6
Genus- and species-level designations given here are those presented by Eschmeyer (2009:
E-13). Again, there have been many suggested changes to fi sh taxonomy at this level as well. For
fi
example, in European cyprinid fishes, many species previously placed in
fi
Leuciscus are now in the
genera Squalius, Telestes, and Petroleuciscus, and many species previously placed in Chondrostoma are now in the genera Protochondrostoma, Pseudochondrostoma, Parachondrostoma, Achondrostoma, and Iberochondrostoma (Kottelat and Freyhof 2007: K-130). Changes such as these are
noted in the karyotype database (Tables 4–7).
Historical Transition of Numbers of Karyotyped Species/Subspecies
The number of karyotyped species/subspecies has increased rapidly since the early 1970s. For
example, in 1973 karyotypes were available for 481 species/subspecies; in 1985, 1,318 species/
subspecies had been karyotyped; and at the time of this writing, data exist for 3,425 species/subspecies (see Table 1). Since the last compendium in 1995 (K-114), the number of karyotyped taxa
in Elasmobranchii, Chondrostei, and Teleostei increased but that in Petromyzontida, Holocephali,
Cladistia, and Holostei did not increase. In some cases, an increase in the number of karyotyped
taxa in Elasmobranchii and Teleostei has been caused by the erection of numerous additional taxa
and through revised techniques for chromosome preparation (Klinkhardt 1991: K-79).
Relationship Between Karyotype and Genome Size
Relationships between karyotypes and genome size in families were also explored (see Tables 2,
3). Sources of karyotypes and genome size were usually different. Data of karyotypes and genome
size were extracted from Tables 4–7 and the up-to-date list of Gregory (www.genomesize.com,
G-85).
As with karyotype data, there are signifi cant gaps in the fi
fi
sh genome size dataset.
fi
Two orders (Echinorhiniformes and Pristiophoriformes) and 21 families in cartilaginous fishes fi
and eight orders (Alubuliformes, Saccopharyngiformes, Gonorynciformes, Ateleopodiformes,
Lampriformes, Polymixiiformes, Percopsiformes, and Stephanoberyciformes) and 230 families in
actinopterygian fi shes have no information on genome size. Two orders (Echinorhiniformes and
fi
Pristiophoriformes) and 19 families in cartilaginous fishes and fi
fi
ve orders (Albuliformes, Saccofi
pharyngiformes, Ateleopodiformes, Lampriformes, Polymixiiformes) and 181 families in actinopterygian fi shes have neither information on karyotypes nor information on genome size.
fi
As for jawless fi shes, karyotypes and genome size in the Myxiniformes differ from those in the
fi
Petromyzontiformes, i.e., 2n ≤ 36 and genome size >5.0 pg/cell in Myxiniformes versus 2n = 76
or >140 and genome size <4.3 pg/cell in Petromyzontiformes. Myxiniformes exhibits different
chromosome numbers and DNA amounts between somatic cells and spermatogonia, i.e., 2n =
14–36 in somatic cells versus 2n = 16–96 in spermatogonia. B chromosomes have been reported
in spermatogonia in Myxiniformes (Nakai et al. 1995: N-62; Kojima et al. 2010: K-140).
As for jawed fi shes, diploid chromosome numbers and genome size in cartilaginous fi
fi
shes
fi
except Chimaeriformes are larger than those in actinopterygian fishes. The Polypteriformes and
fi
the Coelacanthiformes possess about 7.0–9.0 pg/cell. The Ceratodontiformes has extraordinary
large genome sizes (more than 80.0 pg/cell).
Acipenseriformes is of special interest among Actinopterygii in their possession of 105 to 372
chromosomes and 2.4 to 13.8 pg/cell. Ploidy levels including diploidy (2X), tetraploidy (4X), and
hexaploidy (6X) have been inferred in this order. However, the high number of chromosomes
suggests another possible series, i.e., tetraploidy, octaploidy, and dodecaploidy (Fontana et al. 2007:
F-61).
