About

Samuel K Wasser is a Research Professor in the Department of Biology at the University of Washington and the Director of the Center for Conservation Biology. His laboratory pioneered the development and application of tools to measure DNA, hormones, and toxicants in wildlife scat, which is the most accessible animal product in nature. These tools allow wildlife managers to gain a physiological window into how multiple environmental pressures impact wildlife, by determining species, sex, individual identities, diets, stress levels, reproductive health, and toxicant exposure from noninvasive samples. His work has been adopted by hundreds of investigators worldwide. Dr. Wasser's research has significant forensic applications, including identifying poaching hotspots in Africa through DNA analysis of ivory tusks and linking shipments to major transnational criminal organizations using genetic matching and AI-based handwriting signature analysis. His efforts have expanded to capacity building programs across Africa to empower local conservation and management efforts. He holds a B.Sc. in Zoology from Michigan State University, an M.Sc. in Zoology from the University of Wisconsin-Milwaukee, and a Ph.D. in Animal Behavior from the University of Washington. He was the first recipient of the H.F. Guggenheim Career Development Award and the Research Scientist Development Award from the Smithsonian Institution. Wasser was awarded the endowed chair in Conservation Biology by the University of Washington and has received numerous honors, including the Environmental Leadership Award, Elephant Hero Award, and the Wildlife Crime Tech Challenge Grand Prize. His research focuses on conservation biology, ecology, physiology, and forensic methods to combat wildlife crime and understand environmental impacts on wildlife populations.

Research topics

• Sociology
• Ecology
• Biology
• Socioeconomics
• Fishery
• Zoology
• Psychology
• Social psychology
• Geography
• Demography

Selected publications

• Distribution of African savanna elephants (Loxodonta africana), African forest elephants (L. cyclotis), and their hybrids across Africa based on genetic evidence

  Global Ecology and Conservation · 2025-03-11 · 4 citations

  articleOpen accessSenior author

  It has recently been recognized that African forest and savanna elephants represent separate species. We analyzed 2445 known-origin elephant samples from across Africa for presence of the two species and hybrids between them, and augmented this with hybrid detection in 4883 samples from ivory seized as contraband. Hybrids were rare overall (6.6% of reference samples, 1.5% of contraband samples), occurring only in areas in or near forest-savanna ecotones. Of our known-location hybrids, 117/167 (70%) were in the Albertine Rift major hybrid zone in eastern DRC and southwestern Uganda, confirming previous reports; in some Albertine sites hybrids outnumbered pure species. Hybrids inferred to be F1 (the product of a forest/savanna mating) were particularly rare, with only 4 found in reference samples and 5 in contraband, suggesting that most hybridization occurred two or more generations ago. We discuss the distribution of the two African elephant species and their hybrids, forces driving hybridization, implications for conservation and management, and areas that need additional sampling effort.

  PublisherDOI

• AI-Driven Detection and Analysis of Handwriting on Seized Ivory: A Tool to Uncover Criminal Networks in the Illicit Wildlife Trade

  ArXiv.org · 2025-08-13

  preprintOpen accessSenior author

  The transnational ivory trade continues to drive the decline of elephant populations across Africa, and trafficking networks remain difficult to disrupt. Tusks seized by law enforcement officials carry forensic information on the traffickers responsible for their export, including DNA evidence and handwritten markings made by traffickers. For 20 years, analyses of tusk DNA have identified where elephants were poached and established connections among shipments of ivory. While the links established using genetic evidence are extremely conclusive, genetic data is expensive and sometimes impossible to obtain. But though handwritten markings are easy to photograph, they are rarely documented or analyzed. Here, we present an AI-driven pipeline for extracting and analyzing handwritten markings on seized elephant tusks, offering a novel, scalable, and low-cost source of forensic evidence. Having collected 6,085 photographs from eight large seizures of ivory over a 6-year period (2014-2019), we used an object detection model to extract over 17,000 individual markings, which were then labeled and described using state-of-the-art AI tools. We identified 184 recurring "signature markings" that connect the tusks on which they appear. 20 signature markings were observed in multiple seizures, establishing forensic links between these seizures through traffickers involved in both shipments. This work complements other investigative techniques by filling in gaps where other data sources are unavailable. The study demonstrates the transformative potential of AI in wildlife forensics and highlights practical steps for integrating handwriting analysis into efforts to disrupt organized wildlife crime.

