Studied by 3 people
Phylogeny
the evolutionary history of a species or group of related species
systematics
classifies organisms and determines their evolutionary relationships
Systematists use ___ to infer evolutionary relationships
fossil, morphological, and molecular data
Taxonomy
the ordered division and naming of organisms
Carolus Linnaeus published a system of taxonomy based on
resemblances
binomial
The two-part scientific name of a species
genus
the first part of the name
specific epithet [i.e., species]
the second part of the name, unique for each kind within the genus
the taxonomic groups from broad to narrow
domain, kingdom, phylum, class, order, family, genus, and species
taxon
A taxonomic unit at any level of hierarchy
Systematists depict evolutionary relationships in branching
phylogenetic trees
A phylogenetic tree represents a
hypothesis about evolutionary relationships
each branch point represents
the divergence of two species
Sister taxa
groups that share an immediate common ancestor
a rooted tree includes
a branch to represent the last common ancestor of all taxa in the tree
basal taxon [outgroup]
diverges early in the history of a group and originates near the common ancestor of the group
polytomy
a branch from which more than two groups emerge
Phylogenetic trees show ____ not ____
patterns of descent, phenotypic similarity
Phylogenetic trees typically do not indicate
when species evolved or how much change occurred in a lineage
To infer phylogenies, systematists gather information about
morphologies, genes, and biochemistry of living organisms
homologies
Phenotypic and genetic similarities due to shared ancestry
When constructing a phylogeny, systematists need to distinguish whether a similarity is the result of
homology or analogy
Homology
similarity due to shared ancestry
analogy
similarity due to convergent evolution
bat and bird wings are homologous as
forelimbs
bat and bird wings are analogous as
functional wings
Convergent evolution occurs when
similar environmental pressures and natural selection produce similar [analogous] adaptations in organisms from different evolutionary lineages
Molecular systematics
uses DNA and other molecular data to determine evolutionary relationships
Cladistics
groups organisms by common descent
clade
includes an ancestral species and all its descendants
monophyletic grouping
a valid clade, consists of the ancestor species and all its descendants
paraphyletic grouping
consists of an ancestral species and some, but not all, of the descendants
polyphyletic grouping
consists of various species with different ancestors
What type of grouping is this?
monophyletic
What type of grouping is this?
Paraphyletic
What type of grouping is this?
Polyphyletic
shared ancestral character
a character that originated in an ancestor of the taxon
ex. vertebratal column
shared derived character
an evolutionary novelty unique to a particular clade
ex. hair
outgroup
species or group of species that is closely related to the ingroup
ingroup
the various species being studied
Systematists compare each ingroup species with the outgroup to differentiate between
shared ancestral and shared derived characteristics
In some trees, the length of a branch can reflect the
number of genetic changes that have taken place
Methods of narrowing the possibilities of the best phylogenetic tree
maximum parsimony and maximum likelihood
Maximum parsimony assumes that
the tree that requires the fewest evolutionary events [appearances of shared derived characters] is the most likely
maximum likelihood states that
given certain rules about how DNA changes over time, a tree can be found that reflects the most likely sequence of evolutionary events
Phylogenetic bracketing
allows us to predict features of an ancestor from features of its descendents
What are some shared features of birds and crocodiles?
four-chambered hearts, vocalization, nest building, and brooding
The shared features of birds and crocodiles likely evolved in a
common ancestor
The shared features of birds and crocodiles were
shared by all of its descendants, including dinosaurs
What is a valuable approach for tracing organisms’ evolutionary history?
Comparing nucleic acids or other molecules to infer relatedness
Ribosomal RNA changes
relatively slowly
Ribosomal RNA is useful for investigating
branching points hundreds of millions of years ago
mtDNA evolves
rapidly
mtDNA can be used to
explore recent evolutionary events
-nae
sub family
-dae
family
What are the three domains?
the Archaea, the Bacteria, and the Eukarya