Genus- and species-level designations given here are those presented by Eschmeyer (2009:
E-13). Again, there have been many suggested changes to fi sh taxonomy at this level as well. For
fi
example, in European cyprinid fishes, many species previously placed in
fi
Leuciscus are now in the
genera Squalius, Telestes, and Petroleuciscus, and many species previously placed in Chondrostoma are now in the genera Protochondrostoma, Pseudochondrostoma, Parachondrostoma, Achondrostoma, and Iberochondrostoma (Kottelat and Freyhof 2007: K-130). Changes such as these are
noted in the karyotype database (Tables 4–7).
Historical Transition of Numbers of Karyotyped Species/Subspecies
The number of karyotyped species/subspecies has increased rapidly since the early 1970s. For
example, in 1973 karyotypes were available for 481 species/subspecies; in 1985, 1,318 species/
subspecies had been karyotyped; and at the time of this writing, data exist for 3,425 species/subspecies (see Table 1). Since the last compendium in 1995 (K-114), the number of karyotyped taxa
in Elasmobranchii, Chondrostei, and Teleostei increased but that in Petromyzontida, Holocephali,
Cladistia, and Holostei did not increase. In some cases, an increase in the number of karyotyped
taxa in Elasmobranchii and Teleostei has been caused by the erection of numerous additional taxa
and through revised techniques for chromosome preparation (Klinkhardt 1991: K-79).
Relationship Between Karyotype and Genome Size
Relationships between karyotypes and genome size in families were also explored (see Tables 2,
3). Sources of karyotypes and genome size were usually different. Data of karyotypes and genome
size were extracted from Tables 4–7 and the up-to-date list of Gregory (www.genomesize.com,
G-85).
As with karyotype data, there are signifi cant gaps in the fi
fi
sh genome size dataset.
fi
Two orders (Echinorhiniformes and Pristiophoriformes) and 21 families in cartilaginous fishes fi
and eight orders (Alubuliformes, Saccopharyngiformes, Gonorynciformes, Ateleopodiformes,
Lampriformes, Polymixiiformes, Percopsiformes, and Stephanoberyciformes) and 230 families in
actinopterygian fi shes have no information on genome size. Two orders (Echinorhiniformes and
fi
Pristiophoriformes) and 19 families in cartilaginous fishes and fi
fi
ve orders (Albuliformes, Saccofi
pharyngiformes, Ateleopodiformes, Lampriformes, Polymixiiformes) and 181 families in actinopterygian fi shes have neither information on karyotypes nor information on genome size.
fi
As for jawless fi shes, karyotypes and genome size in the Myxiniformes differ from those in the
fi
Petromyzontiformes, i.e., 2n ≤ 36 and genome size >5.0 pg/cell in Myxiniformes versus 2n = 76
or >140 and genome size <4.3 pg/cell in Petromyzontiformes. Myxiniformes exhibits different
chromosome numbers and DNA amounts between somatic cells and spermatogonia, i.e., 2n =
14–36 in somatic cells versus 2n = 16–96 in spermatogonia. B chromosomes have been reported
in spermatogonia in Myxiniformes (Nakai et al. 1995: N-62; Kojima et al. 2010: K-140).
As for jawed fi shes, diploid chromosome numbers and genome size in cartilaginous fi
fi
shes
fi
except Chimaeriformes are larger than those in actinopterygian fishes. The Polypteriformes and
fi
the Coelacanthiformes possess about 7.0–9.0 pg/cell. The Ceratodontiformes has extraordinary
large genome sizes (more than 80.0 pg/cell).
Acipenseriformes is of special interest among Actinopterygii in their possession of 105 to 372
chromosomes and 2.4 to 13.8 pg/cell. Ploidy levels including diploidy (2X), tetraploidy (4X), and
hexaploidy (6X) have been inferred in this order. However, the high number of chromosomes
suggests another possible series, i.e., tetraploidy, octaploidy, and dodecaploidy (Fontana et al. 2007:
F-61).