Assessing pangolin scale morphology and genetic identifiability following varied processing treatments

Authors:
  • KHKum Chew Hiong
    Kum Chew Hiong
  • JOJasmine Ong
    Jasmine Ong
  • AWAlvin Wee
    Alvin Wee
  • ACAmy Hee Joo Chan
    Amy Hee Joo Chan
  • SLShizhe Li
    Shizhe Li
  • XPXiaoge Ping
    Xiaoge Ping
  • YZYan Zeng
    Yan Zeng
  • RXRenhui Xie
    Renhui Xie
  • CHChoon Beng How
    Choon Beng How
  • CFCharlene Judith Fernandez
    Charlene Judith Fernandez
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Abstract
Pangolins are among the most heavily trafficked mammals worldwide, with their scales widely traded for traditional medicine. Recent enforcement reports highlight an emerging challenge which involves the trafficking of processed scales, which are more difficult to visually recognise and often with degraded DNA. As processing alters both morphology and DNA integrity, reliable species identification from such material is uncertain, yet remains essential for forensic investigation and enforcement as well as conservation. Here, we experimentally assessed the impacts of four trade-reported processing treatments on Sunda pangolin ( Manis javanica ) scales. We quantified changes in physical traits (length, width, thickness, and hardness) and evaluated how processing affected DNA quantity and consequently, molecular identification success using Bayesian logistic regressions. We found that processing altered scale appearance (causing thickening, yellowing, blistering, and burnt marks) but diagnostic morphological features remained intact, enabling recognition of pangolin origin. To support enforcement practice, we provided a guide for morphological identification of processed scales. DNA quantity was also not a strong predictor of species assignment; while higher concentrations improved identification success, many low-yield samples still produced viable sequences. Despite processing treatments causing DNA degradation, we found that the overall probability of successful species identification across treatments remained at 89.7%, with even the most damaging treatment of frying with sand plus vinegar quenching, still yielding a relatively high probability of identification of 76.3%. These findings emphasise the importance of an integrative approach to processed scale identification, with morphological traits providing a rapid and accessible first line of assessment, while molecular tools providing confirmation and resolution.

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