Thursday, March 7, 2013

Liolaemus & Climate Change

Liolaemus tenuis in Maipo Canyon, Chile (near San Alfonso). Photo credit: Kaldari

The following pres release from the University of  Lincoln describes research on the genus Liolaemus, a clade of lizards restricted to southern South America.  It holds about 230 species, nine of which were described during 2012. Many of these lizards have adapted to high elevations and the long cold season associated with them. In the process, they have been able to switch their mode of reproduction from live-bearing to egg-laying many times. The forthcoming paper has been published early on-line and a link to the abstract is at the bottom of the page.

Climate change could lead to dozens of lizard species becoming extinct within the next 50 years, according to new research published this week.

Globally it has been observed that lizards with viviparous reproduction (retention of embryos within the mother’s body) are being threatened by changing weather patterns. A new study suggests that the evolution of this mode of reproduction, which is thought to be a key successful adaptation, could, in fact, be the species’ downfall under global warming.

Dr Daniel Pincheira-Donoso, from the School of Life Sciences at the University of Lincoln (UK), is the lead author of the paper detailing these amazing predictions, published in the scientific journal Global Ecology and Biogeography.

Researchers, including academics from the University of Exeter, investigated the hypothesis that historical invasions of cold climates by Liolaemus lizards – one of the most diverse groups of vertebrates on earth – have only been possible due to their evolution to viviparity (live birth) from oviparity (laying eggs). Remarkably, once these species evolve viviparity, the process is mostly irreversible and they remain restricted to colder climates.

By analysing this evolutionary transition in the lizards’ reproductive modes and projecting the future impact of climate change, the scientists discovered that increasing temperatures in the species’ historically cold habitats would result in their areas of distribution being significantly reduced. As a consequence, if global warming continues at the same rate, viviparous lizards are facing extinction in the next few decades.

Dr Daniel Pincheira-Donoso is one of the few people in the world who works on the ecology and evolution of these lizard species.

He said: “Lizards’ reproduction is largely linked to climatic temperatures and viviparous species are usually found in cold environments. When reptiles initially moved to colder areas they needed to evolve emergency measures to succeed in these harsh places, and we believe viviparity is one of these key measures. However, this transition is mostly one-directional and unlikely to be reversed. Rapid changes in the environment’s temperature would demand rapid re-adaptations to secure the species’ survival. Through the research we found that over the next 50 years nearly half of the area where these species occur may disappear, causing multiple extinction due to climate change.”

Overall the conclusion is that although viviparity allowed lizards in the past to invade and adapt to live in cold environments, and was therefore a key trait for evolutionary success, it will now ultimately lead to multiple events of extinction.

Dr Pincheira-Donoso said: “These lizards are one of the most diverse groups of animals, and are able to adapt to remarkably diverse conditions. Unfortunately, a reduction in cold environments will reduce their areas of existence, which means that their successful evolutionary history may turn into a double-edged sword of adaptation. Their extinction would be an atrocious loss to biodiversity.”

Dr Dave Hodgson, from the University of Exeter, said: “Climate change must not be underestimated as a threat to modern patterns of biodiversity. Our work shows that lizard species which birth live young instead of laying eggs are restricted to cold climates in South America: high in the Andes or towards the South Pole. As the climate warms, we predict that these special lizard species will be forced to move upwards and towards the pole, with an increased risk of extinction.”

Citation
Pincheira-Donoso, D., Tregenza, T., Witt, M.J. & Hodgson, D.J. The evolution of viviparity opens opportunities for a lizard radiation but drives it into a climatic cul-de-sac. Global Ecology and Biogeography, 2013

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