Chapter 26 Flashcards
the evolutionary history of a species or group of related species.
phylogeny
a scientific discipline focused on classifying organisms and determining their evolutionary relationships.
systematics
a scientific discipline concerned with naming and classifying the diverse forms of life.
taxonomy
the two-part latinized name of a species, consisting of the genus and specific epithet.
binomial
a branching diagram that represents a hypothesis about the evolutionary history of a group of organisms.
phylogenetic tree
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.
branch points
system of classification of organisms based on evolutionary relationships. Only groups that include a common ancestor and all of its descendants are named.
PhyloCode
groups of organisms that share an immediate common ancestor and hence each other’s closest relatives.
sister taxa
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.
polytomy
similarity between two species that is due to convergent evolution rather than to descent from a common ancestor with the same trait.
analogy
similar (analogous) structure or molecular sequence that has evolved independently in two species.
homoplasy
a scientific discipline that uses nucleic acids or other molecules in different species to infer evolutionary relationships.
molecular systematics
an approach to systematics in which organisms are placed into groups called clades based primarily on common descent.
cladistics
A group of species that includes an ancestral species and all its descendants.
clades
Pertaining to a group of taxa that consists of a common ancestor and all its descendants. A _____ taxon is equivalent to a clade.
monophyletic
pertaining to a group of taxa that consists of a common ancestor and some, but not all, of its descendants.
paraphyletic
a character, shared by members of a particular clade, that originated in an ancestor that is not a member of that clade.
shared ancestral character
an evolutionary novelty that is unique to a particular clade.
shared derived character
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. A(n) _______ 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.
outgroup
a species or group of species whose evolutionary relationships we seek to determine.
ingroup
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.
maximum parsimony
as applied to systematics, a principle that states that when considering multiple phylogenetic hypotheses, 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.
maximum likelihood
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.
phylogenetic bracketing
homologous genes that are found in different species because of speciation.
orthologous genes
homologous genes that are found in the same genome as a result of gene duplication.
paralogous genes
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.
molecular clock
the hypothesis that much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by Darwinian natural selection.
neutral theory
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.
horizontal gene transfer
