From the UNIVERSITY OF EXETER and the department of “likely headed for Retraction Watch” comes this study that doesn’t seem to pass the smell test, because putting lizards in hot boxes isn’t the same as lizards in the wild, and the diurnal variation of temperature far exceeds 2-3°C. More likely, the lizards are reacting to stress from the environment, and have less bacteria because they’ve been isolated from their normal exposure to microorganisms.
Climate change could threaten reptiles by reducing the number of bacteria living in their guts, new research suggests.
Scientists from the University of Exeter and the University of Toulouse found that warming of 2-3°C caused a 34% loss of microorganism diversity in the guts of common lizards (also known as viviparous lizards).
In the experiments, lizards were put in temperature-controlled enclosures and samples of their gut bacteria were tested to identify which bacteria were present.
The diversity of bacteria was lower for lizards living in warmed conditions, and the researchers found this had an impact on their survival chances.
By raising the temperature by 2-3°C in their experiment, the researchers reflected warming predicted by current climate change models.
“Our research shows that a relatively small rise in temperature can have a major impact on the gut bacteria in common lizards,” said Dr Elvire Bestion, of the Environment and Sustainability Institute on the University of Exeter’s Penryn Campus in Cornwall.
“More testing is now needed, and it is highly possible that we will see similar effects in other ectotherms (cold-blooded animals such as reptiles and amphibians which depend on external sources of body heat).
“Given the importance of bacteria to digestion, it is crucial that more research is now carried out to investigate this overlooked effect of climate change.”
Climate change is now considered as the greatest threat to biodiversity and ecological networks, but Dr Bestion said its impacts on the bacteria associated with plants and animals remain largely unknown.
“We are only now starting to understand the importance of gut microbiota in the physiology of all species, including humans,” she said.
“These bacteria are linked to everything from digestion to immunity and obesity.
“The gut is the latest health craze in humans – with everything from probiotic yoghurts to faecal transplants being marketed – but almost no studies have been done on how the changing climate will affect these microbes.”
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The paper, published in the journal Nature Ecology and Evolution, is entitled: “Climate warming reduces gut microbiota diversity in a vertebrate ectotherm.”
Added: (referenced in my comments below), the press release: https://www.eurekalert.org/pub_releases/2017-05/uoe-gwk050517.php
Added: best comment of the thread –
I’m not a biologist by trade, but I do keep extremely rare lizards as pets (legally – a difficult but not impossible thing if you have enough money). I’m also involved with conservation (because I care), and so there is plenty of interaction with academic biologists and practicing zoologists as well as private individuals who share my hobby. I haven’t read the details of this experiment, so this is off-the-cuff commentary on the scientific environment, not the specifics of the experiment per se.
1) Academics trust other academics way too much – even the sketchiest of conclusions sometimes wind up being taken as gospel, to the point where I sometimes wonder what freaking planet they live on because it’s not this one.
2) Academics gravitate towards disaster scenarios. Any change horrifies them. Optimism about change in the environment is treated as religious delusion (bask in the irony of that for a moment, please). I’m an atheist, and some of the conversations I have with academic scientists are just as strange and uncomfortable for me – in the exact same way – as dealing with deeply religious people (if that’s your thing, then that’s your thing – I don’t hate or dislike you, but I do think it’s weird. You’re perfectly free to think I’m weird too. It’s cool. We can still get along). This doesn’t mean there aren’t plenty of bad-to-awful changes, but there are far more predictions of strongly negative outcomes than there are actual negative outcomes of any magnitude.
3) Nature adapts extremely well. This is probably why the Earth isn’t a barren rock right now, because plenty of things (of which human activity is some tiny sliver of 1%) have tried to kill us all. Our captive animals do “scientifically impossible” stuff on a regular basis. Of course, it’s not really “scientifically impossible,” it’s just that the conclusions they are violating were arrived at without much actual science taking place.
4) Lizards adapt better than most. Freakishly well. There are plenty of people that do a downright awful job of keeping lizards as pets and it doesn’t kill the animals. The common belief that lizards are boring pets is largely based on the fact that most lizards kept as pets are half dead – and they can stay that way for years (all the necessary info is available for free on the Internet, so no excuses for these idiots). With proper care they are quite vibrant and interactive animals, with a surprising amount of personality. In any case, if I had a dime for every time a so-called scientist told me that a 2º-5º C change in environment temperature (or similarly small changes in humidity, UV light exposure, etc) would be the end of the lizard world and I already knew for a fact that people were keeping very healthy animals (as far as we can measure, and we do) with those changes… I could afford to buy a lot more lizards.
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Added: comment from Rud Istvan suggests the paper is fatally flawed
Paper is paywalled, but read the SI, which gives some big clues as to what is actually going on. There were three sets of 3 ‘Metratron’ 100m2 semi outdoor enclosures, all supposedly identical in plants and food invertibrates. Controlled for moisture and temp, netted to prevent predation. Three each for Present climate ‘PC’ avg june-sept temp 26.6C, peak 29.5C, intermediate ‘IC’ J-S avg 28.2 peak 31.5, and warm ‘WC’ avg 28.4 peak 32.1. All stocked June 2012 with near identical numbers (~30) of adult and juvenile matched sex ratio wild caught lizards. Left for 1 year, but only the summer months June -Sept had IC or WC. the fall, winter, and spring were PC in all nine enclosures.
All the surviving lizards were caught May 2013 and the cloaca sampled for bacteria. But they ended up having to exclude the IC group from the final analysis, because in one of the IC enclosures only 3 lizards survived the year. The SI specifically says that the reduced WC gut flora had TWO causes: 2-3C, and higher mortality. They therfore don’t know The temperature impact alone because of the mortality difference.That detail never made it to the abstract or the PR.
Looked up other papers on lizard microbiomes. (Weird, two in 2017 already.) Turns out captivity by itself changes microbiomes. Turns out that in the wild, there is a significant degree of individual variation depending on accidental juvenile diet, which is mainly how lizards pick up the bacteria from the insects they eat. Now the experimental method for this paper simply threw all the PC or WC samples together for genetic analysis to identify all the bacteria in all the lizard cohort. The reported 34% reduction in WC microbiome gut flora species compared to PC could simply be from fewer surviving individuals, so automatically less bacterial diversity.
Without controlling for mortality and individual lizard bacterial diversity, this pseudoresult is just more junk climate science.