{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Chapter 26 - Chapter 26 Phylogeny and the Tree of Life...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 26 Phylogeny and the Tree of Life • Overview: Investigating the Tree of Life 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 Concept 26.1: Phylogenies show evolutionary relationships Taxonomy is the ordered division and naming of organisms • Binomial Nomenclature • In the 18th century, Carolus Linnaeus published a system of taxonomy based on resemblances • Two key features of his system remain useful today: two-part names for species and hierarchical classification • The two-part scientific name of a species is called a binomial • The first part of the name is the genus • The second part, called the specific epithet, is unique for each species within the genus • The first letter of the genus is capitalized, and the entire species name is italicized • Both parts together name the species (not the specific epithet alone) • Hierarchical Classification • Linnaeus introduced a system for grouping species in increasingly broad categories • The taxonomic groups from broad to narrow are domain , kingdom , phylum , class , order , family , genus , and species • A taxonomic unit at any level of hierarchy is called a taxon • Linking Classification and Phylogeny
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
• Systematists depict evolutionary relationships in branching phylogenetic trees • Linnaean classification and phylogeny can differ from each other • Systematists have proposed the PhyloCode, which recognizes only groups that include a common ancestor and all its descendents • A phylogenetic tree represents a hypothesis about evolutionary relationships • Each branch point represents the divergence of two species Sister taxa are groups that share an immediate common ancestor • A rooted tree includes a branch to represent the last common ancestor of all taxa in the tree • A polytomy is a branch from which more than two groups emerge • What We Can and Cannot Learn from Phylogenetic Trees Phylogenetic trees do show patterns of descent • Phylogenetic trees do not indicate when species evolved or how much genetic change occurred in a lineage • It shouldn’t be assumed that a taxon evolved from the taxon next to it • Applying Phylogenies • Phylogeny provides important information about similar characteristics in closely related species • A phylogeny was used to identify the species of whale from which “whale meat” originated • Phylogenies of anthrax bacteria helped researchers identify the source of a particular strain of anthrax Concept 26.2: Phylogenies are inferred from morphological and molecular data • To infer phylogenies, systematists gather information about morphologies, genes, and biochemistry of living organisms • Morphological and Molecular Homologies
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}