Posted on 03/12/2019 11:32:50 AM PDT by ETL
An Iowa State University biologist is sounding the alarm for the painted turtle, one of many reptiles for which climate change could prove particularly threatening.
Fluctuations in temperature driven by climate change could devastate a range of species for which sex is determined by temperature during critical stages of development, according to recently published research led by Nicole Valenzuela, a professor of ecology, evolution and organismal biology. Rising temperatures, along with wider oscillations in temperature, could disrupt the ratio of males to females in painted turtle populations and threaten the survival of the species, Valenzuela said. The study was published in the peer-reviewed journal Scientific Reports.
Painted turtles undergo temperature-dependent sex determination while developing inside the egg. Eggs exposed to warmer temperatures tend to produce females, while cooler temperatures tend to produce males, Valenzuela said. Numerous turtle species – as well as crocodilians, some lizards and the tuatara – undergo temperature-dependent sex determination. And increasing average temperatures combined with stronger thermal fluctuations that result from climate change could lead to drastic shifts in the demographics of those species, she said, eventually leading to population collapse and possibly extinction.
Valenzuela and her coauthors exposed eggs from Iowa to temperatures recorded in nests from three different painted turtle populations in Iowa, Nebraska and Canada from which the proportion of males and females was also recorded. Valenzuela said that allowed the experiments to compare the responses of multiple painted turtle populations, which revealed that not all populations exhibit the same sensitivity to temperature.
Valenzuela's previous studies exposed turtle eggs to constant temperatures in a laboratory to gauge the impact on sex determination, finding that an increase of about 4 degrees Celsius can mean the difference between a nest that produces only males and a nest that produces only females. But those experiments failed to account for the fluctuations nests encounter in the wild. Follow up studies with the simplest possible fluctuations (cycles of 12 hours 5 degrees Celsius above and 12 hours of 5 degrees Celsius below those constant values) caused sex reversal, or the process of some eggs producing males despite warmer average temperatures. Valenzuela hoped that if similar fluctuations caused sex reversal in natural nests, it could counter the effect of warmer temperature averages, alleviating the effects of climate change.
Valenzuela's most recent experiments found this not to be the case, however. In a lab experiment that exposed eggs to temperature fluctuations mimicking conditions found in nature, and to conditions in which the oscillations were exaggerated to mimic climate change scenarios, the researchers discovered the trend still points toward nests producing a high proportion of females. The research showed that cooler temperature profiles that would tend to produce males trended toward females when the temperature fluctuations intensified. Embryos from warmer profiles, on the other hand, remained female or died when the fluctuations intensified.
"If what we found is generalizable to other species with temperature-dependent sex determination, this is bad news," she said. "If an average increase in temperature is accompanied by greater variance, we'll see populations becoming unisexual faster than anticipated. The greater oscillations add to the effect of just higher average temperature."
Valenzuela said loss of habitat and exploitation has already left many turtles vulnerable to extinction, and climate change only adds to the peril these species face.
"The whole message here is the potential effects climate change can have on these species and the importance of our findings for conservation," she said. "Turtles are the most vulnerable group of vertebrates, and many use temperature-dependent sex determination."
Explore further: Warming temperatures threaten sea turtles
More information: Nicole Valenzuela et al. Extreme thermal fluctuations from climate change unexpectedly accelerate demographic collapse of vertebrates with temperature-dependent sex determination, Scientific Reports (2019). DOI: 10.1038/s41598-019-40597-4
Journal reference: Scientific Reports 
Provided by: Iowa State University
Ultimately we’re paying for this garbage.
First, if the only output is “something could happen IF climate change”...then we can do this all day long on any animal or topic.
What I REALLY want to know is if the Ecuadorian Aquatic Rat will survive!!!!! ;p
Re: post 22
He’s washing the ‘paint’ off
The article also fails to mention that the painted turtle has a 50 year lifespan.
What the chances that the temperatures will consistanantly remain high or low every year at breading time for this species so that any given female will produce only clutches of one sex?
Let alone that all the females in a given population will produce only one sex for her lifetime.
Alarm-ism at its most ridiculous extreme.
Around 1959-1961, I had a pet gopher. I painted my name on his shell. He was so tame that I could pat on his hole and it would come out. I would play with him a while then put him back.
I think it is illegal to paint them now.
Acetone turtles don’t mind at all.
There’s an older study than this....circa 2013. Nothing new. Should this really be charged to global warming? Or is it just a blind eye to everything else.
“You don’t get the clearcoat, you’re gonna have corrosion problems.”
His real life wife is one of the indicted ones in the college admissions scandal........................
Well, he'd best not flee the interview.
I love that movie and watch it whenever it’s on.
The one thing that never makes sense is the part where she has dinner in St. Paul(?) with an Asian guy who was in love with her in HS. Seemed to be a ‘filler’ side story just to kill time.................
So do not paint your turtles.
Could, might, maybe, possibly, and they present it all with the breathless excitement as if it’s fact and a done deal.
Hasn’t climate always changed?
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.
