DOI: 10.5061/dryad.r4xgxd2gc
title: Home and hub: pet trade and traditional medicine impact reptile populations in source locations and destinations

description: The pet trade and Traditional Chinese Medicine (TCM) consumption are major
 drivers of global biodiversity loss. Tokay geckos (Gekko gecko) are among
 the most traded reptile species worldwide. In Hong Kong, pet and TCM
 markets sell tokay geckos while wild populations also persist. To clarify
 connections between trade sources and destinations, we compared genetics
 and stable isotopes of wild tokays in local and nonlocal populations to
 dried individuals from TCM markets across Hong Kong. We found that TCM
 tokays are likely not of local origin. Most wild tokays were related to
 individuals in South China, indicating a probable natural origin. However,
 two populations contained individuals more similar to distant populations,
 indicating pet trade origins. Our results highlight the complexity of
 wildlife trade impacts within trade hubs. Such trade dynamics complicate
 local legal regulation when endangered species are protected, but the same
 species might also be non-native and possibly damaging to the environment.
description: Sampling Design Both <em>G. gecko
 gecko</em> and <em>G. gecko reevesii</em> seem to occur
 in different areas of Hong Kong, with two main populations described on
 Lantau Island and Lion Rock Country Park, and smaller populations possibly
 established through intentional or unintentional release from the pet
 trade [23]. We surveyed seven field sites across Hong Kong for which the
 presence of tokay geckos was known, between August and November 2020.
 Precise locations are kept confidential to limit risks of poaching [27].
 We caught geckos by hand or butterfly net. Upon capture, we collected
 morphological information on snout-vent length (SVL), total length (TL),
 sex, morph (red- vs. black-spotted), and mass. We took pictures of ventral
 and dorsal sides with a uniform background for further reference. We
 collected a small tail clipping (~0.5cm) from each animal, half stored in
 70% ethanol (for genetic study) and half in an empty tube (for stable
 isotope analysis). As the tail is capable of regeneration this was deemed
 the least invasive method for this study [28]. For dried specimens, we
 purchased 19 pairs of dried tokay geckos (Figure S1) allegedly originating
 from China, Thailand, and Vietnam from 18 shops in Hong Kong (Table S1).
 All shops were given an identification letter to preserve anonymity. We
 also obtained shed skins from two pet tokays that had been in captivity
 more than 1.5 years, from volunteer pet owners. The two pet owners
 mentioned that the tokay geckos they purchased from local pet shops were
 allegedly sold as “wild”. Additionally, we received the corpse of one wild
 individual, found dead in Lantau Island.  Stable
 Isotope Analysis We used stable isotope analyses (SIA)
 to infer breeding conditions and/or geographic origin of TCM geckos. We
 compared δ<sup>15</sup>N and δ<sup>13</sup>C from
 tail samples from wild-caught and TCM geckos. We selected tail tissue as
 it has a lower turnover in isotopic ratios compared to other tissues in
 lizards and therefore represents better the long-term diet. SIA has
 previously been used on a wide range of animals, including reptiles, to
 differentiate diet between different breeding conditions (captive,
 semi-captive, or wild) based on differences in the ratios of heavy to
 light isotopes of C and N in their diet (δ<sup>13</sup>C and
 δ<sup>15</sup>N). Here, we studied the potential overlap
 between the diet of TCM shops and HK wild-caught tokay geckos.
 For SIA, 0.5cm of the tip of the tail of the wild and TCM shop
 individuals was dried at 60°C in a chamber for 24 hours minimum and
 subsequently cut into small aliquots of ~1mg (1.35±0.12 mg) and loaded
 into tin capsules. Analysis was conducted using an EA-IRMS (Eurovector
 3028-Nu Instruments Perspective IRMS) at the Stable Isotope Ratio Mass
 Spectrometry (SIRMS) Laboratory at HKU, using a certified standard
 (Indiana University acetanilide, (δ<sup>13</sup>C = −29.53 ‰,
 δ<sup>15</sup>N = +1.18 ‰) to correct the resulting sample
 values. Results were reported as a ratio to the reference values from Hong
 Kong and expressed in δ units in the conventional permil notation, where δ
 =
 [(R<sub>sample</sub>/R<sub>standard</sub>)−1]×1000.  Shop Surveys We visited 18 registered TCM shops on three different days between February and April 2021 in three main districts of Hong Kong (Sham Shui Po, Sheung Wan, and Yau Ma Tei) and carried out nine interviews in Cantonese. Questionnaires were composed of a series of open- and closed-ended questions (Table S2; adapted from Landry Yuan et al.), around several main themes: background on the shop, consumption of geckos, origin of the products and import, and trends. Interviews were conducted by the same interviewers in Cantonese following a semi-structural oral format. Answers from interviewees were written down and later translated into English for further analysis. Each interviewee gave consent and was offered the option to skip any question he or she was not comfortable answering. Surveys were later anonymized.
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