International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.3, 101-110 http://ecoevopublisher.com/index.php/ijmec 104 3.3 Direct hunting and illegal trade In the complex relationship between humans and snakes, direct hunting and illegal trade are one of the most obvious factors affecting snake diversity. This human-induced death and predatory collection directly reduce the number of snakes in the wild and damage the population structure (Reading et al., 2010). Direct hunting of snakes by humans is common in many parts of the world due to fear, disgust, or other prejudices or profit-driven reasons (Figure 1) (Pandey et al., 2016; Landová et al., 2020). The threat of illegal trade to snake diversity is becoming increasingly prominent. The trade of snakes and their products, including live pets, snake skins and leather, Chinese medicinal materials, and table game, has formed a transnational profit chain. Studies have shown that more than 35% of reptile species in the world have trade records on the Internet, of which about three-quarters are not on the CITES control list (Marshall et al., 2020). Faced with this situation, countries and international organizations have taken measures to curb illegal snake trade. Figure 1 Types of snakes that humans generally fear and hate (Adopted from Landová et al., 2020) Image caption: A): fear-eliciting snakes: Sahara sand viper (Cerastes vipera), Sochurek's saw-scaled viper (Echis carinatus sochureki) and Gaboon viper (Bitis gabonica); B) disgust-eliciting snakes: Eurasian blind snake (Xerotyphlops vermicularis), northern rubber boa (Charina bottae), and brahminy blindsnake (Indotyphlops braminus) (Adopted from Landová et al., 2020) 3.4 Alien species invasion and ecological substitution The impact of alien invasive species on snake diversity is a complex and vigilant issue. Invasive species can directly or indirectly harm local snake populations through predation competition, habitat change, disease transmission and other means (Reading et al., 2010). A typical case is the killing of snakes by invasive predators. For example, after the introduction of the Indian mongoose to Reunion Island in the Indian Ocean, the native blunt-headed snakes on the island were preyed on in large numbers, and the population once dropped by more than 90% (Van Moorleghem et al., 2019; Subrata et al., 2020). Another typical case is the poisoning of snakes by invasive amphibians. The cane toad (Rhinella marina) introduced to Australia in the 20th century secretes highly toxic substances. Many local snakes (such as the death pit viper and the king snake) will soon be poisoned and die after accidentally eating the toad (Phillips and Shine, 2006). The competition of alien invasive species on snakes cannot be ignored. Some invasive predators may occupy similar ecological niches as native snakes, causing competition for food and space, thus replacing the ecological role of snakes. In addition, invasive species may carry new pathogens, posing a health threat to native snakes. 3.5 Superimposed impacts of climate change Global climate change is considered one of the main factors threatening biodiversity in the coming decades, and its impact on snake diversity often occurs in combination with other disturbances (Reading et al., 2010). Rising temperatures and changes in precipitation patterns will directly affect the physiological ecology of snakes. For example, warming may expand the potential distribution range of some drought-tolerant snake species while reducing the suitable habitat for snake species that rely on moist forests (Martinez et al., 2024). Frequent extreme weather events are also a major feature of climate change, which has a severe impact on snake habitats and populations. Continuous droughts may lead to a sharp decline in snake prey such as amphibians, which in turn causes snake species that feed on frogs to starve (Zipkin et al., 2020).
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