Theme 5A Flashcards
node
in phylogenetic trees, the point where a branch splits, representing the MOST RECENT common ancestor from which the descendant species diverged.
phylogenetic tree
a diagrammed hypothesis about the evolutionary history, or phylogeny, of a species
sister groups
groups that are more closely related to each other than either of them is to any other group
taxon
all the species in a taxonomic entity such as family or genus
monophyletic
describes groupings in which all members share a single common ancestor not shared with any other species or group of species
paraphyletic
describes groupings that include some, but not all, the descendants of a common ancestor
polyphyletic
describes groupings that do not include the last common ancestor of all members
character
in the discipline of systematics, an anatomical, physiological, or molecular feature of an organism that varies among closely related species
character states
the observed condition of a character, such as presence or absence of lungs or arrangement of petals
how are phylogenetic trees constructed?
by comparison of character states shared among different groups of organisms
homologous
describes characters that are similar in different species because of descent from a common ancestor
analogous
describes similar characters that evolved independently in different organisms as a result of adaptation to similar environments: i.e. CONVERGENT EVOLUTION
synapomorphy
a shared derived character; a homology shared by some, but not all, members of a group: MOST IMPORTANT FOR BUILDING PHYLOGENETIC TREES
cladistics
phylogenetic reconstruction on the basis of shared evolutionary changes in characters, often called synapomorphies
parsimony
choosing the simplest hypothesis to account for a given set of observations