  PublisherOA PDFDOI

• Pangolin hunting in southeast Nigeria is motivated more by local meat consumption than international demand for scales

  Nature Ecology & Evolution · 2025-06-13 · 7 citations

  articleOpen access

  Thousands of species are threatened by overexploitation, often driven by a complex interplay of local and global demand for various products-a dynamic frequently overlooked in wildlife trade policies. African pangolins, regarded as the world's most trafficked wild mammals, are a heavily exploited group for different reasons across geographic scales. However, it remains unclear how far the burgeoning trafficking of their scales to Asia for medicine drives their exploitation compared with local meat demand. Here, using data collected from questionnaires distributed to 809 hunters and meat vendors in Nigeria, the world's biggest hub for pangolin trafficking, we show that targeted pangolin hunts are uncommon in the country's largest pangolin stronghold. Instead, 97% of pangolins are captured opportunistically or during general hunting, with 98% of these caught for meat and mostly either eaten by hunters (71%) or traded locally (27%), potentially due to the meat's exceptionally high palatability. Meanwhile, around 70% of scales are discarded, with less than 30% sold. In addition, local meat prices are three to four times higher than those for scales. Our findings highlight the need to consider entire wildlife trade chains in international policies.

  PublisherOA PDFDOI

• Elephant range and population, strontium isotopes, and genetics combine to give local-scale specificity to ivory hotspot tracking

  Isotopes in Environmental and Health Studies · 2025-12-08

  article

  Sr ratios of the seized ivory samples and elephant population estimates from individual Elephant Polygons we find that at least 75 % of the samples likely came from a single Elephant Polygon which includes the Tsavo National Parks in Kenya and the Mkomazi National Park in Tanzania. A few samples may have come from other regions, most likely from Tanzania. This study illustrates the value of combining genetics, isotope geochemistry, and population surveys in wildlife forensics studies.

  PublisherDOI

• Elephants inhabiting two forested sites in western Uganda exhibit contrasting patterns of species identity, density, and history of hybridization

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-05-17 · 2 citations

  preprintOpen access

  Abstract Elephant populations across much of Africa face severe rates of decline due to poaching and habitat loss. The recent decision by the International Union for the Conservation of Nature (IUCN) to separately list African forest ( Loxodonta cyclotis ) and savanna ( L. africana ) elephants on the IUCN Red List both highlights the different threats of extinction faced by these two species and emphasizes the need for genetic data to classify taxonomically undefined populations across the continent. This includes western Uganda – a region that harbors the largest known modern hybrid zone between the two species. We combined a new high-throughput amplicon sequencing (HTAS) approach with fecal DNA-based Capture Mark Recapture (CMR) analysis to infer the population sizes and species compositions of elephants living in two forests. We demonstrate that Kibale National Park hosts a relatively large elephant population (573 individuals, 95% CI: 410 to 916; 0.72 elephants/km 2 ) composed primarily of hybrids (81.5%) and savanna elephants (17.7%), while Bwindi Impenetrable National Park hosts a smaller population (96 individuals, 95% CI: 64 to 145; 0.29 elephants/km 2 ) composed of forest elephants (86.8%) and hybrids (13.2%). We then sequenced maternally inherited (mtDNA) and paternally inherited (AMELY) genetic markers and found that the two parks’ populations exhibit different patterns of sex-linked genetic variation. The contrasting patterns of species identity and genetic variation between these parks demonstrate different histories of hybridization and highlight the importance of site-specific monitoring where elephants are taxonomically undefined.

  PublisherOA PDFDOI

• javascript:void(0) Scat DNA reveals distinct lineage of Chinese pangolin in Nepal: Implications for Conservation and Wildlife Forensics.

