EarthTalk: How are reptiles doing today in the face of climate change and other environmental threats? | Columnists


Dear EarthTalk: How are reptiles doing today in the face of climate change and other environmental threats?

— LM Smith, Boston, MA

Reptiles, like other animals and plants, face increasing threats as human influence on the environment increases. Some reptiles are particularly threatened; about 61% of turtles are threatened or extinct. However, it has been difficult to track the exact consequences of human activity on reptiles, as research has mainly focused on mammals and birds – which attract more public attention – although assessments have revealed that reptiles were more endangered than birds.

A recent study that observed 10,196 species determined that 21.1% of reptiles are threatened with extinction. These species contain approximately 15.6 billion years of phylogenetic diversity (PD). This science uses a phylogenetic tree, which shows how closely related species are, to describe the amount of biodiversity in an ecosystem and get a more useful measure than just counting the number of species. In addition, reptile adaptations to ecological conditions help sustain ecosystems, including supporting food webs. Threats to reptiles include habitat loss and environmental damage, invasive species, disease, pollution, exploitation, poaching, and global climate change.

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Habitat destruction is the greatest threat. As urban sprawl, overgrazing and desertification – which in turn lead to the expansion of forestry and agricultural operations – put increased pressure on the land, reptile habitats have been overtaken by humans, creating conditions for increasingly stressful for reptiles. Shrinking habitats increases edge effects – which are the effects of separating habitats (as with a road) so that animals cannot reach resources or mates in other parts of the habitat. Today, climate change is exacerbating these pressures. Since many reptiles are ectothermic – they cannot generate internal heat and instead rely on external conditions (e.g. sunlight) for warmth – temperature increases due to climate change affect them significantly. Many arid-climate reptiles (eg, lizards and geckos) are already experiencing extremely high temperatures, and minor increases could make their already limited habitats unlivable.

In addition, reptiles are particularly prevalent in regions of Southeast Asia, where disruptions in monsoon cycles can hinder the development of embryonic reptiles. Many species – turtles, crocodiles and alligators, for example – lay eggs in wet conditions. Newly dry and disturbed areas threaten their ability to survive, slow their development or growth, and distort natural selection of sex ratios.

The good news is that the methods implemented to protect other types of animals – reducing tropical deforestation, controlling illegal trade and improving agricultural productivity so that farmland does not need be extended – similarly benefit reptiles. However, the current crisis requires more action to improve conditions for reptiles in particular.

Readers should encourage their representatives to take action. Reptiles play a crucial role in Earth’s ecosystems, and concerted solutions have the potential to make all the difference.

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