Improving cost-efficiency of faecal genotyping: New tools for elephant species

Next-Generation Snow Leopard Population Assessment Tool: Multiplex-PCR SNP Panel for Individual Identification From Faeces

In recent years, numerous single nucleotide polymorphism (SNP) panel methods to genotype non-invasive faecal samples have been developed. However, none of these existing methods fit all of the criteria necessary to make a SNP panel broadly usable for conservation projects in any country-cost effective, streamlined lab protocol and user-friendly open-source bioinformatics protocols for panel design and analysis. Here, we present such a method and display its utility by developing a multiplex PCR SNP panel for conducting individual ID of snow leopards, Panthera uncia, from faecal samples. The SNP panel we present consists of 144 SNPs and utilises next-generation sequencing technology. We validate our SNP panel with paired tissue and faecal samples from zoo individuals, showing a minimum of 96.7% accuracy in allele calls per run. We then generate SNP data from 235 field-collected faecal samples from across Pakistan to show that the panel can reliably identify individuals from low-quality faecal samples of unknown age and is robust to contamination. We also show that our SNP panel has the capability to identify first-order relatives among sampled zoo individuals and provides insights into the geographic origin of samples. This SNP panel will empower the snow leopard research community in their efforts to assess local and global snow leopard population sizes. More broadly, we present a SNP panel development method that can be used for any species of interest for which adequate genomic reference data is available.

Giants in the landscape: status, genetic diversity, habitat suitability and conservation implications for a fragmented Asian elephant (Elephas maximus) population in Cambodia

Asian elephant (Elephas maximus) populations are declining and increasingly fragmented across their range. In Cambodia, the Prey Lang Extended Landscape (PLEL) represents a vast expanse of lowland evergreen and semi-evergreen forest with potential to support Asian elephant population recovery in the country. To inform effective landscape-level conservation planning, this study provides the first robust population size estimate for Asian elephants in PLEL, based on non-invasive genetic sampling during the 2020-2021 dry season in three protected areas: Prey Lang, Preah Roka and Chhaeb Wildlife Sanctuaries. Further, it provides an assessment of the species' range, habitat suitability and connectivity within the landscape using Maxent and Fuzzy suitability models. Thirty-five unique genotypes (individual elephants) were identified, of which six were detected in both Preah Roka and Chhaeb Wildlife Sanctuaries, providing evidence that elephants move readily between these neighbouring protected areas. However, no unique genotypes were shared between Preah Roka/Chhaeb and the less functionally connected southerly Prey Lang Wildlife Sanctuary. The estimated population size in the southern population was 31 (95% CI [24-41]) individuals. The northern population of Preah Roka/Chhaeb Wildlife Sanctuaries is estimated to number 20 (95% CI [13-22]) individuals. Habitat loss is prevalent across the landscape and connectivity outside of the protected areas is very limited; however, large swathes of suitable elephant habitat remain. As the landscape holds the potential to be restored to a national stronghold for this flagship species, in turn resulting in the protection of a vast array of biodiversity, we recommend protection of remaining suitable habitat and reduction of threats and disturbance to elephants within these areas as top priorities. Our study offers a model for integrated elephant population and landscape-level habitat modelling that can serve to guide similar research and management efforts in other landscapes.

Advancements in noninvasive koala monitoring through combining Chlamydia detection with a targeted koala genotyping assay

Wildlife diseases are major players in local and global extinctions. Effective disease surveillance, management and conservation strategies require accurate estimates of pathogen prevalence. Yet pathogen detection in wild animals remains challenging. Current gold standards often require samples collected through veterinary examination, but this method is costly, intensive, invasive, and requires specialised staff and equipment. Collection of non-invasive samples, such as scats, is an effective monitoring tool which can be deployed at large scale, as scats contain DNA of both host and pathogens. The koala (Phascolarctos cinereus) is listed as 'endangered' under the EPBC Act 1999, with chlamydial disease representing a major threat. Here, we present a new approach that combines restriction-enzyme associated sequencing and targeted-sequence-capture genotyping, namely DArTcap, to detect Chlamydia pecorum in koala scats. We found this method has similar accuracy to current gold standards (qPCR of swab samples), with a sensitivity of 91.7% and a specificity of 100%. This method can be incorporated into existing koala genetic studies using marker panels, where population attributes can be estimated alongside C. pecorum presence, using the same scat samples, with the option to add further markers of interest. Such a one-stop-shop panel would considerably reduce processing times and cost.

