The two giant sister species of the Southern Ocean, Dissostichus eleginoides and Dissostichus mawsoni, differ in karyotype and chromosomal pattern of ribosomal RNA genes

The two giant notothenioid species, the Patagonian toothfish Dissostichus eleginoides and the Antarctic toothfish D. mawsoni, are important components of the Antarctic ichthyofauna and heavily exploited commercially. They have similar appearance and size, both are piscivorous and benthopelagic, but...

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Bibliographic Details
Published in:Polar Biology
Main Authors: GHIGLIOTTI, LAURA, PISANO, EVA, F. MAZZEI, C. OZOUF COSTAZ, C. BONILLO, R. WILLIAMS, C. H. CHENG
Other Authors: Ghigliotti, Laura, F., Mazzei, C., OZOUF COSTAZ, C., Bonillo, R., William, C. H., Cheng, Pisano, Eva
Format: Article in Journal/Newspaper
Language:English
Published: Springer Verlag 2007
Subjects:
Antarctic
Southern Ocean
The Antarctic
Antarc*
Antarctic Toothfish
Patagonian Toothfish
Online Access:http://hdl.handle.net/11567/224528
https://doi.org/10.1007/s00300-006-0222-6
Description
Summary:The two giant notothenioid species, the Patagonian toothfish Dissostichus eleginoides and the Antarctic toothfish D. mawsoni, are important components of the Antarctic ichthyofauna and heavily exploited commercially. They have similar appearance and size, both are piscivorous and benthopelagic, but differ in their geographic distribution and absence/presence of the antifreeze trait. We karyotyped these two sister species by analyzing specimens collected from multiple Antarctic and sub-Antarctic sites. Both species have a diploid number of 48, but differ in karyotypic formula, (2m + 2sm + 44a) for D. eleginoides and (2m + 4sm + 42a) for D. mawsoni, due to an extra pair of submetacentric chromosomes in the latter. Chromosomal fuorescence in situ hybridization with rDNA probes revealed unexpected species-specific organization of rRNA genes; D. mawsoni possesses two rDNA loci (versus one locus in D. eleginoides), with the second locus mapping to its additional submetacentric chromosome. The additional rRNA genes in D. mawsoni may be a cold-adaptive compensatory mechanism for growth and development of this large species in freezing seawater.

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