Low genetic diversity in nurseryfish, 'Kurtus gulliveri' (Perciformes: Kurtidae), and an appraisal of its breeding system using microsatellite loci

Abstract

The Nurseryfish, Kurtus gulliveri, is a freshwater fish distributed in northern Australia and southern New Guinea that exhibits forehead brooding, a unique form of male parental care. Microsatellite markers were developed for paternity analysis to study its reproductive life history in a population from the Adelaide River, Northern Territory, Australia. In 20 microsatellite loci tested, only two polymorphic markers were found. The microsatellite data are mostly consistent with the hypotheses that the putative egg-carrying male sired the egg mass and no multiple paternity occurred in the population examined. However, caution should be taken in interpreting the results, given the low genetic diversity and limited analytical power. The extremely low genetic diversity was also corroborated by mitochondrial DNA, the most variable fragment in the piscine mitogenome. Eighteen individuals from the Adelaide River were sequenced, revealing four polymorphic sites in the control region and five haplotypes in total, with an average p-distance of 0.001. Additional individuals from three other isolated populations in the Northern Territory (Daly River, South Alligator River and East Alligator River) were sequenced and found to be identical to one of the common haplotypes from the Adelaide River. Four specimens collected from New Guinea represent a single haplotype that had 24.5 substitutions, on average, relative to the Australian populations.