A method for noninvasive individual genotyping of black-footed cat (Felis nigripes)

The black-footed cat (Felis nigripes) is endemic to the arid regions of southern Africa. One of the world's smallest wild felids, the species occurs at low densities and is secretive and elusive, which makes ecological studies difficult. Genetic data could provide key information such as estimates on population size, sex ratios, and genetic diversity. In this study, we test if microsatellite loci can be successfully amplified from scat samples that could be noninvasively collected from the field. Using 21 blood and scat samples collected from the same individuals, we statistically tested whether nine microsatellites previously designed for use in domestic cats can be used to identify individual black-footed cats. Genotypes recovered from blood and scat samples were compared to assess loss of heterozygosity, allele dropout, and false alleles resulting from DNA degradation or PCR inhibitors present in scat samples. The microsatellite markers were also used to identify individuals from scats collected in the field that were not linked to any blood samples. All nine microsatellites used in this study were amplified successfully and were polymorphic. Microsatellite loci were found to have sufficient discriminatory power to distinguish individuals and identify clones. In conclusion, these molecular markers can be used to monitor populations of wild black-footed cats noninvasively. The genetic data will be able to contribute important information that may be used to guide future conservation initiatives.

An experimental design for obtaining DNA of a target species and its diet from a single non-invasive genetic protocol

Next-generation sequencing technology has enabled accurate insights into the diet of wildlife species. The protocols for faecal sample collection and DNA extraction for diet analysis have differed from those focusing on target species, even in most studies combining questions on both aspects. We designed an experiment to evaluate two protocols using 11 parameters and select a single one that will generate both target species (Asiatic wild ass, Equus hemionus, in Israel) and diet DNA, as an effective strategy to minimise time, effort, and cost without hampering efficiency. In Protocol A, we swabbed the outer surface of faecal boluses and extracted DNA using a Stool Kit, while for Protocol B, we homogenised faecal matter from inside the bolus followed by extraction using a Powersoil Kit. Protocol A performed significantly better for four parameters, which included, for the target species, microsatellite amplification success and the quantity of the GAPDH gene; and for its diet, the number of exact sequence variants (ESVs) obtained at genus level and plant genus richness. However, there was no significant difference in the amplification success of sex-linked and plant markers, total reads at genus level, number of genera obtained and plant genus composition. Although we chose Protocol A, both protocols yielded results for the target species and its diet, demonstrating that one single protocol can be used for both purposes, although a pilot study is recommended to optimise the protocol for specific systems. This strategy may also be useful for studies combining target species and their gut microbiome and parasitic load.

Using genetic tools to inform conservation of fragmented populations of Asian elephants (Elephas maximus) across their range in China

A herd of 15 Chinese elephants attracted international attention during their 2021 northward trek, motivating the government to propose establishment of an Asian elephant national park. However, planning is hampered by a lack of genetic information on the remaining populations in China. We collected DNA from 497 dung samples from all 5 populations encompassing the entire range of elephants in China and used mitochondrial and microsatellite markers to investigate their genetic and demographic structure. We identified 237 unique genotypes (153 females, 84 males), representing 81% of the known population. However, the effective population size was small (28, range 25-32). Historic demographic contraction appeared to account for low haplotype diversity (Hd = 0.235), but moderate nucleotide and nuclear diversity (π = 0.6%, He = 0.55) was attributable to post-bottleneck recovery involving recent population expansion plus historical gene exchange with elephants in Myanmar, Lao PDR, and Vietnam. The 5 populations fell into 3 clusters, with Nangunhe elephants differing consistently from the other 4 populations (FST = 0.23); elephants from Mengyang, Simao, and Jiangcheng belonged to a single population (henceforth, MSJ), and differed from the Shangyong population (FST = 0.11). Interpopulation genetic variation reflected isolation by distance and female-biased dispersal. Chinese elephants should be managed as 2 distinct units: Nangunhe and another combining Shangyong and MSJ; their long-term viability will require restoring gene flow between Shangyong and MSJ, and between elephants in China and neighboring countries. Our results have the potential to inform conservation planning for an iconic megafaunal species.

