Topic 15 - Phylogeny Flashcards
Outgroup
A sister group that shares a recent common ancestor with the taxa being studied, but is not itself the focus of the study. It is used to the relative timing of evolution of each character.
Monophyletic group
An evolutionary unit that includes an ancestral population and all of its descendants but no others. Also called a clade, or lineage.
Paraphyletic group
A group that includes an ancestral population and some but not all of its descendants.
Convergent evolution
The independent evolution of similar traits in different species due to adaptation to similar environmental conditions and a similar way of life.
Divergent evolution
Evolution that leads to differentiation between populations and species.
Homologous traits
Traits that are similar among organisms of different species due to shared ancestry.
Analogous traits
Result from convergent evolution. Traits that are similar for reasons other than common ancestry.
Parsimony
The logical principle that the most likely explanation of a phenomenon is the one that is most economical or simplest. When applied to comparison of alternative phylogenetic trees, it suggests that the one requiring the fewest character changes is most likely.
Phylogenetic tree
Built based on features such as visible phenotype, anatomy, DNA sequences, protein sequences, behaviour.
Ancestral trait
A character that existed in the ancestor of the species being considered.
Derived trait
A modified form of the ancestral trait, found in a descendant. It can originate via a combination of mutation, selection and genetic drift.
Node
The point where two branches diverge, representing the point in time when an ancestral group split into two or more descendant groups.
Branch
A line representing a population through time
Root
The most ancestral branch in the tree
Tip
Endpoint of a branch; represents a living or extinct group of genes, species, families, phyla or other taxa.
