRANSCRIPT
Systematics
The study of biological
diversity in an
evolutionary context
Systematic Tools
Molecular Comparisons– usually (rRNA or
mtDNA) DNA-DNA
Hybridization Restriction maps DNA Sequence
analysis
Taxonomy
The science concerned with naming and classifying the diverse forms of life
Taxonomic GroupsDomain
Kingdom
Phylum (Division)
Class
Order
Family
Genus
Species
Domains (Table 27.2)
Bacteria Archaea EukaryaCell type Prokaryote Prokaryote Eukaryote
Introns Absent Present Present
RNA Poly One Several Several
P. S. Formyl-methionine
Methionine Methionine
Binomial Nomenclature
Panthera leo
(African Lion)
Binomial Nomenclature
Ardea herodias
(Great Blue Heron)
Classification and Phylogeny
Phylogenetic Groupings Monophyletic
– ancestor and all its descendants
Phylogenetic Groupings Paraphyletic
– ancestor with some but not all its descendants
Phylogenetic Groupings Polyphyletic
– two different ancestors
Phylogenetic Groupings
Similarities
Homology– likeness attributed
to shared ancestry
Similarities
Analogy– likeness due to
similar ecological roles and natural selection due to convergent evolution
Molecular Homoplasy
Analogous species that have similar DNA sequences that evolved independently in two species
Ontogeny Recapitulates Phylogeny (Ernst Haeckel)
Ontogeny – individual development
Recapitulates – repeats
Phylogeny – evolutionary descent
The Science of Systematics
Phenetics
– based on a number of similarities and differences
– does not take into account homology or analogy
– all groupings
Classical Evolutionary Systematics
George Gaylord Simpson
The Science of Phylogenetic Systematics
Classical Evolutionary Systematics
– most commonly used up until recently
– based on shared homologous structures
– takes into account the amount of adaptive evolutionary change (novelties)
– Monophyletic and paraphyletic groupings
The Science of Systematics
Cladistics (Phylogenetic Systematics)– based on shared
homologous structures
– only monophyletic groupings
Will Hennig
The Science of Phylogenetic Systematics
Cladistic Assumptions
1. Monophyletic
2. Descent follows a bifurcating pattern
3. Changes in characteristics occur in lineages over time
Cladistics
Shared primitive characters
– Outgroupings
– Plesiomorphies Ancestral
characteristics Shared derived characters
– Synapomorphies
Phylograms
Ultrametric Trees
Cladistics
Cladistics
Cladistics
Pitfalls
Reptiles?????
Molecular Clock
Tree of Life
Phylogenetic Fuse