Lecture 1 Flashcards
What is systematics?
The scientific study of the sheer variety and diversification of extant and extinct organisms, their relationships and their evolutionary history
Species are directly or indirectly related through what?
Common ancestry
Phylogenetic relatedness is established via what?
Shared characters
Phylogeny is reconstructed using modifications of characters that are what?
Inheritable and Inherited
Organisms may share identical states as a result of what?
Decent from a common ancestor
Whereby a change occurs once and is maintained in descendant lineages
State changes identify groups of organisms and illustrate what?
The hierarchical patterns that exist in nature
How do you define a group of organisms?
Through their common ancestry
What is the definition of a group of organisms?
A statement about its taxonomic memberships
I.e. Usually which species descending from a single common ancestor belong to that group
How do you diagnose a group of organisms?
Through their shared characters
The diagnosis of a group is a statement about what?
A statement about the characters that members of that group have inherited through the process of descent with modification.
What are the two groups of organisms that may belong to the vertebrates?
Hagfish
Lampreys
What are the deuterostome characteristics of vertebrates?
1) Indeterminate cell fate at 8-cell stage
2) Radial cleavage
3) Enterocoely
4) Deuterostomy
What are the Three major groups of extant deuteroatomes?
Echinoderms
Hemichordates
Chordates (including craniates + vertebrates)
What are the diagnostic features of Chordate Deuterosomes?
Notochord - Hollow dorsal nerve chord Spinal ganglia Metameric muscle blocks - Post-anal tail- Pharyngeal slits - Endostyle -
Craniates are sometimes simply referred to as what?
Chordates with a head!
(I.e. Hagfish, lampreys and jawed vertebrates)
The presence of a head is unique to them
