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Turtles with unique features are most likely to go extinct

Turtles and crocodiles are two of the most endangered animal groups on Earth, with about half of these species currently threatened. To inform conservation efforts, it is crucial to gain a better understanding of which species are currently facing the highest risk of extinction and why.

Now, a team of scientists led by the University of Oxford has found that the most endangered turtle and crocodile species are those that evolved unique life strategies, or ways of dividing their resources and energy for survival, reproduction, and growth. Such species usually play highly specific roles in their ecosystems – including seed dispersal, creating habitats for other species by making burrows, or acting as predators that help maintain balance in their ecosystem – which are unlikely to be replaced by other species if they disappeared.

The experts used state-of-the-art models to simulate extinctions caused by human-led threats to assess how species with different life strategies might be impacted. “A key finding is that the threats do not affect all species equally; they tend to impact particular life history strategies. For example, unsustainable consumption of turtles and crocodiles mainly affects the longest-lived species with the largest clutch sizes, such as sea turtles,” explained senior author Rob Salguero-Gómez, a biologist at Oxford.

The analysis revealed that, if all critically endangered species of turtles, tortoises, and crocodiles went extinct, 13 percent of unique life strategies would be lost. Currently, major threats to all of these species include habitat loss, climate change, and global trade, while species with unique life strategies are also particularly affected by unsustainable local consumption, diseases, and pollution. 

For instance, turtles and crocodiles with “slow” life histories – characterized by late maturity and low numbers of offspring – are particularly vulnerable to threats from invasive species and diseases, while species with high reproduction output (higher clutch sizes), such as freshwater turtles and saltwater crocodiles, face significant threats from pollution and unsustainable local consumption.

“The main threat to the viability of these groups of reptiles is habitat loss and fragmentation, which is especially common in species inhabiting the Northern hemisphere. The disappearance of wetlands, increasing urbanization, and the development of intensive agriculture, which already have tangible effects, will likely continue to negatively affect these species and their ability to persist in the mid- to long-term,” said lead author Roberto Rodriguez, a biologist at the University of Alicante who conducted this research during a fellowship at Oxford.

These findings highlight the urgent need for effective management strategies to protect species overall, while paying particular attention to those with unique life history strategies, whose functions would be most difficult to replace in their ecosystems. Citizens willing to help protect these animals should refrain from purchasing products made from them, support organizations involved in conservation projects, perform responsible ecotourism, and engage in citizen science activities.

The study is published in the journal Nature Communications.

By Andrei Ionescu, Staff Writer

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