Combining methods for non-invasive fecal DNA enables whole genome and metagenomic analyses in wildlife biology

Non-invasive biological samples benefit studies that investigate rare, elusive, endangered, or dangerous species. Integrating genomic techniques that use non-invasive biological sampling with advances in computational approaches can benefit and inform wildlife conservation and management. Here, we used non-invasive fecal DNA samples to generate low- to medium-coverage genomes (e.g., >90% of the complete nuclear genome at six X-fold coverage) and metagenomic sequences, combining widely available and accessible DNA collection cards with commonly used DNA extraction and library building approaches. DNA preservation cards are easy to transport and can be stored non-refrigerated, avoiding cumbersome or costly sample methods. The genomic library construction and shotgun sequencing approach did not require enrichment or targeted DNA amplification. The utility and potential of the data generated was demonstrated through genome scale and metagenomic analyses of zoo and free-ranging African savanna elephants (Loxodonta africana). Fecal samples collected from free-ranging individuals contained an average of 12.41% (5.54-21.65%) endogenous elephant DNA. Clustering of these elephants with others from the same geographic region was demonstrated by a principal component analysis of genetic variation using nuclear genome-wide SNPs. Metagenomic analyses identified taxa that included Loxodonta, green plants, fungi, arthropods, bacteria, viruses and archaea, showcasing the utility of this approach for addressing complementary questions based on host-associated DNA, e.g., pathogen and parasite identification. The molecular and bioinformatic analyses presented here contributes towards the expansion and application of genomic techniques to conservation science and practice.

Targeted genome-wide SNP genotyping in feral horses using non-invasive fecal swabs

The development of high-throughput sequencing has prompted a transition in wildlife genetics from using microsatellites toward sets of single nucleotide polymorphisms (SNPs). However, genotyping large numbers of targeted SNPs using non-invasive samples remains challenging due to relatively large DNA input requirements. Recently, target enrichment has emerged as a promising approach requiring little template DNA. We assessed the efficacy of Tecan Genomics’ Allegro Targeted Genotyping (ATG) for generating genome-wide SNP data in feral horses using DNA isolated from fecal swabs. Total and host-specific DNA were quantified for 989 samples collected as part of a long-term individual-based study of feral horses on Sable Island, Nova Scotia, Canada, using dsDNA fluorescence and a host-specific qPCR assay, respectively. Forty-eight samples representing 44 individuals containing at least 10 ng of host DNA (ATG’s recommended minimum input) were genotyped using a custom multiplex panel targeting 279 SNPs. Genotyping accuracy and consistency were assessed by contrasting ATG genotypes with those obtained from the same individuals with SNP microarrays, and from multiple samples from the same horse, respectively. 62% of swabs yielded the minimum recommended amount of host DNA for ATG. Ignoring samples that failed to amplify, ATG recovered an average of 88.8% targeted sites per sample, while genotype concordance between ATG and SNP microarrays was 98.5%. The repeatability of genotypes from the same individual approached unity with an average of 99.9%. This study demonstrates the suitability of ATG for genome-wide, non-invasive targeted SNP genotyping, and will facilitate further ecological and conservation genetics research in equids and related species.

Identifying individual ungulates from fecal DNA: a comparison of field collection methods to maximize efficiency, ease, and success

Non-invasive genetic sampling can facilitate the identification of individual animals across a landscape, with applications to management and conservation. Fecal material is a readily available source of DNA, and various methods exist for collecting fecal samples for DNA preservation. In particular, swab methods offer considerable promise, but their utility in real-world field contexts remains relatively untested. We systematically compared multiple genetic fecal sampling methods across all stages of data collection and analysis, including sampling in the field, DNA extraction in the lab, and identification of individuals using microsatellite genotyping. We collected 112 fecal samples from black-tailed deer (Odocoileus hemionus columbianus) in the field in Mendocino County, California, across a range of sample conditions of unknown age. We systematically compared the efficiency, ease, and genotyping success of three methods for field collection and storage of ungulate fecal samples: whole pellets in ethanol, whole dry pellets in paper envelopes, and cotton swabs in buffer. Storage method, sample condition, and their interaction predicted genotyping success in the top binomial GLMMs. We found that swabbing pellets resulted in the greatest percentage of individually identifiable genotypes (81%, compared to 60% for dry samples and 56% for ethanol), despite lower DNA concentrations. While swabbing pellets requires a greater time investment in the field, the samples are easier and safer to store and transport, and subsequent labwork is more efficient as compared to whole-pellet collection methods. We, therefore, recommend the swab method for most contexts. We provide additional recommendations and field protocols based on subsequent collection of 2284 swab samples for a larger monitoring study of the deer population, given that this large number of samples spanned a range of sample conditions and time spent in storage.

