Lizards from cold climates may face rapid extinctions in next 60 years, study shows

Lizards from cold climates may face rapid extinctions in next 60 years, study shows
The study looked at three groups of diverse lizards from South America. Credit: Daniel Pincheira-Donoso

Lizards that produce live young are significantly more likely to be driven to extinction through climate change than those that lay eggs, new research suggests.

The study, involving Nottingham Trent University and the University of Lincoln, suggests that live-bearing face high risks of extinction within the next 60 years, driven predominantly by rising temperatures.

Researchers investigated how strategies for reproduction that live-bearing (viviparous) or egg-laying (oviparous) modern lizards evolved in the past can affect their chance to survive caused by humans.

As part of the work, the team argue they have confirmed the emerging 'cul-de-sac' theory, which suggests that live-bearing reproduction evolved in lizards that colonized , such as high elevations and latitudes.

This adaptation, however, is dragging them to extinction.

The theory—developed by NTU's Dr. Daniel Pincheira-Donoso—suggests that following colonization of those harsh environments, mothers 'retained' the eggs in their bodies to act as incubators, and this provided embryos with stable conditions of temperature and oxygen.

It is thought that, over time, this egg retention evolved into birthing live young.

Reproducing live young is not very effective in hot environments, however, and once reptiles evolve in this way, they remain 'trapped' in cold areas.

As climate warming rapidly progresses towards higher elevations and latitudes, the 'suitable' cold climates where live birthing species live will be pushed towards and continent edges until lizards run out of space and are eventually wiped out.

The study looked at three groups of highly-diverse lizards from South America: one which only has viviparous species, one with only oviparous species, and one which has evolved both forms of reproduction.

To investigate whether ongoing climate change will cause extinctions predicted by the theory, the researchers used computational modeling of current change, combined with real data on the conditions that lizards live under.

Their team, led by Dr. Pincheira-Donoso, found that live-bearing species will displace towards the mountain tops at significantly faster speeds than egg-laying species—displacing at a rate of 0.3% of the current geographical range per year.

While this means that viviparous lizards will face high extinction risks within just six decades, oviparous species will remain largely unaffected. Of all the studied, temperature was the dominant factor responsible for these extinctions.

"Human-induced has forced the modern world to face one of the most severe periods of global-scale extinctions of species since life began," said researcher Dr. Daniel Pincheira-Donoso, a bioscientist at Nottingham Trent University.

He said: "Our results highlight the extent of the extinction crisis that modern biodiversity is currently facing. By 2080, more than half of the current 'cold lands' in the area we investigated in South America will have become warm, leading current resident species to extinction.

"Extinction risks are known to increase as a result of rapid climatic alterations and environmentally sensitive traits that fail to adapt to those changes.

"Viviparous lizards appear to have undergone a 'double-edged adaptation' – life births evolved because it was the critical adaptation that reptiles needed to colonize cold climates, but it will also accelerate their extinctions.

"This work provides us with an opportunity to identify specific areas that need more urgent protection—such as high mountain elevations where extinction risks will concentrate.

"This phenomenon would apply to other reptiles, such as snakes, anywhere in the world."

Researcher Manuel Jara, who was at the University of Lincoln when the work was carried out, added: "Live-bearing lizards are predicted to follow their dramatically shrinking cool habitats, increasing their risk of ."

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Lizards facing mass extinction, new research suggests

More information: Manuel Jara et al. Alternative reproductive adaptations predict asymmetric responses to climate change in lizards, Scientific Reports (2019). DOI: 10.1038/s41598-019-41670-8
Journal information: Scientific Reports

Citation: Lizards from cold climates may face rapid extinctions in next 60 years, study shows (2019, August 16) retrieved 19 September 2019 from
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Aug 17, 2019
Context? Forgetaboutit. You will not get context from researchers paid to find (or fabricate statistically) the assumed human signal in all the climate noise.

So here is the context: All creatures now extant are descended from the survivors of a much warmer climate regime than today's. At present, the climate is abnormally cold in geological terms. Lizards have survived hundreds of millions of years on this planet, and most of that time, it was MUCH WARMER than now -- we are in an Ice Age that began 1 million years ago. There have been warm spells such as now (interglacials) between periods of extreme cold. The multi-century recoveries from cold nadirs look just like ... (wait for it) "hockey sticks"; the current hockey stick recovery began about 15,000 years before present and peaked about 8,000 years ago. Orbital mechanics suggest the next millennium will be somewhat cooler, not boiling hot.

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