Cladistic Terms Flashcards
(25 cards)
anagenesis
Change occurring within a lineage
ancestral (primitive) state
plesiomorphic
the character state exhibited by the ancestor form which current members of a clade have evolved
apomorphy
any derived or specilized character
autapomorphy
a derived character possessed by only one descendant of an ancestor, and thus no use in discerning relationship among other descendants
bayesian inference
a statistical technique used to infer the probability that a particular phylogenetic hypothesis is correct
bootstrapping
technique to evaluate reliability of branch of phylogenetic tree by resampling some characters form original data set
clade
a group of organisms that includes the most recent common ancestor of all its members and all descendants of that ancestor; every valid clade is “monophyletic group”
cladogenesis
the splitting of a single lineage into two or more distinct lineages
cladogram
the pictorial representation of branching sequence that are characterized by particular changes in key morphological or molecular characteristics
derived state
apomorphic state
an altered state modified form original or ancestral condition
homologous characters
homology
characters that have the same evolutionary origin form a common ancestor, often coded for by the same genes
homoplasy
the independent acquisition of similar characteristics (character states) form different ancestors though convergent or parallelism. create illusion of homology
jackknifing
technique for evaluating the reliability of a branch of phylogenetic tree by deleting some percentage of info at random and then rerunning the analysis
monophyletic taxon
a gorup of species that evolved forma. single ancestor and includes all descendants of that ancestor
node
a branching point on cladogram
outgroup
a group of taxa outside the group being studied
paraphyletic group
a group of species sharing immediate ancestors but not including all descendants of ancestor
parsimony
least complex is usally anser
pleisiomorphy
any ancestral or primative character
polarity
the direction of evolutionary change
polyphyletic grouping
incorrect grouping containing species that descended form two or more different ancestors. independently evolved similar traits by different ancestors
saturation
situation in which the gese sequences being compared have experinced so many base-pair substitutions that the phylogenetic signal is largely lost
sister gorups
tow groups of animals descended from the same immediate ancestor
synapomorphy
derived character that is shared by the most recent common ancestor and by two or more descendants of that ancestor. define clades. homologous characters taht defien clades