Non-invasive monitoring and reintroduction biology of the brush-tailed rock-wallaby (

Thirty-nine endangered brush-tailed rock-wallabies (Petrogale penicillata) were reintroduced to Grampians National Park, western Victoria, between 2008 and 2012. Subsequent high mortality, low breeding, and no recruitment were linked to fox predation and physical disturbance during monitoring. From 2014 to 2017, the colony was left undisturbed and monitored only by remote camera. Five adult animals were identified across this period (1 ♂ and 3 ♀s – all tagged; and one untagged female), and an average of 0.7 pouch young were birthed per tagged female per year. In 2019, camera-monitoring and non-invasive genetic monitoring (faecal) were used to identify colony members, genetic diversity, and breeding. Camera monitoring in 2019 identified the same five individuals, whereas genetic monitoring using 12 microsatellites identified eight individuals (two male and six female genotypes). Genetic diversity within the colony was moderate (expected heterozygosity (He) = 0.655, observed heterozygosity (Ho) = 0.854). Leaving the colony undisturbed after 2013 correlated with improved adult survival, increased breeding, and successful recruitment of young to the population. Recommendations for the Grampians colony include continuation of regular camera- and scat monitoring to improve our understanding of the reintroduction biology of P. penicillata and other marsupials in open, unfenced landscapes.

Novel microsatellites and investigation of faecal DNA as a non-invasive population monitoring tool for the banded hare-wallaby (

Monitoring programs for populations of small or medium-sized animals often use live-capture or photo-monitoring trapping methods to estimate population size. The banded hare-wallaby (Lagostrophus fasciatus), a small macropodiform marsupial, does not readily enter traps or have individually unique distinguishing physical features and is consequently difficult to monitor using these methods. Isolating DNA from faecal material to obtain individual genotypes is a promising monitoring technique and may present an alternative approach for this species. We developed novel species-specific microsatellite markers and undertook trials to assess faecal DNA degradation in ambient environmental conditions at two locations where this species has been translocated. The quality of DNA yielded from faecal pellets was evaluated through amplification failure and genotyping error rates of microsatellite markers. Error rates were compared for different treatments and exposure duration across multiple individuals. DNA was successfully obtained from all samples and error rates increased with exposure duration, peaking after 14–30 days depending on the site and treatment. The level of solar exposure was the most significant factor affecting degradation rate but both this and exposure duration had significant effects on amplification failure. Analysing DNA obtained from faecal pellets may represent a practical non-invasive method of deriving population estimates for this species and warrants further development.

Genotyping-in-thousands by sequencing (GT-seq) of non-invasive fecal and degraded samples: a new panel to enable ongoing monitoring of Canadian polar bear populations

Genetic monitoring using noninvasive samples provides a complement or alternative to traditional population monitoring methods. However, next‐generation sequencing approaches to monitoring typically require high quality DNA and the use of noninvasive samples (e.g., scat) is often challenged by poor DNA quality and contamination by nontarget species. One promising solution is a highly multiplexed sequencing approach called genotyping‐in‐thousands by sequencing (GT‐seq), which can enable cost‐efficient genomics‐based monitoring for populations based on noninvasively collected samples. Here, we develop and validate a GT‐seq panel of 324 single nucleotide polymorphisms (SNPs) optimized for genotyping of polar bears based on DNA from noninvasively collected faecal samples. We demonstrate (1) successful GT‐seq genotyping of DNA from a range of sample sources, including successful genotyping (>50% loci) of 62.9% of noninvasively collected faecal samples determined to contain polar bear DNA; and (2) that we can reliably differentiate individuals, ascertain sex, assess relatedness, and resolve population structure of Canadian polar bear subpopulations based on a GT‐seq panel of 324 SNPs. Our GT‐seq data reveal spatial‐genetic patterns similar to previous polar bear studies but at lesser cost per sample and through use of noninvasively collected samples, indicating the potential of this approach for population monitoring. This GT‐seq panel provides the foundation for a noninvasive toolkit for polar bear monitoring and can contribute to community‐based programmes – a framework which may serve as a model for wildlife conservation and management for species worldwide.