  2024-09-04

  preprintOpen access

  Pangolins are under severe threat from illegal trade and habitat loss. Despite their conservation significance, these elusive creatures remain poorly understood, particularly in the context of phylogeography and genetic diversity. In this study DNA was isolated from two types of pangolin scat (faeces) samples (whole scat and swabs) which had been stored frozen for up to 3 years between the time of collection and our analyses. A mitochondrial sequence for the cytochrome b gene (424 bp) region was reliably generated from both sample types, for scats which appeared in ‘good’ or ‘poor’ condition at the time of collection. Sanger sequencing revealed four new cytochrome b haplotypes for pangolin, with variations in distinct sampling regions in Nepal (central and east). Comparison to reference sequences for pangolin originating from China, Taiwan and Thailand, indicated a distinct variant of Chinese pangolin in Nepal (15-19 base pair difference). Genetic differentiation of Chinese pangolin in Nepal has broader conservation significance for this species. Methods described here are robust and could be applied to broader genetic studies of pangolin populations across Nepal, allowing for genetic mapping of pangolin variations to assist in identifying populations of significance, evaluation of conservation interventions, and forensic applications supporting the fight against illegal poaching.

  PublisherOA PDFDOI

• Genetic confirmation of a hybridization zone of forest and savannah elephants at the extreme north of Kibale forest, Uganda

  2024-01-30

  preprintOpen access

  After a long-standing debate, African elephants, listed as Vulnerable on the IUCN Red list of Threatened Species, are now considered by the IUCN as two distinct species: savannah elephants ( Loxodonta africana ) and forest elephants ( Loxodonta cyclotis ), the latter being severely threatened by forest loss, fragmentation and degradation due to agriculture expansion, as well as by the illegal ivory trade. Although the two species have different habitat preferences, their range overlaps in some ecotones; despite an ancient separation between these two species, hybrids have been reported in four locations. The main area of hybridization known today is located on the DRC-Uganda border, but remains understudied. Using 15 microsatellites, we aimed to investigate this hybridization zone by determining the species and hybrid status of 177 fecal samples collected in the area of Sebitoli, at the extreme North of Kibale National Park. Surprisingly for a forest area, no pure forest elephants were detected. Out of the 91 individuals sampled a very large proportion (81.3%) were hybrid individuals mainly from a second generation or more. Only 18.7% of pure savannah elephants were detected, all originating from the DRC-Uganda border. Further analyses are necessary to assess the age of this hybridization zone. Our results emphasize that hybrids and savannah elephants can successfully range in forested area. They also show that forest elephants are rare even in their native habitat. The proposed amendment of IUCN regarding the African elephant taxonomy may help to better conserve the threatened forest elephant.

  PublisherOA PDFDOI

• Shifts in fisher (Pekania pennanti) diet in response to climate-induced tree mortality in California assessed with DNA metabarcoding

  Journal for Nature Conservation · 2023-04-13 · 9 citations

  articleOpen access

  A recent climate-induced tree mortality event in California, USA has led to dramatic landscape-level changes in the southern Sierra Nevada. Wide-spread conifer mortality was documented in habitat occupied by fisher (Pekania pennanti), a mature-forest associated species of conservation concern in this region. We analyzed fisher scats collected on the Sierra National Forest from the pre-tree-mortality period (PreTM, 2011 – 2013) and post-tree-mortality period (PostTM, 2017 – 2018). We used DNA metabarcoding to successfully identify taxa and summarized diet composition for 109 PreTM and 102 PostTM fisher scats. We observed 48 different diet items (33 assigned to species and 15 to genus). Mammals, birds, and plants of the Ribes genus (gooseberries and currents) comprised the highest proportions of diet items, although scats also contained DNA from reptiles, insects, arachnids, snails, and fungi. The frequency of occurrence of mammalian prey items was lower in PostTM (49.0%) versus PreTM scats (81.7%) with a reduction in the occurrence of two tree squirrels (Douglas squirrel and Humboldt’s flying squirrel). A higher proportion of scats collected PostTM (46.1%) contained DNA from Ribes spp. versus scats collected PreTM (19.3%). Our data reveal potential cascading effects of climate-induced tree mortality on fisher diet in the southern Sierra Nevada. Flexibility in fisher diet, however, may allow resilience to ecological change though future studies should consider the behavioral, energetic, demographic or fitness consequences from a shift away from medium-sized mammalian prey to plants.

