- Evolution is the scientific explanation for the diversity of life on earth.
- Diversity of species is developed through gradual changes over many generations.
- Organisms are classified into groups and subgroups based on similarities that reflect their evolutionary relationship and common ancestry.
- There is unity among organisms despite the diversity.
- Organisms can be classified based on physical similarities.
- The modern classification is based on evolutionary relationships.
- Cladistics is the classification based on common ancestry.
- The present day hierarchical scheme is subjective and subject to changes with ongoing evidence.
- The process of evolution produces a pattern of relationships between species. As lineages evolve and split and modifications are inherited, their evolutionary paths diverge. This produces a branching pattern of evolutionary relationships.
- The studying of inherited species' characteristics and other historical evidence, scientist can reconstruct evolutionary relationships and represent them on a "family tree", classed a phylogeny.
History of TaxonomyUntil 1866: Only two kingdoms, Animalia and Plantae
– 1938: Prokaryotes moved to kingdom Monera
– 1866: All single-celled organisms moved to kingdom Protista
– 1959: Fungi moved to own kingdom
– 1977: Kingdom Monera split into kingdoms Bacteria and Archaea
Domains were proposed by Carl Woese based on rRNA studies of
prokaryotes. Domain model more clearly shows prokaryotic diversity.
Traditional Classification & Phylogenies
Phylogenies: Evidence from morphological, biochemical, and gene sequence data suggests that all organisms on Earth are genetically related, and the genealogical relationships of living things can be represented by a vast evolutionary tree, the Tree of Life.
Traditional Classification: Physical Similarities.
Linnaeus's Levels of Classification
Why are scientific names more useful to scientist than common names?
Scientific names help scientists to communicate.
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