Estimating forest antelope population densities using distance sampling with camera traps

Traditional transect survey methods for forest antelopes often underestimate density for common species and do not provide sufficient data for rarer species. The use of camera trapping as a survey tool for medium and large terrestrial mammals has become increasingly common, especially in forest habitats. Here, we applied the distance sampling method to images generated from camera-trap surveys in Dja Faunal Reserve, Cameroon, and used an estimate of the proportion of time animals are active to correct for negative bias in the density estimates from the 24-hour camera-trap survey datasets. We also used multiple covariate distance sampling with body weight as a covariate to estimate detection probabilities and densities of rarer species. These methods provide an effective tool for monitoring the status of individual species or a community of forest antelope species, information urgently needed for conservation planning and action.

Revisiting traditional SSR based methodologies available for elephant genetic studies

Asian elephant (Elephas maximus) plays a significant role in natural ecosystems and it is considered as an endangered animal. Molecular genetics studies on elephants' dates back to 1990s. Microsatellite markers have been the preferred choice and have played a major role in ecological, evolutionary and conservation research on elephants over the past 20 years. However, technical constraints especially related to the specificity of traditionally developed microsatellite markers have brought to question their application, specifically when degraded samples are utilized for analysis. Therefore, we analyzed the specificity of 24 sets of microsatellite markers frequently used for elephant molecular work. Comparative wet lab analysis was done with blood and dung DNA in parallel with in silico work. Our data suggest cross-amplification of unspecific products when field-collected dung samples are utilized in assays. The necessity of Asian elephant specific set of microsatellites and or better molecular techniques are highlighted.

Current and Forthcoming Approaches for Benchmarking Genetic and Genomic Diversity

The current attrition of biodiversity extends beyond loss of species and unique populations to steady loss of a vast genomic diversity that remains largely undescribed. Yet the accelerating development of new techniques allows us to survey entire genomes ever faster and cheaper, to obtain robust samples from a diversity of sources including degraded DNA and residual DNA in the environment, and to address conservation efforts in new and innovative ways. Here we review recent studies that highlight the importance of carefully considering where to prioritize collection of genetic samples (e.g., organisms in rapidly changing landscapes or along edges of geographic ranges) and what samples to collect and archive (e.g., from individuals of little-known subspecies or populations, even of species not currently considered endangered). Those decisions will provide the sample infrastructure to detect the disappearance of certain genotypes or gene complexes, increases in inbreeding levels, and loss of genomic diversity as environmental conditions change. Obtaining samples from currently endangered, protected, and rare species can be particularly difficult, thus we also focus on studies that use new, non-invasive ways of obtaining genomic samples and analyzing them in these cases where other sampling options are highly constrained. Finally, biological collections archiving such samples face an inherent contradiction: their main goal is to preserve biological material in good shape so it can be used for scientific research for centuries to come, yet the technologies that can make use of such materials are advancing faster than collections can change their standardized practices. Thus, we also discuss current and potential new practices in biological collections that might bolster their usefulness for future biodiversity conservation research.

A simple sexing test for elephant species and its application to faecal DNA

We developed a novel real-time PCR assay for rapid sexing in all three elephant species, which amplifies small fragments of the orthologous sexual chromosome zinc finger protein genes ZFX/ZFY (65 bp). This assay is a simple, inexpensive and reliable tool that is suitable for non-invasive DNA samples and can be incorporated into larger SNP panels for individual identification and population genetic studies.

