Reptiles are remarkable creatures with adaptations such as the Coachella Valley fringe-toed lizard’s scaly hind toes that help it sink into sand while running, or the hellbender’s loose frilly skin that helps it breathe. They also provide key ecosystem services and enrich our enjoyment of nature.
파충류분양Comprehensive extinction-risk assessments have long been available for birds, mammals and amphibians, allowing them to inform conservation policy and practice. However, a global reptile assessment has until recently been lacking.
Threats
As with amphibians and mammals, habitat loss is a major threat to reptiles. This happens when land is cleared for agriculture, logging or urban development. It can also happen when human activities contaminate natural water sources, which is especially troublesome for reptiles that live in or near rivers and other aquatic habitats. This includes accidental spills of herbicides, pesticides, sewage and other chemicals, as well as the intentional release of fuels, solvents and cleaning agents for construction or maintenance work.
Chemicals can also contaminate the air, affecting reptiles that breathe through their skin. This can lead to a variety of health problems, including respiratory distress and infertility.
A new study finds that more than 40 percent of reptile species face extinction, which is more than the rates for amphibians and birds. The researchers found that conservation efforts for other forest-dwelling creatures have benefited reptiles to some extent, but they need more targeted and urgent efforts, particularly for island endemic lizards and crocodiles facing the dangers of invasive predators or the pet trade. They also need to address the looming threat of climate change, which may affect some reptiles by altering thermally viable windows for foraging or skewing offspring sex ratios in species with temperature-dependent sex determination.
Habitat Loss
Reptile conservation efforts focus on addressing habitat loss through the protection or restoration of natural habitats for turtles and tortoises, snakes and lizards, crocodiles and alligators, and frogs and toads. These groups typically work to educate people on the need to conserve these species and seek solutions to protect their natural habitats from human disturbance.
Globally, anthropogenic factors that increase reptile extinction risk most frequently include agriculture and urban development (Fig. 3a). In general, threats that cause habitat change affect proportionately more reptiles than those that lead to habitat destruction. These threats include logging, fire, and road construction.
Illegal hunting also poses a significant threat for many reptile species. This is particularly true of species with low population density and small geographic ranges. Moreover, long-lived species with slow life history traits are predisposed to increased extinction risk due to over harvesting. These threats are exacerbated by the lack of effective legislation to control the wildlife trade. This is a global problem that requires attention and investment to reduce.
Illegal Hunting
Many reptile species are targeted for their skins, meat or as pets. This ongoing trade can have a profound impact on the number of reptiles in the wild. Even purchasing reptile products that are legally harvested and exported can encourage further hunting.
Currently, nearly all reptiles traded internationally are caught illegally. Using data from LEMIS, we found that 36% of the traded reptiles are wild-caught individuals, four times more than those monitored via CITES. A major gap between the regulation of the pet trade and source population health leaves vulnerable endemic species susceptible to over-exploitation. Furthermore, gaps in conservation assessments allow for the exploitation of new species described within years of their discovery, resulting in unknown impacts on numerous endangered reptiles.
A focus on law enforcement in wildlife trade hotspots can mitigate this problem, as will improving the quality of captive breeding documentation. But this will only be effective if legal trade can decrease demand for the capture of native species. Without significant improvements to captive breeding and export requirements, the illegal trade in reptiles will persist.
Diseases
Reptiles are particularly vulnerable to diseases, and many species have experienced dramatic declines because of them. Widespread disease outbreaks affecting herpetofaunal (reptiles and amphibians) populations have been the result of introduced pathogens, including chytrid fungi and ranaviruses. Many of these pathogens have environmental reservoirs, and may persist outside herpetofaunal hosts for days to months. This enables indirect transmission pathways and sustained transmission events even as populations decline.
Climate change also affects herpetofaunal health by changing the amount of time each day that temperatures are right for foraging and by skewing sex ratios in species with temperature-dependent sex determination. Additionally, keratin-based barriers in reptile skins are compromised by skin lesions and molting retention. These conditions facilitate epidermal colonization by fungal pathogens such as Nannizziopsis spp. and Ophidiomyces ophiodiicola, which cause Snake Fungal Disease in wild populations of many saurian species.
In addition to the threats outlined above, reptiles are impacted by infectious diseases transmitted through arthropod vectors. Vector-borne diseases of zoonotic concern include bacteria, protozoa and viruses. Jenna Palmisano earned her BS from Stetson University where she majored in aquatic and marine biology and minored in environmental studies. She is currently a PhD student in Dr. Anna Savage’s lab at the University of Central Florida where she is studying the molecular and organismal consequences of an invasive lung parasite, Raillietiella orientalis, on pygmy rattlesnake (Sistrurus miliarius) at genetic, individual, and population scales.
Disease Transmission
Reptiles are natural hosts for a number of bacteria, protozoa and viruses that are of zoonotic concern. The phyletic origin of reptiles has favored co-evolution with hematophage arthropod vectors including the subclass Acarina (mite species such as fleas, ticks and sand flies) and the order Diptera (mosquitoes, sand flies, tsetse flies and hymenopterans).
As a consequence of their varied habitat requirements and long lifespans, many reptiles serve as reservoirs for hematophage pathogens, especially the Salmonella group. Some hematophage species that parasitize reptiles also parasitize humans and livestock (e.g., the mite genus Ophionyssus natricis that causes hemorrhagic disease in snakes).
Habitat management efforts should provide for connectivity among important reptile habitats such as riparian corridors along safe upland dispersal routes, basking habitats, overwintering hibernacula and aquatic breeding sites. In addition, reptiles kept as pets may represent a risk to humans for infection via direct contact or fecal contamination. Zoonoses from reptiles are a significant source of illness and death in people, especially children, the elderly and individuals with immune deficiency or pregnancy.