Lecture 4 - taxonomy and phylogeny Flashcards
define taxonomy
grouping organisms together into more alike species/genera
a binomial system invented in 1700’s
where does speciation occur?
at the population level NOT the species level
problems with taxonomy in the past
- evolutionary relationships were achieved through hunches
2. both presence and absence of characteristics were considered
define homoplasy
a character shared by a set of species but not present in their common ancestor
define synamorphy
a characteristic present in an ancestral species and shared exclusively by its evolutionary descendents
define symplestiomorphy
an ancestral character or trait state shared by 2 or more taxa
define homologous character
derived from a common ancestor
define analogous character
derived from conversion
what is a cladistic analysis?
an analysis of character distributions using parsimony or bayesian methods
establishes sister groups rather than ancestor-descendent relationships
define monophyletic group
all descendents from a common evolutionary ancestor / ancestral group
what is a crown group?
includes the most basal of the living member if the group and everything that evolved from it
what is a stem group?
there is nothing living in it
total group =
stem group + crown group
*useful for working out how characters today evolved
dinosaurs are a monophyletic group as long as?
birds are included
what is the main character that people used to look at when classifying dinosaurs?
the pelvis structure
