McGraw Hill Chapter 25

Taxonomy and Systematics

Key Concepts:

•Taxonomy

•Phylogenetic Trees

•Cladistics

•Molecular Clocks

•Horizontal Gene Transfer

•Taxonomy

Science of describing, naming, and classifying living and extinct organisms and viruses

•Systematics

Study of biological diversity and the evolutionary relationships among organisms, both extinct and modern

•Taxonomic groups are based on hypotheses regarding evolutionary relationships derived from systematics

•Hierarchical system involving successive levels

•Each group at any level is called a taxon

•Highest level is Domain

All of life belongs to one of 3 domains

Bacteria, Archaea, and Eukarya

•Previously kingdom was the highest (Linnaeus)

Taxonomic hierarchy

Supergroup between a domain and a kingdom

•7 eukaryotic supergroups

Below domain and supergroup is Kingdom

Phyla

Class

Order

Family

Genus

Species

Binomial nomenclature

•Every species has genus name and species epithet

•Example: Homo sapiens

•Genus name always Capitalized

•Species epithet never capitalized

•Both names are italicized

•Rules for naming established and regulated by international associations

Phylogeny

•Phylogeny – evolutionary history of a species or group of species

•To propose a phylogeny, biologists use the tools of systematics

•Trees are usually based on morphological or genetic data

•Diagram that describes phylogeny

•A hypothesis of evolutionary relationships among various species

•Based on available information

•New species can be formed by

Anagenesis – single species evolves into a different species

Cladogenesis – a species diverges into two or more species

Branch point in a phylogenetic tree are called nodes

•Times when cladogenesis has occurred

•Group species according to common ancestry

Clade consists of a common ancestral species and all of its descendant species