Phenetics vs Cladistics Flashcards
- numerical taxonomy
- similarity
phenetics
phenetics is also called
taximetrics
- method of hypothesizing relationships among organisms
- method of reconstructing evolutionary trees
Cladistics
study of evolutionary relationships among biological entities – often species, individuals or genes (which may be referred to as taxa)
Phylogenetics
Phenetics group organisms based on __ _ __
degree of similarity
early phenetics is based more on __ or __
- morphological
- anatomical
branching diagrammatic tree used in phenetic classification to illustrate the degree of similarity among taxa
phenogram
phenetics does not relate __ __
evolutionary relationships
- diagram that shows relationships between species
- relationships are based on observable physical characteristics
- show the relationships in a graphic that looks like a tree, with branches connected to a common ancestry
Cladograms
Cladograms are based on __ __, whereas phenograms do not consider __ __
- ancestral assumptions
- evolutionary history
Within a cladogram, a branch that includes a single common ancestor and all of its descendants
clade
some cladograms are __ wherein timeline and genetic distance are shown
scaled
in cladistics, organisms are arranged due to __ __ __
unique derived characteristics
- specialized trait or character that is unique to a group or species
- a character state (such as the presence of feathers) not present in an ancestral form
apomorphy
- ancestral trait
- evolutionary trait that is homologous within a particular group of organisms but is not unique to members of that group (compare apomorphy) and therefore cannot be used as a diagnostic or defining character for the group
plesiomorphy
idea that embryonic development repeats that of one’s ancestors
recapitulation
defined as a collection of one or more populations of organisms
taxon
- shared, derived character state
- apomorphy that two taxa share and that is assumed to have been present in the common ancestor of those two taxa
Synapomorphy
- shared, ancestral character state
- any trait that was inherited from the ancestor of a group and has been passed on into more than one descendant lineage
Symplesiomorphy
- derived trait that is unique to a particular taxa
- not useful in determining how groups are related since only one group will have the particular trait
Autapomorphy
- clade, species, or lineage that appears at the tip of a phylogenetic tree
- may be extant or extinct
Terminal taxon
- A lineage that evolved early from the root and remains unbranched
basal taxon
two lineages stem from the same branch point
sister taxa
diagram that depicts the lines of evolutionary descent of different species, organisms, or genes from a common ancestor
phylogenetic tree
- quantitative analysis of form
- concept that encompasses both the size and shape of an organism or organ
Morphometrics
‘the ability of individual genotypes to produce different phenotypes when exposed to different environmental conditions’
Phenotypic plasticity
1960s onward
genetic evidence
SNPs
single nucleotide polymorphism
change in one DNA base pair
single nucleotide polymorphism (SNP)
- mutation named with the blend of insertion and deletion
- length difference between two ALLELES where it is unknowable if the difference was originally caused by a SEQUENCE INSERTION or by a SEQUENCE DELETION.
indel
Animal taxonomy:
Family suffix
-idae
principle that, out of all possible explanations for a phenomenon, the simplest of the set is most likely to be correct
parsimony
UPGMA
Unweighted Pair Group Method with Arithmetic Mean
- A simple clustering method that assumes a constant rate of evolution (molecular clock hypothesis)
- needs a distance matrix of the analysed taxa that can be calculated from a multiple alignment.
UPGMA (Unweighted Pair Group Method with Arithmetic Mean)
What to look for in a phylogenetic tree
- ancestor
- clade
- monophyletic group
- terminal and basal taxa
- branch points
- sister group (ingroup)
- outgroup (different genera)
- node on a phylogeny where more than two lineages descend from a single ancestral lineage
- may indicate either that we don’t know how the descendent lineages are related or that we think that the descendent lineages speciated simultaneously.
polytomy
node terminates a branch
branch point
- represents a group
- depends on point of reference
clade
lineage that evolved early from the root and remains unbranched
basal taxon
Different kinds of groups
- monophyletic group
- polyphyletic group
- paraphyletic group
A single common ancestor and all of its descendants.
Monophyletic group
A common ancestor and some of its descendants
Paraphyletic group
- A grouping with no recent common ancestor.
- composed of unrelated organisms descended from more than one ancestor
Polyphyletic group
