J Syst Evol ›› 2008, Vol. 46 ›› Issue (3): 424-438.DOI: 10.3724/SP.J.1002.2008.08062

• Research Articles • Previous Articles    

Inferring the Tree of Life of the order Cypriniformes, the earth's most diverse clade of freshwater fishes: Implications of varied taxon and character sampling

1Richard L. MAYDEN*, 1Kevin L. TANG, 1Robert M. WOOD, 1Wei-Jen CHEN, 1Mary K. AGNEW, 1Kevin W. CONWAY, 1Lei YANG, 2Andrew M. SIMONS, 3Henry L. BART, 4Phillip M.HARRIS, 5Junbing LI, 5Xuzhen WANG, 6Kenji SAITOH, 5Shunping HE, 5Huanzhang LIU, 5Yiyu CHEN, 7Mutsumi NISHIDA, 8Masaki MIYA   

  1. 1(Department of Biology, Saint Louis University, St. Louis, MO 63103, USA)

    2(Department of Fisheries, Wildlife, and Conservation Biology, Bell Museum of Natural History, University of Minnesota, St. Paul, MN 55108, USA)

    3(Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA 70118, USA)

    4(Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA)

    5(Laboratory of Fish Phylogenetics and Biogeography, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China)

    6(Tohoku National Fisheries Research Institute, Fisheries Research Agency, Miyagi 985-0001, Japan)

    7(Ocean Research Institute, University of Tokyo, Tokyo 164-8639, Japan)

    8(Department of Zoology, Natural History Museum & Institute, Chiba 260-8682, Japan)
  • Received:2008-04-28 Published:2008-05-18

Abstract: The phylogenetic relationships of species are fundamental to any biological investigation, including all evolutionary studies. Accurate inferences of sister group relationships provide the researcher with an historical framework within which the attributes or geographic origin of species (or supraspecific groups) evolved. Taken out of this phylogenetic context, interpretations of evolutionary processes or origins, geographic distributions, or speciation rates and mechanisms, are subject to nothing less than a biological experiment without controls. Cypriniformes is the most diverse clade of freshwater fishes with estimates of diversity of nearly 3,500 species. These fishes display an amazing array of morphological, ecological, behavioral, and geographic diversity and offer a tremendous opportunity to enhance our understanding of the biotic and abiotic factors associated with diversification and adaptation to environments. Given the nearly global distribution of these fishes, they serve as an important model group for a plethora of biological investigations, including indicator species for future cli-matic changes. The occurrence of the zebrafish, Danio rerio, in this order makes this clade a critical component in understanding and predicting the relationship between mutagenesis and phenotypic expressions in vertebrates, including humans. With the tremendous diversity in Cypriniformes, our understanding of their phylogenetic relationships has not proceeded at an acceptable rate, despite a plethora of morphological and more recent mo-lecular studies. Most studies are pre-Hennigian in origin or include relatively small numbers of taxa. Given that analyses of small numbers of taxa for molecular characters can be compromised by peculiarities of long-branch attraction and nodal-density effect, it is critical that significant progress in our understanding of the relationships of these important fishes occurs with increasing sampling of species to mitigate these potential problems. The recent Cypriniformes Tree of Life initiative is an effort to achieve this goal with morphological and molecular (mitochondrial and nuclear) data. In this early synthesis of our understanding of the phylogenetic relationships of these fishes, all types of data have contributed historically to improving our understanding, but not all analyses are complementary in taxon sampling, thus precluding direct understanding of the impact of taxon sampling on achieving accurate phylogenetic inferences. However, recent molecular studies do provide some insight and in some instances taxon sampling can be implicated as a variable that can influence sister group relationships. Other instances may also exist but without inclusion of more taxa for both mitochondrial and nuclear genes, one cannot distinguish between inferences being dictated by taxon sampling or the origins of the molecular data.

Key words: Cobitoidea, Cypriniformes, Cyprinoidea, taxon sampling, Tree of Life