The western rainbowfish (Melanotaenia australis) is one of the most common and highly abundant freshwater fish endemic to north-western Australia. It shows extensive geographic variation in their colour pattern. Genetic study revealed spatial population structure in this species that could be a possible threat to its existence. Therefore we designed and isolated 15 highly polymorphic microsatellite markers for M. australis for use in population studies across its distribution. We screened these primers across 32 individuals from the Daly River and found between 4 and 22 alleles per locus. The observed heterozygosities ranged from 0.345 to 1.000. These markers will be now available for future studies of population structure across its natural range and to assist in management as well as future conservation.
The Australian lungfish is a primitive and endangered representative of the subclass Dipnoi. The distribution of this species is limited to south-east Queensland, with some populations considered endemic and others possibly descending from translocations in the late nineteenth century shortly after European discovery. Attempts to resolve the historical distribution for this species have met with conflicting results based on descriptive genetic studies. Understanding if all populations are endemic or some are the result of, or influenced by, translocation events, has implications for conservation management. In this work, we analysed the genetic variation at three types of markers (mtDNA genomes, 11 STRs, and 5,196 nuclear SNPs) using the Approximate Bayesian Computation algorithm to compare several demographic models. We postulated different contributions of Mary River and Burnett River gene pools into the Brisbane River and North Pine River populations, related to documented translocation events. We ran the analysis for each marker separately, and we also estimated the posterior probabilities of the models combining the markers. Nuclear SNPs have the highest power to correctly identify the true model amongst the simulated datasets (where the model was known), but different markers typically provided similar answers. The most supported demographic model able to explain the real dataset implies that an endemic gene pool is present in the Brisbane and North Pine Rivers where past translocations are documented. These results will inform ongoing conservation efforts for this endangered and iconic species and warrant careful consideration of future genetic management of the Australian lungfish populations.
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