Characterization of 17 novel microsatellite loci in the Nile monitor (Varanus niloticus) via 454 pyrosequencing

We used 454 pyrosequencing to characterize 17 novel microsatellite loci from the Nile monitor (Varanus niloticus), using samples from an invasive population in the US state of Florida. These markers were screened for variation in 40 individuals from the City of Cape Coral. Observed heterozygosity ranged from 0.18 to 0.73 (mean ± SE = 0.46 ± 0.06) and the number of alleles per locus ranged from 1 to 4 (mean ± SE = 2.5 ± 0.2). Preliminary genotyping of samples from populations in West Palm Beach and Homestead revealed two loci (Mon6 and Mon15) that are monomorphic in Cape Coral, but polymorphic in these other two populations. We found no statistical departures from Hardy-Weinberg equilibrium or evidence of null alleles. However, there was statistical evidence for genotypic disequilibrium between Mon1-Mon14 and Mon3-Mon8. BLASTn searches of NCBI’s nr/nt database identified four microsatellites containing 454 fragments that exhibit substantial sequence similarity to loci in other reptilian genomes, suggesting these markers should be prioritized by researchers interested in cross-amplification in other varanids. The resources we have developed will enable investigations of the population genetic dynamics of invasive Nile monitors in Florida and may facilitate studies within this species native range.