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21 terms

Chapter 18: classification and systematics

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Analogous features
features that resemb;e eachother but are not based on homologous genes, those related by descent from common ancestral genes
Apomorphy
a feature present in one (autopomorphy) or several (synopomorphy) derived members of a group but is not present in the ancestral members
Artificial classification system
a classification not based on evolutionary, phylogenetic relationships, but on other characters
Basal angiosperms
the several clades of angiosperms that arose before the rest of the angiosperms diverged into the monocots and eudicots
Binomial system of nomenclature
: a system providing scientific names to organisms, each name consists of the genous name and the speciec epithet
Cladogram
a branching diagram sowing the phylogenetic relationships of several or many taxa
Common ancestor
during divergent evolutiona common ancstor gives rise to two or more groups, in a cladogram, it is node that gives rise to the taxa being studied
Eudicots
the clade of angiosperms that contains most species formally known as dicots, broad leaves and pollen with more than one germination pore
Form genus
genus based on a character that is not a reliable indicator of evolutionary relationships, unrelated groups get grouped together
Homologous features
features that are the phenotypic expression of homologous genes, those related by descent from common ancestoral genes
Inheritance of acquired characteristics
the first law of mendelian genetics
Natural system of classification
classification based on evolutionary, phylogenetic relationships
Nomenclature
where a common ancestor is located on a cladogram
Parsimony
the concept of minimum complexity: the simplest hypothesis that explains several observation is the most parsimonious. In cladistics, a cladogram with the least number of steps is the most parsimonious
Phylogeny
the evolutionary relationships where one taxon evolves into others that evolve into still more
Paraphyletic group
: a clade that contains an ancestral taxon, and several but not all its descendants
Scientific names
the binomial name of a species
Species
: a group of organisms that can interbreed and produce fertile offspring
Taxon
a term that refers to any taxonomic group such as species, genus, family, etc...
Type specimen: a single specimen that is the absolute standard for the species and its scientific name
symplesiomorphy
a trait which is shared (a symmorphy) between two or more taxa, but which is also shared with other taxa which have an earlier last common ancestor with the taxa under consideration
synapomorphy
a trait that is shared ("symmorphy") by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait.