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Biodiversity
Chapter 26 vocab
38
Biology
Undergraduate 1
03/16/2011

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Term
phylogeny
Definition
the evolutionary history of a species or group of related species
Term
systematics
Definition
a scientific discipline focused on classifying organisms and determining their evolutionary relationships
Term
taxonomy
Definition
a scientific discipline concerned with naming and classifying the diverse forms of life
Term
binomial
Definition
the two-part latinized name of a species, consisting of the genus and specific epithet.
Term
genus
Definition
A taxonomic category above the species level, designated by the first word of a species' two-part scientific name
Term
family
Definition
In classification, the taxonomic category above genus.
Term
order
Definition
In classification, the taxonomic category above the level of family
Term
class
Definition
In classification, the taxonomic category above the level of order
Term
phylum
Definition
In classification, the taxonomic category above class
Term
kingdom
Definition
A taxonomic category, the second broadest after domain
Term
domain
Definition
A taxonomic category above the kingdom level. The three ___ are Archaea, Bacteria, and Eukarya
Term
taxon
Definition
a named taxonomic unit at any given level of classification
Term
phylogenetic tree
Definition
A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms
Term
PhyloCode
Definition
System of classification of organisms based on evolutionary relationships: Only groups that include a common ancestor and all of its descendants are named
Term
branch point
Definition
The representation on a phylogenetic tree of the divergence of two or more taxa from a common ancestor. Most ___ are shown as dichotomies, in which a branch representing the ancestral lineage splits (at the ___) into two branches, one for each of the two descendant taxa.
Term
sister taxa
Definition
Groups of organisms that share an immediate common ancestor and hence are each other's closest relatives
Term
rooted
Definition
Describing a phylogenetic tree that contains a branch point (typically, the one farthest to the left) representing the last common ancestor of all the taxa in the tree.
Term
polytomy
Definition
In a phylogenetic tree, a branch point from which more than two descendant taxa emerge. A ___ indicates that the evolutionary relationships among the descendant taxa are not yet clear.
Term
analogy
Definition
Similarity between two species that is due to convergent evolution rather than to descent from a common ancestor with the same trait
Term
homoplasy
Definition
Similar (analogous) structure or molecular sequence that has evolved independently in two species.
Term
molecular systematics
Definition
A scientific discipline that uses nucleic acids or other molecules in different species to infer evolutionary relationships
Term
cladistics
Definition
an approach to systematics in which organisms are placed into groups called clades based primarily on common descent
Term
clade
Definition
a group of species that includes an ancestral species and all its descendants
Term
monophyletic
Definition
pertaining to a group of taxa that consists of a common ancestor and all its descendants. A ___ taxon is equivalent to a clade
Term
paraphyletic
Definition
pertaining to a group of taxa that consists of a common ancestor and some, but not all, of its descendants
Term
polyphyletic
Definition
pertaining to a group of taxa derived from two or more different ancestors.
Term
shared ancestral character
Definition
a character, shared by members of a particular clade, that originated in an ancestor that is not a member of that clade.
Term
shared derived character
Definition
An evolutionary novelty that is unique to a particular clade
Term
outgroup
Definition
A species or group of species from an evolutionary lineage that is known to have diverged before the lineage that contains the group of species being studied. An ___ is selected so that its members are closely related to the group of species being studied, but not as closely related as any study-group members are to each other
Term
ingroup
Definition
A species or group of species whose evolutionary relationships we seek to determine
Term
maximum parsimony
Definition
a principle that states that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts
Term
maximum likelihood
Definition
as applied to systematics, a principle that states that when considering multiple phylogenetic hypothesis, one should take into account the hypothesis that reflects the most likely sequence of evolutionary events, given certain rules about how DNA changes over time
Term
phylogenetic bracketing
Definition
an approach in which features shared by two groups of organisms are predicted (by parsimony) to be present in their common ancestor and all of its descendants.
Term
orthologous genes
Definition
homologous genes that are found in different species because of speciation
Term
paralogous genes
Definition
homologous genes that are found in the same genome as a result of gene duplication.
Term
molecular clock
Definition
A method for estimating the time required for a given amount of evolutionary change, based on the observation that some regions of genomes appear to evolve at constant rates
Term
neutral theory
Definition
The hypothesis that much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by Darwinian natural selection
Term
horizontal gene transfer
Definition
the transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms
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