The Major Lineages of Life

The Major Lineages of LifeMolecular data challenges 5 Kingdoms

Monera was too diverse2 distinct lineages of prokaryotes

Protists are still too diversenot yet sorted out

Chapter 26

• Phylogeny is the evolutionary history of a species or group of related species

• The discipline of systematics classifies organisms and determines their evolutionary relationships

• Systematists use fossil, molecular, and genetic data to infer evolutionary relationships

• Taxonomy is the ordered division and naming of organisms

Phylogeny and the Tree of Life

3 Domain system• Domains = “Super” Kingdoms– Bacteria– Archaea• extremophiles = live in extreme environments

– methanogens– halogens– thermophiles

– Eukarya• eukaryotes

– protists– fungi– plants– animals

Archaebacteria&Bacteria

Classification• Old 5 Kingdom system

• Monera, Protists, Plants, Fungi, Animals

• New 3 Domain system– reflects a greater

understanding of evolution & molecular evidence• Prokaryote: Bacteria• Prokaryote: Archaebacteria• Eukaryotes

– Protists– Plants– Fungi– Animals

Prokaryote

Eukaryote

KingdomProtista

KingdomFungi

KingdomPlantae

KingdomAnimalia

KingdomArchaebacteria

KingdomBacteria

Kingdoms

Single-celled ancestor

prokaryotes eukaryotes

Eubacteria Archaebacteria

Protista

multicellularuni- tomulticellular

autotrophs heterotrophs

Plantae

Fungi Animalia

absorptivenutrition

ingestivenutrition

• Organisms classified from most general group, domain, down to most specific, species– domain, kingdom,

phylum, class, order, family, genus, species

Finding commonality in variety

use the mnemonic!

The Evolutionary Perspective

Phylogenies are inferred from morphological and molecular data

• To infer phylogenies, systematists gather information about morphologies, genes, and biochemistry of living organisms

• Organisms with similar morphologies or DNA sequences are likely to be more closely related than organisms with different structures or sequences

Cladistics

• Cladistics groups organisms by common descent• A clade is a group of species that includes an

ancestral species and all its descendants• Clades can be nested in larger clades, but not all

groupings of organisms qualify as clades