Chapter 20 (BIO II)

Monophyletic

Consists of the ancestor species and all its descendants; All taxa linked to one common ancestor

Paraphyletic

Group consists of an ancestral species and some, but not all, of the descendants.

Polyphyletic

Group includes distantly related species but does not include their most recent common ancestor.

Shared Derived Characteristic

A trait unique to a specific clade and not found in it ancestors

ex; hair in mammals

Shared Ancestral Character

A trait that originated in an ancestor of the group

All or most lineages in the clade

Horrizontal Gene Transfer

Permits gene flow from one organism's genome to another organism's genome

-Occurred frequently in the early history of the three domains on Earth and makes determining phylogenetic relationships of that time difficult

Parsimony

The phylogenetic tree requiring the fewest evolutionary changes (mutations or trait gains/losses) is most likely correct.

Phylogeny

The evolutionary history of a species or group of related species

Phylogenetic Tree

A diagram that represents a hypothesis about evolutionary relationships

Root of a Phylogenetic Tree

Single lineage at the base of the tree representing the common ancestor of all organisms in the diagram

Node of a Phylogenetic Tree

A split point representing a common ancestor dividing into new descendant lineages

Branch of a Phylogenetic Tree

Represents the divergence of two evolutionary lineages from a common ancestor.

Taxon / Taxa of a Phylogenetic Tree

Any named group of organisms located at the node of a branch

Basal Taxon of a Phylogenetic Tree

A lineage that diverges from all members of its group early in the group’s history & stays unbranched

Polytomy

A branch with more than two descendant groups; an unresolved evolutionary relationship

Sister Taxa

Groups that share an immediate common ancestor not shared by any other group.

Taxonomy Groups (Broad to Specific)

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

Homologous Traits

Similar features shared by organisms because they inherited them from a common ancestor

Analogous Traits

Similar features that evolved independently due to similar environmental pressures through convergent evolution

Define Clade

A group of species that includes an ancestral species and all its descendants

How can we use phylogeny and fossils to form evidence of evolution?

Fossils provide physical evidence of transition species and dates that confirms predictions made by phylogenetic trees

Molecular Clock

Method uses constatn rates of DNA