Anthropogenic pressures increase extinction risk of an isolated Asian elephant (Elephas maximus) population in southwestern China, as revealed by a combination of molecular- and landscape-scale approaches

Identification of the effect of anthropogenic threats on ecosystem is crucial. We used molecular tools and remote sensing to evaluate the population status of an isolated Asian elephant population in southwestern China in response to changes in habitat suitability between 1989 and 2019. A total of 22 unique genotypes were identified from 117 dung samples collected between March and June 2018 using microsatellite DNA analysis, including 13 males and 9 females. Based on the size of fecal boli, 1 animal was a juvenile, 9 were subadults, and 12 were adults, indicating that recruitment was limited. The effective population size was small (15.3) but there was no signature of a recent population bottleneck. We observed a low genetic diversity (H_e = 0.46 ± 0.05) and a high level of inbreeding (F_is of 0.43 ± 0.11), suggesting low population viability and high risk of extinction. In total, these elephants lost nearly two thirds (62%) of their habitat in 3 decades. The expansion of agriculture and rubber plantations followed by an increase in human settlements after 1989 increased the isolation of this population. We recommend that resettlement of 800 inhabitants of 2 villages and the abandonment of associated farmland and rubber plantations would make an additional 20 km² of suitable habitat available. This could allow a population increase of 14 elephants, possibly by translocating individuals from elsewhere in China. Our findings can be applied to the management and conservation of other fragmented populations in China or in other range countries of Asian elephants.

Factors influencing genotyping success and genotyping error rate of Eurasian otter (Lutra lutra) faeces collected in temperate Central Europe

The use of non-invasively collected DNA source material for genetic and genomic applications is usually characterized by low target DNA concentration and quality, genotyping errors and cost-intensive lab procedures. However, for otters (Lutrinae) as elusive species of conservation concern, genetic non-invasive sampling has become an important tool to study their ecology and demography. To increase cost-efficiency of monitoring programmes and to promote the expansion of genomic approaches to non-invasive samples, we aimed to refine sample collection and preparation. Therefore, we examined the effects of intrinsic sample characteristics (including diet), environmental conditions in the field and sample treatment in the molecular laboratory on the success of genotyping and allelic dropout (ADO) rates using microsatellite markers in 1970 fresh Eurasian otter (Lutra lutra) scats. Using fresh samples only, we probably eliminated one of the most important impediments of genotyping DNA from otter faecal samples beforehand. But, we observed higher genotyping success and lower ADO rates for anal glad secretions and faecal samples containing high proportions of mucus. Moist conditions during sample collection may promote DNA degradation and PCR inhibition, leading to decreased genotyping success rates. ADO was further affected by the type of extraction kit. However, a high proportion of variance remaining unexplained by our models implied that additional parameters were acting (amount of PCR inhibitors, non-uniform distribution of intestinal cells, efficiency of PCRs, specific microclimate at marking sites). We summarized influential factors maximizing genotyping quality of otter scats and give recommendations for sample collection, storage and DNA extraction based on our results and current literature.

QUANTITATIVE and QUALITATIVE TEST of THE FECAL SAMPEL FROM SUMATRAN ELEPHANT (Elephas maximus sumatranus)

Sumatran Elephants (Elephas maximus sumatranus) is one of the endemic Sumatran fauna that is protected by Indonesia Law. The Remnant Forest of Acacia District Penyabungan in the landscape of Padang Sugihan is one of the elephant’s habitats in South Sumatra. Habitat degradation and fragmentation, poaching and conflicts become the major threats for the elephant population. Genetic study is one of the efforts to establish a conservation policy. It is necessary to test the quantitative and qualitative of DNA, at the extractions stage from fecal samples, in order to get the standard results on DNA concentration which will be analyzed later. The method used is through direct observation as the initial survey to determine the sampling location. Fecal samples were preserved in absolute ethanol at -20°C.  The extraction process was carried out using the Quick-DNATM Fecal/Soil Microbe Miniprep Kit. Samples were tested quantitatively using a Nanodrop Thermo Scientific, with the expectation that the concentration results were considered to be 1.6-1.8 and continued with the qualitative test of DNA through electrophoresis gel agarose and UV Transilluminator. Of the 20 samples, only 12 samples showed positive results (there were DNA bands). The results of this quantitative and qualitative test could be used to determine a viable sample to be used as a product in the genetic analysis stage of Sumatran Elephants in the Remnant Forest of Acacia South Sumatra.