  PublisherDOI

• Large-scale population genomics of Malayan pangolins reveals deep diversification and a new species

  bioRxiv (Cold Spring Harbor Laboratory) · 2023-08-07 · 1 citations

  preprintOpen access

  Abstract Background Archipelagos and oceanic islands often present high percentage of endemism due to rapid speciation. The Malayan pangolin is a species distributing at both mainland (southern Yunnan, China) and oceanic islands via Malayan peninsula, which may result in deep differentiation among populations. In-depth investigation of population structure and genetic consequences for such species is of vital importance for their protection and conservation, practically for the critically endangered Malayan pangolin that is suffering from poaching, illegal trade, and habitat loss. Results Here we carried out a large-scale population genomic analysis for Malayan pangolins, and revealed three highly distinct genetic populations in this species, two of which are now being reported for the first time. Based on multiple lines of genomic and morphological evidence, we postulate the existence of a new pangolin species ( Manis _1). Genetic diversity and recent inbreeding were both at a moderate level for both Malayan pangolins and Manis _1, but mainland Malayan pangolins presented relatively lower genetic diversity, higher inbreeding and fitness cost than island populations. Conclusions We found extremely deep and graded differentiation in Malayan pangolins, with two newly discovered genetic populations and a new pangolin species that is closely related to the Philippine pangolin than the typical Malayan pangolin, but a distant relative of the Indian pangolin. Anthropogenic factors did not significantly weaken the basis of genetic sustainability for Malayan pangolins, but mainland Malayan pangolins should be paid more attention for conservation due to higher genetic risks than island populations.

  PublisherOA PDFDOI

• Uncovering the magnitude of African pangolin poaching with extensive nanopore DNA genotyping of seized scales

  Conservation Biology · 2023-08-08 · 14 citations

  articleOpen access

  Trade in pangolins is illegal, and yet tons of their scales and products are seized at various ports. These large seizures are challenging to process and comprehensively genotype for upstream provenance tracing and species identification for prosecution. We implemented a scalable DNA barcoding pipeline in which rapid DNA extraction and MinION sequencing were used to genotype a substantial proportion of pangolin scales subsampled from 2 record shipments seized in Singapore in 2019 (37.5 t). We used reference sequences to match the scales to phylogeographical regions of origin. In total, we identified 2346 cytochrome b (cytb) barcodes of white-bellied (Phataginus tricuspis) (from 1091 scales), black-bellied (Phataginus tetradactyla) (227 scales), and giant (Smutsia gigantea) (1028 scales) pangolins. Haplotype diversity was higher for P. tricuspis scales (121 haplotypes, 66 novel) than that for P. tetradactyla (22 haplotypes, 15 novel) and S. gigantea (25 haplotypes, 21 novel) scales. Of the novel haplotypes, 74.2% were likely from western and west-central Africa, suggesting potential resurgence of poaching and newly exploited populations in these regions. Our results illustrate the utility of extensively subsampling large seizures and outline an efficient molecular approach for rapid genetic screening that should be accessible to most forensic laboratories and enforcement agencies.

  PublisherOA PDFDOI

Recent grants

• NIH Grant R01MH045863

  NIH · $118k · 1993

Frequent coauthors

• Jennifer A. Hempelmann

  NOAA National Marine Fisheries Service Northwest Fisheries Science Center

  67 shared

• Kim M. Parsons

  NOAA National Marine Fisheries Service

  65 shared

• Candice K. Emmons

  National Oceanic and Atmospheric Administration

  60 shared

• M. Bradley Hanson

  National Oceanic and Atmospheric Administration

  60 shared

• Michael J. Ford

  NOAA National Marine Fisheries Service

  54 shared

• Katherine L. Ayres

  53 shared

• Kenneth C. Balcomb

  Center for Whale Research

  52 shared

• Gregory S. Schorr

  Marine Ecology and Telemetry Research

  51 shared

Labs

• Wasser LaboratoryPI

Education

• B.S., Zoology

  Michigan State University

• M.S., Zoology

  University of Wisconsin-Milwaukee

• Ph.D., Animal Behavior

  University of Washington

Awards & honors

• H.F. Guggenheim Career Development Award (1984)
• Research Scientist Development Award, Smithsonian Institutio…
• Endowed Chair in Conservation Biology, University of Washing…
• Environmental Leadership Award, Alberta Emerald Foundation (…
• Elephant Hero Award, National Geographic Society (2015)