phylogeny & cladistics Flashcards
Domain
the highest taxonomic category; above the kingdom level
- Archaea
- Bacteria
- Eukarya
Kingdom
in Linnaean classification, the taxonomic category above phylum
Phylum
in Linnaean classification, the taxonomic category above class
Class
in Linnaean classification, the taxonomic category above order
Order
in Linnaean classification, the taxonomic category above family
Family
in Linnaean classification, the taxonomic category above genus
Genus
in Linnaean classification, the taxonomic category above species; also the 1st part of a binomial is the name of the _____ to which the species belongs
Species
the lowest taxonomic category
Taxon/taxa
a named taxonomic unit at any given level of classification
Basal taxon
refers to a lineage that diverges early in the history of a group and hence lies on a branch that originates near the common ancestor of the group
Sister taxa
groups of organisms that share an immediate common ancestor and hence are each other’s closest relatives
Outgroup
is a species or group of species from an evolutionary lineage that is known to have diverged before the lingeage that includes the species we are studying
Clade
a group of species that includes an ancestral species and all of its descendants
Grade of organization
a group of organisms that share the same level of organizational complexity or share a key adaptation
Monophyletic
“single tribe”
- equivalent to a clade
- consists of an ancestral species and all of its descendants
Paraphyletic
“beside the tribe”
- consists of an ancestral species and some, but not all, of its descendants
Polyphyletic
“many tribes”
- includes distantly related species but not their most recent common ancestor
Shared ancestral character
a character, shared by members of a particular clade, that originated in an ancestor that is not a member of that clade
ex: all mammals have backbones, but a backbone does not distinguish mammals from other vertebrates because all vertebrates have backbones
- the backbone predates the branching of mammals from other vertebrates
Shared derived character
an evolutionary novelty that is unique to a particular clade
ex: hair is a character shared by all mammals but not found in their ancestors
Nodes
represents a branching point from the ancestral population
Dichotomies
a branch point on a tree that has 2 immediate descendents
Polytomies
a branch point on a tree that has more than 2 immediate descendents
Explain how a shared trait can be a shared ancestral character.
all mammals have backbones, but a backbone does not distinguish mammals from other vertebrates because ALL vertebrates have backbones
Explain how a shared trait can be a shared derived character.
hair is a character shared by all mammals but NOT found in their ancestors
Explain what makes a good outgroup.
can be determined based on evidence from:
- morphology
- paleontology
- embryotic development
- and gene sequences
Arrange the taxa in their proper Linnaean hierarchy.
species, genus, family, order, class, phylum, kingdom, domain, life
Identify nodes, dichotomies, and polytomies on a phylogenetic tree.
node: represents a branching point from the ancestral population
dichotomies: a branch point on a tree that has 2 immediate descendents
polytomies: a branch point on a tree that has more than 2 immediate descendents
What is phylogenetics?
- the study of evolutionary relationships between organisms
- the study of phylogenies
What are phylogenies?
evolutionary histories of species or lineages
Hypotheses about these relationships are formed using several different lines of evidence:
- homologus morphology
- the fossil record
- behaviour and habitat
- molecular sequences
Occam’s razor
the simpliest solution tends to be the correct solution
What is the purpose of Phylogenetic trees?
- using the learned characteristics, species can be sorted, & a “tree of life” can be drawn
- also can be drawn to show relationships b/t closely related species
- also to show “all” known species
- the orientation is arbitrary (random)
What do branch lengths mean in phylograms?
more length = more difference
BUT the binomial nomenclature (genus & species together) is always…
unambiguous
