Karyotype diversity suggests that Laonastes aenigmamus (Laotian rock rat) (Rodentia, Diatomyidae) is a multi-specific genus
Laonastes aenigmamus (Khanyou) is a recently described rodent species living in geographically separated limestone formations of the Khammuan Province in Lao PDR. Chromosomes of 21 specimens of L. aenigmamus were studied using chromosome banding as well as fluorescent in situ hybridization (FISH) techniques using human painting, telomere repeats, and 28S rDNA probes. Four different karyotypes were established. Study with human chromosome paints and FISH revealed that four large chromosomes were formed by multiple common tandem fusions, with persistence of some interstitial telomeres. The rearrangements separating the different karyotypes (I to IV) were also reconstructed. Various combinations of Robertsonian translocations or tandem fusions involving the same chromosomes differentiate these karyotypes. These rearrangements create a strong gametic barrier, which isolates specimens with karyotype II from the others. C-banding and FISH with telomere repeats also exhibit large and systematized differences between karyotype II and others. These data indicate an ancient reproductive separation and suggest that Laonastes is not a mono-specific genus.
KeywordsLaonastes aenigmamus Chromosomes Rearrangements Gametic barrier
Fluorescent in situ hybridization
Muséum National d’Histoire Naturelle
Compliance with ethical standards
Since November 12, 2008, the conservation of L. aenigmamus is regulated in Lao PDR. This species was listed as « Endangered » on the IUCN Red List in January 12, 2009. To perform this study, we obtained an authorization (no. 1183 June 09, 2008) from the Lao Government. In December 2008, March 2009, and November 2009, 2010, and 2011, five sampling field trips took place in the Khammuan Province in collaboration with the Lao National Agriculture and Forestry Research Institute (NAFRI). The Khammuan Province Agriculture and Forestry Office (PAFO) validated our field collection schedule, and an officer escorted us. Almost all the specimens used for this study were dead animals, captured by traditional hunters. For the few animals captured by us, all institutional and national guidelines for the care and use of laboratory animals were followed, in agreement with the American Society of Mammalogists (Sikes and Gannon 2011).
Conflict of interest
All authors declare that they have no conflict of interest.
- Dutrillaux B, Couturier J (1981) La partique de l’analyse chromosomique. Ed Masson ParisGoogle Scholar
- Nicolas V, Herbreteau V, Couloux A, Keovichit K, Douangboupha B, Hugot JP (2012) A remarkable case of micro-endemism in Laonastes aenigmamus (Diatomyidae, Rodentia) revealed by nuclear and mitochondrial DNA sequence data. PLoS ONE 7(11):e48145. doi: 10.1371/journal.pone.0048145 CrossRefPubMedPubMedCentralGoogle Scholar
- Popescu P, Hayes H, Dutrillaux B (1998) Techniques de cytogénétique animale. Ed INRA Editions, ParisGoogle Scholar
- White MJD (1973) Animal cytology and evolution, 3rd edn. University Press, CambridgeGoogle Scholar