Key Terms – Organization of Life

analogous structure
a character found in two taxa that looks similar because of convergent evolution, not because of descent from a common ancestor
binomial nomenclature
a system of two-part scientific names for an organism, which includes genus and species names
branch point
a point on a phylogenetic tree where a single lineage splits to distinct new ones
clade
a group of taxa with the same set of shared derived characters, including an ancestral species and all its descendants
cladistics
a method used to organize homologous traits to describe phylogenies using common descendent as the primary criterion used to classify organisms
class
the category in the taxonomic classification system that falls within phylum and includes orders
domain
the highest level category in the classification system and that includes all taxonomic classifications below it; it is the most inclusive taxon
family
the category in the taxonomic classification system that falls within order and includes genera
genus
the category in the taxonomic classification system that falls within family and includes species; the first part of the scientific name
kingdom
the category in the taxonomic classification system that falls within domain and includes phyla
maximum parsimony
applying the simplest, most obvious way with the least number of steps
molecular systematics
the methods of using molecular evidence to identify phylogenetic relationships
monophyletic group
(also, clade) organisms that share a single ancestor
order
the category in the taxonomic classification system that falls within class and includes families
phylogenetic tree
diagram used to reflect the evolutionary relationships between organisms or groups of organisms
phylogeny
evolutionary history and relationship of an organism or group of organisms
phylum
the category in the taxonomic classification system that falls within kingdom and includes classes
rooted
describing a phylogenetic tree with a single ancestral lineage to which all organisms represented in the diagram relate
shared ancestral character
a character on a phylogenetic branch that is shared by a particular clade
shared derived character
a character on a phylogenetic tree that is shared only by a certain clade of organisms
sister taxa
two lineages that diverged from the same branch point
species
the most specific category of classification
systematics
the science of determining the evolutionary relationships of organisms
taxon
a single level in the taxonomic classification system
taxonomy
the science of classifying organisms

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Introduction to Living Systems Copyright © by Dr. Becki Brunelli. All Rights Reserved.