clade

(noun)

a group of animals or other organisms derived from a common ancestor species

Related Terms

Examples of clade in the following topics:

  • Building Phylogenetic Trees

    • Clades must include all of the descendants from a branch point.
    • Notice in the various examples of clades how each clade comes from a single point, whereas the non-clade groups show branches that do not share a single point .
    • All the organisms within a clade stem from a single point on the tree.
    • Thus, lizards, rabbits, and humans all belong to the clade Amniota.
    • Vertebrata is a larger clade that also includes fish and lamprey.

  • The Evolution of Craniata and Vertebrata

    • The clade Craniata is a subdivision of Chordata.
    • The clade Craniata includes all vertebrates and the hagfishes (Myxini), which have a cranium but lack a backbone.
    • Vertebrates are members of the subphylum Vertebrata, the clade Craniata, and the phylum Chordata.
    • Although it lacks a backbone, the hagfish is a member of the Craniata clade because it possesses a bony skull.
    • All vertebrates are in the Craniata clade and have a cranium.

  • Verrucomicrobia

    • Study of additional proteins from this proposed superphylum suggests that the Poribacteria may be separate from this clade.
    • The Planctomycetes may be basal to the Chlamydiae-Verrucomicrobia-Lentisphaerae clade.
    • Cavalier-Smith has postulated that the Verrucomicrobia belong in the clade Planctobacteria in the larger clade Gracilicutes. 16S rRNA data corroborate that view.

  • Gnathostomes: Jawed Fishes

    • Most modern gnathostomes belong to the clades Chondrichthyes and Osteichthyes.
    • This clade arose approximately 370 million years ago in the early or middle Devonian.
    • Members of the clade Osteichthyes, also called bony fish, are characterized by a bony skeleton.
    • Although most members of this clade are extinct, living members include the less-familiar lungfishes and coelacanths .
    • The (a) sockeye salmon (Actinopterygii) and (b) coelacanth (Sarcopterygii) are both bony fishes of the Osteichthyes clade.

  • Modern Reptiles

    • Class Reptilia includes many diverse species that are classified into four living clades.
    • Squamata is the largest extant clade of reptiles .
    • Turtles are members of the clade Testudines ("having a shell") .
    • The two clades of turtles are most easily recognized by how they retract their necks.
    • Turtles in the less speciose clade retract the neck with a horizontal curve.

  • Agnathans: Jawless Fishes

    • Hagfishes and lampreys are recognized as separate clades, primarily because lampreys are true vertebrates, whereas hagfishes are not.
    • The clade Myxini includes at least 20 species of hagfishes.
    • Since they have a cartilaginous skull, they are classified in the clade Craniata.
    • The clade Petromyzontidae includes approximately 35–40 or more species of lampreys.

  • Molecular Analyses and Modern Phylogenetic Trees

    • This discovery allowed for the distinction of the protostome clade: the lophotrochozoans.
    • Molecular research similar to the discoveries that brought about the distinction of the lophotrochozoan clade has also revealed a dramatic rearrangement of the relationships between mollusks, annelids, arthropods, and nematodes; a new ecdysozoan clade was formed.
    • However, molecular evidence has revealed that arthropods are actually more closely related to nematodes, now comprising the ecdysozoan clade, and annelids are more closely related to mollusks, brachiopods, and other phyla in the lophotrochozoan clade.
    • These two clades now make up the protostomes.

  • Planctomycetes

    • Cavalier-Smith has postulated that the Planctomycetes are within the clade Planctobacteria in the larger clade Gracilicutes.

  • Evolution of Amniotes

    • Clade Dinosauria includes birds, which evolved from a branch of dinosaurs.
    • Birds are descended, however, from dinosaurs, so this classical scheme results in groups that are not true clades.

  • Constructing an Animal Phylogenetic Tree

    • Eumetazoa are subdivided into radially-symmetrical animals and bilaterally-symmetrical animals and are classified into clade Radiata or Bilateria, respectively.
    • All other Eumetazoa are members of the Bilateria clade.
    • The bilaterally-symmetrical animals are further divided into deuterostomes (including chordates and echinoderms) and two distinct clades of protostomes (including ecdysozoans and lophotrochozoans).
    • Lophotrochozoa is named for two structural features, each common to certain phyla within the clade.