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http://www.usgs.gov/newsroom/article.asp?ID=2696

Technical Announcement:
Challenges identified in using models to predict snake and other animal invasions
Released: 2/9/2011 5:00:00 PM

FORT COLLINS, Colo. — New research published today has identified challenges in using computer models to predict the potential of pythons or other invasive vertebrate species to spread across portions of the United States, according to the U.S. Geological Survey.

The study, published in PLoS One, assesses the accuracy and limitations of the MaxEnt modeling program for climate matching when applied to predicting the potential risk of vertebrate invasions in the U.S., especially pythons.

Climate matching for invasive species is the process of using climate data from a species’ native range to identify areas that are climatically similar outside of that range and which could be at potential risk for invasion.

A previous paper by USGS researchers Gordon Rodda, Catherine Jarnevich and Robert Reed published online in 2008 in the journal Biological Invasions used a rule-based model and had estimated climatic suitability for Burmese pythons to extend roughly over the southern third of the U.S.

After the Biological Invasions article was published, another group of scientists (Pyron et al.), from the City University of New York (PLoS One, 2008) used MaxEnt, a different climate-matching system, to re-assess the potential for invasion in the U.S. Their results contradicted the USGS 2008 conclusions by asserting that Burmese pythons posed a risk only to the area already occupied by this invasive species in southern Florida.

However, the new USGS research published today concluded that the Pyron et al. study incorrectly applied the MaxEnt modeling program and used some erroneous data. USGS researchers found that when Pyron et al. used MaxEnt's default (pre-set) settings, the model results predicted only very limited climate suitability for the species in Florida and in extreme south Texas. However, when USGS researchers (2011) ran the model again using more appropriate settings (such as limiting the number of parameters and limiting background data to the native range rather than global), it showed a greatly expanded area at risk, including much larger portions of the southern United States from California to South Carolina and many island territories.

USGS authors realized that Pyron et al. accidentally introduced errors such as using a dataset that included erroneous records for a different species of python. When the USGS authors removed these records and repeated the Pyron et al. analysis, different results were obtained, indicating the instability of the model when used in this manner.

Pyron et al. also used about 60 parameters in their models, although the most current guidance for doing these kinds of predictive models recommends that only about 10 parameters should have been used.

“When a model is excessively complex, it has a poor ability to accurately predict invasion risk,” said Gordon Rodda, the lead author of the study. “An excessive number of parameters means that each additional one acts as a filter, and using too many filters means that many sites that are truly at risk of python establishment get filtered out. In this case,” he added, “Pyron et al. incorrectly rejected many sites in the United States that may well have climate suitable for Burmese pythons.”

The new research also highlights the need for scientists to consider that factors other than climate – such as predators, disease or habitat -- may – and often do -- limit a species’ distribution. For example, said Rodda, when a potential invader is released in a new country, predators, diseases and other factors that limit the species’ population numbers in its homeland may not be present in the new place.

“This means the invader’s population may be able to expand into a larger area,” Rodda noted. “As a result, the areas at risk of invasion often extend to climate specifics not found in the native range boundaries. For example, the finding that heavy monsoons are present in the native range does not necessarily mean that a species requires monsoonal downpours to thrive.”

Adhering to the guidelines laid out in this paper and others for using MaxEnt produces more reasonable models. MaxEnt, when used appropriately, can produce useful models. The models for this paper were produced at the Resource for Advanced Modeling (RAM) at the USGS. Expertise at the RAM provides an environment for scientists and managers to carefully implement models such as MaxEnt and assess invasion risk.

The new study, Challenges in identifying sites climatically matched to the native ranges of animal invaders, is authored by Rodda,

Alex Pyron's a prodigy...a PhD and still in his early 20s. I don't have the paper in front of me, but as I recall, his "erroneous species" Rodda crows about was really just limiting the data set to the specific subspecies of Python molurus present in Florida, which is the more tropical of the subspecies extant in its home range.

It sounds like Rodda is scrambling to show HIS data is "more correct." He correctly asserts that factoring in more variables into a model limits the range, because the real world has more variables than the "maximum recommended" 10 he suggests using.

The vibe I get is that he's working to make the data fit his narrative/agenda, bringing out the "no natural predators" wild card, etc.
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Chris McMartin
www.mcmartinville.com
I'm Not a Herpetologist, but I Play One on the Internet

Thanks Chris for setting it strate. I dont think we will see that anywhere else. VM

Thanks Chris for setting it strate. I dont think we will see that anywhere else.

Don't take my word for it blindly...I could have the content of the paper all wrong. I'd look it up, but I'm away from home on business on an exruciatingly slow internet connection (kingsnake takes almost a minute to load a page!).

But I did meet Alex a couple of years ago. Reminds me of Doogie Howser!

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Chris McMartin
www.mcmartinville.com
I'm Not a Herpetologist, but I Play One on the Internet

"it showed a greatly expanded area at risk, including much larger portions of the southern United States from California to South Carolina and many island territories. "

South Carolina? Really? Did someone forget to tell him there are a few dead pythons that say otherwise?

>>"it showed a greatly expanded area at risk, including much larger portions of the southern United States from California to South Carolina and many island territories. "
>>
>>South Carolina? Really? Did someone forget to tell him there are a few dead pythons that say otherwise?

That's the problem. These guys can say anything they want, no matter how ridiculous, with no fear of negative consequences. Why even do real life experiments anymore? It's absolutely disgraceful. I don't know how these guys can call themselves scientists and sleep at night.

