Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun In a cladogram, a point from which two or more new branches diverge, representing either of two cases.
  • noun A multiple speciation event in which two or more species diverge from the same ancestor.
  • noun A speciation event in which two or more species are presumed to descend from the same ancestor, but the order of speciation is unknown.

from The Century Dictionary.

  • noun Division into more than two parts: distinguished from dichotomy.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Logic) A division into many members.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun taxonomy A section of a phylogeny in which the evolutionary relationships can not be fully resolved to dichotomies

Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[poly– + –tomy (on the model of dichotomy).]

Examples

  • In a phylogenetic tree, a polytomy is represented as a node which has more than two immediate descending branches.

    A Disclaimer for Behe?

  • Wrong - a polytomy is not that cladistics can only have two branches from any particular node.

    A Disclaimer for Behe?

  • This is called a polytomy, as opposed to a dichotomy.

    A Disclaimer for Behe?

  • This is called a polytomy, as opposed to a dichotomy.

    A Disclaimer for Behe?

  • But anyway this (polytomy) proves my point that cladistics assumes common ancestry by way of shared characteristics

    A Disclaimer for Behe?

  • ID guy: But anyway this (polytomy) proves my point that cladistics assumes common ancestry by way of shared characteristics

    A Disclaimer for Behe?

  • Polytomy: A polytomy (also called a polychotomy) is a section of a phylogeny in which the evolutionary relationships can not be fully resolved to dichotomies.

    A Disclaimer for Behe?

  • In nomenclatorial terms, the taxa in a soft polytomy belong to a clade, but are 'incertae sedis' within that clade.

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  • Y. padellus and Y. cagnagellus as a clade in a polytomy with our

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  • The only polytomy on the majority-rule consensus tree is an almost basal one between

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