Phylogeny Flashcards
What is an outgroup?
A taxon that is assumed to have diverged earlier than the taxa under study.
What is an unrooted tree in contrast to a rooted one?
A rooted tree provides a direction of evolution, and therefore has an outgroup which is assumed to have diverged earlier than the other taxa. In an unrooted tree, no outgroup is present and there are no assumptions made about which taxa diverged at what timepoint.
What is a cladogram vs a phylogram?
Phylogram: a tree that represents branching patterns and the branch lengths are proportional to the evolutionary distance between species.
Cladogram: only represents the branching patters (topology), and the branch lengths do not represent the evolutionary distance between taxa.
What is a clade/monophyletic group?
A monophyletic group includes an ancestral lineage and all of its descendants.
Visually: a piece of a larger tree that can be cut away with a single cut.
What is a polyphyletic group?
A group constisting of multiple taxa but not the common ancestors
What is a phylogenetic tree?
A graphical representation about evolutionary relationships between species/taxa over time. It can be based on different kinds of data. Modern trees are often based on DNA data, but earlier classification was often done on the basis of morphology.
What is an analogous character?
Similar traits in different taxa which arose due to convergent evolution, i.e not due to a common ancestor. Separate evolutionary origins but similar because natural selection caused them to evolve similarly.
What are cryptic species?
Two or more taxa that are genetically different but are morphologically very similar, which leads to underestimation of species diversity.
What are polymorphic species and what is a common incorrect assumption about them?
A polymorphic species is a species with a large amount of different morphs/phenotypes. This may lead to overestimation to how genetically different the individuals are (e.g assuming they belong to different species).
