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Evolution of miniaturization and the phylogenetic position of Paedocypris, comprising the world's smallest vertebrate.
BMC Evol Biol. 2007 Mar 13; 7:38.BE

Abstract

BACKGROUND

Paedocypris, a highly developmentally truncated fish from peat swamp forests in Southeast Asia, comprises the world's smallest vertebrate. Although clearly a cyprinid fish, a hypothesis about its phylogenetic position among the subfamilies of this largest teleost family, with over 2400 species, does not exist. Here we present a phylogenetic analyses of 227 cypriniform taxa, including 213 cyprinids, based upon complete mitochondrial DNA cytochrome b nucleotide sequences in order to determine the phylogenetic position of Paedocypris and to study the evolution of miniaturization among cyprinids.

RESULTS

Our analyses reveal a strongly supported sister group relationship (clade C) between Paedocypris and Sundadanio, another developmentally truncated miniature cyprinid. Clade C was resolved as sister group of a larger clade characterized by small rasborine taxa (clade D). We found that miniaturised taxa are more numerous in the rasborine clade A, formed by clades C and D, than in any other cyprinid clade. The consensus cytb in cyprinids includes 380 amino acids and an incomplete T-- stop codon. We noted that a few cyprinids mostly rasborine taxa placed within clade A had either a TAA or TAG stop codon, 376, 378, or 381 amino acids, and up to 10 base pairs (bp) of noncoding region before the 5' end of the tRNA-Thr. Our relaxed molecular clock estimates revealed high divergence times for the Sundadanio and Paedocypris clades and provide a first temporal framework for the evolution of miniaturization among cyprinids.

CONCLUSION

Paedocypris belongs to a clade (Rasborinae clade A) that shows recurrent miniaturization, including both taxa characterized by developmental truncation and by proportioned dwarfism. Its closest relative is another miniaturized taxon, the genus Sundadanio. We conclude that the miniaturized cyprinids with remarkable morphological novelties, like Paedocypris and Danionella, are at the same time the most developmentally truncated taxa. The miniaturized cyprinids with no or few developmental truncations like Boraras, Microrasbora, and Horadandia show no such evolutionary novelties.

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Authors+Show Affiliations

Rüber L
Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK. l.ruber@nhm.ac.uk
Kottelat M
No affiliation info available
Tan HH
No affiliation info available
Ng PK
No affiliation info available
Britz R
No affiliation info available

MeSH

AnimalsBase SequenceBody SizeCyprinidaeCytochromes bDNA PrimersEvolution, MolecularGenetic VariationMolecular Sequence DataPhylogenySequence Alignment

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17355618

Citation

Rüber, Lukas, et al. "Evolution of Miniaturization and the Phylogenetic Position of Paedocypris, Comprising the World's Smallest Vertebrate." BMC Evolutionary Biology, vol. 7, 2007, p. 38.
Rüber L, Kottelat M, Tan HH, et al. Evolution of miniaturization and the phylogenetic position of Paedocypris, comprising the world's smallest vertebrate. BMC Evol Biol. 2007;7:38.
Rüber, L., Kottelat, M., Tan, H. H., Ng, P. K., & Britz, R. (2007). Evolution of miniaturization and the phylogenetic position of Paedocypris, comprising the world's smallest vertebrate. BMC Evolutionary Biology, 7, 38.
Rüber L, et al. Evolution of Miniaturization and the Phylogenetic Position of Paedocypris, Comprising the World's Smallest Vertebrate. BMC Evol Biol. 2007 Mar 13;7:38. PubMed PMID: 17355618.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Evolution of miniaturization and the phylogenetic position of Paedocypris, comprising the world's smallest vertebrate. AU - Rüber,Lukas, AU - Kottelat,Maurice, AU - Tan,Heok Hui, AU - Ng,Peter K L, AU - Britz,Ralf, Y1 - 2007/03/13/ PY - 2006/10/23/received PY - 2007/03/13/accepted PY - 2007/3/16/pubmed PY - 2007/4/10/medline PY - 2007/3/16/entrez SP - 38 EP - 38 JF - BMC evolutionary biology JO - BMC Evol Biol VL - 7 N2 - BACKGROUND: Paedocypris, a highly developmentally truncated fish from peat swamp forests in Southeast Asia, comprises the world's smallest vertebrate. Although clearly a cyprinid fish, a hypothesis about its phylogenetic position among the subfamilies of this largest teleost family, with over 2400 species, does not exist. Here we present a phylogenetic analyses of 227 cypriniform taxa, including 213 cyprinids, based upon complete mitochondrial DNA cytochrome b nucleotide sequences in order to determine the phylogenetic position of Paedocypris and to study the evolution of miniaturization among cyprinids. RESULTS: Our analyses reveal a strongly supported sister group relationship (clade C) between Paedocypris and Sundadanio, another developmentally truncated miniature cyprinid. Clade C was resolved as sister group of a larger clade characterized by small rasborine taxa (clade D). We found that miniaturised taxa are more numerous in the rasborine clade A, formed by clades C and D, than in any other cyprinid clade. The consensus cytb in cyprinids includes 380 amino acids and an incomplete T-- stop codon. We noted that a few cyprinids mostly rasborine taxa placed within clade A had either a TAA or TAG stop codon, 376, 378, or 381 amino acids, and up to 10 base pairs (bp) of noncoding region before the 5' end of the tRNA-Thr. Our relaxed molecular clock estimates revealed high divergence times for the Sundadanio and Paedocypris clades and provide a first temporal framework for the evolution of miniaturization among cyprinids. CONCLUSION: Paedocypris belongs to a clade (Rasborinae clade A) that shows recurrent miniaturization, including both taxa characterized by developmental truncation and by proportioned dwarfism. Its closest relative is another miniaturized taxon, the genus Sundadanio. We conclude that the miniaturized cyprinids with remarkable morphological novelties, like Paedocypris and Danionella, are at the same time the most developmentally truncated taxa. The miniaturized cyprinids with no or few developmental truncations like Boraras, Microrasbora, and Horadandia show no such evolutionary novelties. SN - 1471-2148 UR - https://www.unboundmedicine.com/medline/citation/17355618/Evolution_of_miniaturization_and_the_phylogenetic_position_of_Paedocypris_comprising_the_world's_smallest_vertebrate_ L2 - https://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-7-38 DB - PRIME DP - Unbound Medicine ER -