Choanozoa

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Choanozoa
Temporal range: Neoproterozoic–Recent Molecular clock evidence for origin between 1050 and 800Ma[1]
Codonosiga
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Amorphea
Clade: Obazoa
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Clade: Choanozoa
Brunet and King, 2017
Subdivisions
Synonyms
  • Apoikozoa Budd & Jensen, 2015
  • Choanimal Fairclough et al., 2013

Choanozoa is a clade of opisthokont eukaryotes consisting of the choanoflagellates (Choanoflagellatea) and the animals (Animalia, Metazoa). The sister-group relationship between the choanoflagellates and animals has important implications for the origin of the animals.[2] The clade was identified in 2015 by Graham Budd and Sören Jensen, who used the name Apoikozoa.[3] The 2018 revision of the classification first proposed by the International Society of Protistologists in 2012 recommends the use of the name Choanozoa.[4]

Introduction

A close relationship between choanoflagellates and animals has long been

multicellularity found in animals.[citation needed
]

A synonym for the Choanozoa, Apoikozoa, derives from the ancient Greek for "colony" and "animal", referring to the ability of both animals and (some) choanoflagellates to form multicellular units.[4] While animals are permanently multicellular, the colony-building choanoflagellates are only sometimes so, which raises the question of whether or not the colony-building ability in both groups was present at the base of the entire clade, or whether it was independently derived within the animals and choanoflagellates.

Nomenclature

The name "Choanozoa" was first used by protozoologist

paraphyletic. Its classification was the following:[7]

The International Society of Protistologists rejected the use of this name for the paraphyletic group. Instead, since 2017, the name Choanozoa is considered appropriate for the clade that unites choanoflagellates and animals, since the

colonies, a characteristic not unique to this clade.[4]

Evolutionary implications

Although the last common ancestor of the Choanozoa cannot be reconstructed with certainty, Budd and Jensen suggest that these organisms formed benthic colonies that competed for space amongst other mat-forming organisms known to have existed during the

Ediacaran Period some 635–540 million years ago. As such they would form an important link between the unicellular ancestors of the animals and the enigmatic "Ediacaran" organisms known from this interval, thus allowing some sort of reconstruction of the earliest animals and their ecology.[3] In the following cladogram, an indication is given of approximately how many million years ago (Mya) the clades diverged into newer clades.[8][9][10] (Note that the later Budd and Jensen paper gives significantly younger dates. See also Kimberella.) The holomycota tree follows Tedersoo et al.[11]

Opisthokonta
Holomycota
Cristidiscoidea

Fonticulida

Nucleariida

Fungi
/

BCG2

True Fungi

Aphelida

BCG1

Rozellomyceta
/
Cryptomycota
Opisthosporidia
Holozoa

Ichthyosporea

Pluriformea

Syssomonas

Corallochytrium

Filozoa

Filasterea

Choanozoa

Choanoflagellatea

Animalia

950 mya
1100 mya
1300 mya

References

  1. Wikidata Q24614721
    .
  2. PMID 18273011
    .
  3. ^
    PMID 26588818
    .
  4. ^
    PMID 30257078
    .
  5. PMID 24337300
    .
  6. PMID 26621703
    .
  7. PMID 34940909
    .
  8. PMID 18192191
    .
  9. PMID 21810989
    .
  10. PMID 28648822
    .
  11. ISSN 1560-2745
    .
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