Species-specific SNP arrays for non-invasive genetic monitoring of a vulnerable bat.

Genetic tagging from scats is one of the minimally invasive sampling (MIS) monitoring approaches commonly used to guide management decisions and evaluate conservation efforts. Microsatellite markers have traditionally been used but are prone to genotyping errors. Here, we present a novel method for individual identification in the Threatened ghost bat Macroderma gigas using custom-designed Single Nucleotide Polymorphism (SNP) arrays on the MassARRAY system. We identified 611 informative SNPs from DArTseq data from which three SNP panels (44-50 SNPs per panel) were designed. We applied SNP genotyping and molecular sexing to 209 M. gigas scats collected from seven caves in the Pilbara, Western Australia, employing a two-step genotyping protocol and identifying unique genotypes using a custom-made R package, ScatMatch. Following data cleaning, the average amplification rate was 0.90 ± 0.01 and SNP genotyping errors were low (allelic dropout 0.003 ± 0.000) allowing clustering of scats based on one or fewer allelic mismatches. We identified 19 unique bats (9 confirmed/likely males and 10 confirmed/likely females) from a maternity and multiple transitory roosts, with two male bats detected using roosts, 9 km and 47 m apart. The accuracy of our SNP panels enabled a high level of confidence in the identification of individual bats. Targeted SNP genotyping is a valuable tool for monitoring and tracking of non-model species through a minimally invasive sampling approach.

Development and optimisation of molecular assays for microsatellite genotyping and molecular sexing of non-invasive samples of the ghost bat, Macroderma gigas.

The ghost bat (Macroderma gigas) is endemic to Australia but is under threat, with scarce information available on the genetic health of remaining populations. Here, we develop molecular assays for microsatellite genotyping and molecular sexing of non-invasive samples as a genetic monitoring tool to identify individuals, measure genetic diversity and investigate spatial and temporal patterns of habitat use by ghost bats. We identified novel microsatellites through high-throughput sequencing on the Illumina MiSeq platform. Of 48 loci tested, six markers were added to five previously developed microsatellite loci. We developed three Y-linked (DDX3Y, Zfy and SRY) and one X-linked markers (Zfx) to enable molecular identification of sex. To assess performance, all 11 microsatellite and four sex-linked markers were amplified in three multiplex reactions in 160 M. gigas faecal samples from the Pilbara region, Western Australia. The combined markers offered a high level of individual discrimination (PIDsibs = 0.00002) and we detected 19 bats in total (11 males, 4 females and 4 sex undetermined). The number of alleles per locus ranged from 5 to 14 and the average observed and expected heterozygosity across loci were Ho = 0.735 (0.58-0.91) and uHe = 0.785 (0.59-0.89) respectively. Our molecular assays allowed identification of individuals from faecal samples at multiple time points and spatial locations and enabled us to elucidate patterns of habitat usage at the study site. This study highlights the value of our molecular assays as a potential capture-mark-recapture technique for population monitoring for this species.