7
Diploid chromosome numbers and genome size in Neopterygii except the Lepisosteiformes,
Osteoglossiformes, Characiformes, Siluriformes, Osmeriformes, and Salmoniformes are usually
48 or 50 and lower than 3.0 pg/cell, respectively. However, more than 3.0 pg/cell in Neopterygii
has been reported in Anguilliformes, Cypriniformes, Characiformes, Siluriformes, Argentiniformes, Esociformes, Myctophiformes, Gasterosteiformes, Batrachoidiformes, Synbranchiformes,
and Perciformes, i.e., Muraenidae, Cyprinidae (Cyprininae, part of Gobioninae, part of Leuciscinae,
part of Rasborinae, Schizothoracinae, and polyploid species in Barbinae), polyploid species of
Cobitidae, Catostomidae, part of Characidae, Curimatidae, Prochilodontidae, Ariidae, part of Callichthyidae, Doradidae, part of Loricariidae, Plotosidae, Microstomatidae, part of Umbridae, Myctophidae, part of Syngnathidae, Batrachoididae, part of Synbranchidae, Scaridae, Artedidraconidae,
and Channichthyidae.
Among taxa described above, freshwater fishes such as part of Cypriniformes (Catostomidae,
fi
part of Cyprinidae, part of Cobitidae), and part of Siluriformes (part of Callichthyidae) may be of
polyploid origin (Allendorf and Thorgaard 1984: A-16; Ferris 1984: F-23).
Complex relationships between ploidy and genome size have been reported in the Cobitoidea.
In one example, the Leptobotiinae-Balitoridae exhibit 2n = 48–50 and genome size about 1.0 pg/
cell, whereas the Botiinae possess 2n = 98–100 and genome size about 2.0 pg/cell. A second
example is provided by comparing Cobitis species with 2n = 48–50 and about 4.0 pg/cell versus
those with 2n = 96–100 and about 7.0 pg/cell. A third example comes from non-Cobitis cobitids
with 2n = 48–50 with about 2.0 pg/cell versus those with 2n = 96–100 and about 4.5 pg/cell (Suzuki
1996: S-143).
The diploid chromosome number in marine neopterygian fi shes, which have various genome
fi
sizes (0.8–4.4 pg/cell), was generally 46, 48, or 50 with the exception of 2n = 56 in Osmeriformes
and did not show polyploidy, although triploidy was exceptionally reported in the Zoarcidae (Perciformes) (Morescalchi et al. 1996: M-89). In other words, it is diffi cult to infer polyploidy in marine
fi
fishes from genome size.
fi
In Teleostei, genome size is relatively conserved in families, with the important exception of
those including recent or ancient polyploids. Diploid chromosome numbers have been thought
to vary across taxa above the family level, but when they were analyzed in terms of Robertsonian
translocation and tandem fusion, they were found to be more conservative in each family. On the
other hand, there are several problems in karyological analysis. The fi nding of B chromosomes
fi
might cause change of 2n, NF, and ancestral chromosome number (ACN) in taxa that have been
reported to possess no B chromosomes. It is likely that many more species, when analyzed with
suffi cient intensity, will be found to possess B chromosomes (Camacho et al. 2000: C-2). B chrofi
mosomes have been studied actively in Characiformes and neotropical Siluriformes (Carvalho
et al. 2008: C-98), but there have been very few data on B chromosomes in the other taxa.
Diploid chromosome numbers and genome size in Neopterygii except the Lepisosteiformes,
Osteoglossiformes, Characiformes, Siluriformes, Osmeriformes, and Salmoniformes are usually
48 or 50 and lower than 3.0 pg/cell, respectively. However, more than 3.0 pg/cell in Neopterygii
has been reported in Anguilliformes, Cypriniformes, Characiformes, Siluriformes, Argentiniformes, Esociformes, Myctophiformes, Gasterosteiformes, Batrachoidiformes, Synbranchiformes,
and Perciformes, i.e., Muraenidae, Cyprinidae (Cyprininae, part of Gobioninae, part of Leuciscinae,
part of Rasborinae, Schizothoracinae, and polyploid species in Barbinae), polyploid species of
Cobitidae, Catostomidae, part of Characidae, Curimatidae, Prochilodontidae, Ariidae, part of Callichthyidae, Doradidae, part of Loricariidae, Plotosidae, Microstomatidae, part of Umbridae, Myctophidae, part of Syngnathidae, Batrachoididae, part of Synbranchidae, Scaridae, Artedidraconidae,
and Channichthyidae.
Among taxa described above, freshwater fishes such as part of Cypriniformes (Catostomidae,
fi
part of Cyprinidae, part of Cobitidae), and part of Siluriformes (part of Callichthyidae) may be of
polyploid origin (Allendorf and Thorgaard 1984: A-16; Ferris 1984: F-23).
Complex relationships between ploidy and genome size have been reported in the Cobitoidea.
In one example, the Leptobotiinae-Balitoridae exhibit 2n = 48–50 and genome size about 1.0 pg/
cell, whereas the Botiinae possess 2n = 98–100 and genome size about 2.0 pg/cell. A second
example is provided by comparing Cobitis species with 2n = 48–50 and about 4.0 pg/cell versus
those with 2n = 96–100 and about 7.0 pg/cell. A third example comes from non-Cobitis cobitids
with 2n = 48–50 with about 2.0 pg/cell versus those with 2n = 96–100 and about 4.5 pg/cell (Suzuki
1996: S-143).
The diploid chromosome number in marine neopterygian fi shes, which have various genome
fi
sizes (0.8–4.4 pg/cell), was generally 46, 48, or 50 with the exception of 2n = 56 in Osmeriformes
and did not show polyploidy, although triploidy was exceptionally reported in the Zoarcidae (Perciformes) (Morescalchi et al. 1996: M-89). In other words, it is diffi cult to infer polyploidy in marine
fi
fishes from genome size.
fi
In Teleostei, genome size is relatively conserved in families, with the important exception of
those including recent or ancient polyploids. Diploid chromosome numbers have been thought
to vary across taxa above the family level, but when they were analyzed in terms of Robertsonian
translocation and tandem fusion, they were found to be more conservative in each family. On the
other hand, there are several problems in karyological analysis. The fi nding of B chromosomes
fi
might cause change of 2n, NF, and ancestral chromosome number (ACN) in taxa that have been
reported to possess no B chromosomes. It is likely that many more species, when analyzed with
suffi cient intensity, will be found to possess B chromosomes (Camacho et al. 2000: C-2). B chrofi
mosomes have been studied actively in Characiformes and neotropical Siluriformes (Carvalho
et al. 2008: C-98), but there have been very few data on B chromosomes in the other taxa.