His partner in Crime,R. REED MS PhD was the keynote speaker at the 17th Conf.of Reptilian & Amph. VETERINARIANS. "The lecture was Fascinating,disturbing and educational" D.M Mader M.S DVM,DABVP.said in Reptiles mag.p16 4-2011.(?). He was fair and unballenced stating some objected to the results of the study. SOME OBJECTED! No words on the objections of the study. How about,your 15 yrs.old, had pythons and Boas for a year or two,and well you know, ITS PHONY. But you see even though in the end it will hurt their own pay check, He's the keynote speaker,! and he was fascinating! How about He was chasted out of the building by an angry mob of Veterinarians who give a damn about their own freedom. Oh, but please dont hurt the earth. Vic Morgan F.O.S (freedom orientated solutions)

What Rhoda is basically saying is that his climate study is worthless, alone as a determinate for python spread.

He dismisses the other study as having too many variables that exclude the spread...while at the same time saying his study alone is irrelevant and only hypothetical theory babble.

The context of his comments are undeniable. When people are too smart for their own good...

jsc
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"As hard as I've tried, just can't NOT do this"
John Crickmer

“An excessive number of parameters means that each additional one acts as a filter, and using too many filters means that many sites that are truly at risk of python establishment get filtered out.”

Apparently, real world scientific data and observations do not seem to matter anymore. This is very clearly a concerning predetermined conclusion at play here when Rodda/Reed would suggest using only 10 parameters based on the guidance of a computer model, rather than 60 real world parameters as used in the Pyron study to determine the Burmese python distribution.

If Rodda and Reed's model were in fact, correct in this time frame, than we should be seeing pythons thriving in the Carolinas, the Gulf Coast states, Texas, accross the Sonoran desert, and over California and even into the west coast of Canada and Alaska by now.

"If Rodda and Reed's model were in fact, correct in this time frame, than we should be seeing pythons thriving in the Carolinas, the Gulf Coast states, Texas, accross the Sonoran desert, and over California and even into the west coast of Canada and Alaska by now."

Not to mention indigenous species. Are any of them expanding their ranges northward?
One of the species proposed for Lacey Act listing happens to be Boa constrictor, which historically has ranged to within 200 miles of the Texas border. Have they expanded their range into Texas or beyond yet?

They also was not counting that we (herp. nation.)would be able to prove (with dna.Barker*) that the Pythons in question were not the Indian ssp. They thought that would slip right by. Its grandis larrecin! VM

quote "Apparently, real world scientific data and observations do not seem to matter anymore. This is very clearly a concerning predetermined conclusion at play here when Rodda/Reed would suggest using only 10 parameters based on the guidance of a computer model, rather than 60 real world parameters as used in the Pyron study to determine the Burmese python distribution.
"endquote

Actually, this is exactly what I expected to come from Rodda et al.. and unfortunately this is playing out exactly as should be expected.

Rodda's original paper wasn't subjected the normal peer reviewed process and was not challenged before publication because of this loophole. Subsequent responses and studies have poked holes into the premise by Rodda et al. Rodda et al are responding with what they consider flaws in the studies that cast doubt on thier results... and are using that to support thier original premise. The next round will be responses back against this response by Rodda etal to thier results. As facts are defended or refuted, there will be accumulating evidence which will eventually completely reject Rodda etal's premise on the threat posed by the snakes. If all that is needed to refute this response by Rodda is to rerun the model using only the conditions for bivitattus then that is going to be a simple refute to Rodda et al.
Where it is a problem is that Rodda et al can use USGS to release the results without going through the peer reviewed process where the researchers outside of USGS have to go throgh the process which can be significant period of time.

As a very very extreme example of the time line it can take to fully refute bad research, look at how long it took to show that the original study on autism and vaccinations to be totally refuted and how many people refuse to accept the results...

Ed

http://www.cnah.org/pdf_files/1030.pdf

Here's a synopsis: Using Rodda's limited variables (he only used temperature and rainfall), Pyron et al plugged in information for the python's KNOWN range, and the model got it all wrong (showed the python should be far more wide-ranging in its native habitat than it actually occurs--including THE ARABIAN PENINSULA). Then they used additional climate parameters (such as temperature extremes the pythons experience, not just averages) and achieved a closer match to the known Python molurus range. Using these same parameters, when they re-mapped the US for potential range expansion, the result was "southern FL and TX."

Pyron and co. were careful to say this revelation shouldn't downplay the harmful aspects of invasive species; just that you need to be diligent in analyzing climate data.

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Chris McMartin
www.mcmartinville.com
I'm Not a Herpetologist, but I Play One on the Internet

Bottom line is --- Rhoda has just admitted his study is irrelevant in the real world with all of it's inherent caveats and hypotheticals.

jsc
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"As hard as I've tried, just can't NOT do this"
John Crickmer

Rodde is just CYA.

Rodda says "“When a model is excessively complex, it has a poor ability to accurately predict invasion risk,” said Gordon Rodda, the lead author of the study. “An excessive number of parameters means that each additional one acts as a filter, and using too many filters means that many sites that are truly at risk of python establishment get filtered out. In this case,” he added, “Pyron et al. incorrectly rejected many sites in the United States that may well have climate suitable for Burmese pythons.” "

He is saying that his moronic model is LACKING localities that the burms can invade.

While in one breath he says too many filters increases chances for error. in the next he says we left out many localities...

In the face of the recent weather and near wipeout of Burms in south Florida, he is saying they are MORE invasive than previously thought.

Hey Tom C! Did the cold weather this year leave any burms around? I'd think they'd be dead before they can reproduce, thus extinguishing the population.