Chapter 18: classification and systematics

21 terms by nicole191 

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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.

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