The cost and complexity of assessing impact

The idea was a simple one. Using EICAT impact assessments of alien amphibians, could we get the costs of the studies and see whether more expensive studies resulted in higher impact assessments? Or, perhaps more worryingly, were cheaper studies resulting in lower impacts of invasive species?

But this paper turned out to be a huge undertaking. 

First, my dedicated team of MeaseyLab amphibian fundis who were kicking their heals after the CIB ARM in November 2019, committed to scoring all unscored amphibians since we did the same exercise in 2015 (seehereif you aren’t familiar with that). Initially, we thought that this would be a short order, but we discovered that all those invasive amphibian people out there in the world had been working overtime. Specifically, they had generated about the same number of papers that we’d scored in 2015, but in only 4.5 years!

We drank a lot of coffee and all sat around together in my office to answer any potential queries regarding EICAT scoring of amphibians.

While James and Nitya certainly made the most noise, it turned out that Carla quietly did most of the assessments. 

After that first exercise, we started begging. We approached everyone who had published in the last 4 years with a paper that had resulted in one of our EICAT scores and we gave them a questionnaire to work out how much money they had spent on the project that had produced that paper.

The questionnaire was approved by Stellenbosch University ethic’s committee, and was given the green light by our economics Prof: Elizabeth Pienaar. 

Sharp eyed blog readers will recognise Elizabeth from the July 2019 postgraduate field trip where she taught her module on economics and invasive species (see here). Sadly, Elizabeth couldn’t join us in person, so we simply sent the data from all of our (very kind) contributors who had taken the time to produce costs for us. Their anonymity was assured. You know who you are, and we are very grateful for your help. We know that it was a big ask.

Once Elizabeth had converted all of those different currencies into some dollar price parity, we could run our models and see whether the price of the study predicted the level of EICAT impact for the amphibians.

Here comes the big reveal: 

Yes - it did!

This is actually quite shocking, as what it means is that if you don’t have a lot of cash you are unlikely to find that your invasive species has a high impact. It follows that if your sitting in a part of the world where you don’t have much cash, then it might be extra difficult for you to make your case that your invasive species is actually a big problem. 

Next, Nitya had the idea of looking at the complexity of these studies. Would studies that were more complex result in higher impact scores? He based the complexity on a new study by Christie et al (2019), who found that more complex designs resulted in more robust results. Nitya beavered away for several weeks scoring all of the papers. Finally, when they were all done, we were able to run our models. 

And we found that - yes again! More complex study designs were indeed likely to result in higher impact scores. 

This result goes hand in hand with our economic result above, as more complex study designs often cost more. 

So please do go and read all about it:

Measey J, Wagener C, Mohanty NP, Baxter-Gilbert J, Pienaar EF (2020) The cost and complexity of assessing impact. NeoBiota 62: 279-299.https://doi.org/10.3897/neobiota.62.52261

South African Post Office issues first day cover to commemorate Critically Endangered frogs

The South African Post Office has issued four stamps on a First Day Cover showing South Africa's endangered frogs and toads. These are all frogs from the south-western Cape that are notably linked to research from the MeaseyLab:

Rose's mountain toadlet is the subject of a growing number of publications: 

Tolley, K.A., De Villiers, A.L., Cherry, M.I., & Measey, G.J. 2010. Isolation and high genetic diversity in dwarf mountain toads (Capensibufo) from South Africa. Biological Journal of the Linnean Society 100, 822-834. https://doi.org/10.1111/j.1095-8312.2010.01469.x pdf

Cressey, E.R., Measey, G.J., & Tolley, K.A. (2015). Fading out of view: the enigmatic decline of Rose’s mountain toad Capensibufo rosei. Oryx, 49, 521–528. https://doi.org/10.1017/S0030605313001051 pdf

Edwards, S, Tolley, KA & Measey, GJ (2017) Habitat characteristics influence the breeding of Rose's dwarf mountain toadlet Capensibufo rosei (Anura: Bufonidae) Herpetological Journal27: 287-298. pdf

Channing, A., Measey, G.J., De Villiers, A.L., Turner, A.A. & Tolley, K.A. (2017) Taxonomy of the Capensibufo rosei group (Anura: Bufonidae) from South Africa. Zootaxa 4232(2): 282–292 https://doi.org/10.11646/zootaxa.4232.2.11 pdf

Becker, FA, Tolley, KA, Measey, GJ & Altwegg, RA (2018) Extreme climate-induced life-history plasticity in an amphibian. American Naturalist 191(2): 250–258. http://dx.doi.org/10.1086/695315 pdf

Measey, J., Becker, F. & Tolley, K.A. (2021) After the fire: assessing the microhabitat of Capensibufo rosei (Hewitt, 1926). Herpetology Notes14: 169-175. pdf

Becker, F., Altwegg, R., Slingsby, J., Measey, J., Tolley, K.A. (in press) Finding rare species and estimating the probability that all occupied sites have been found. Ecological Applications

Ebrahim, Z., De Villiers, A., Measey, J., (2020) Assessing water conditions for Heleophryne rosei tadpoles and the conservation relevance. Koedoe62(1), a1581. https://doi.org/10.4102/koedoe.v62i1.1581 pdf

Stark, D., Turner, A., van Rensburg, B.J. & Measey, J. (in press) Population estimation of a cryptic moss frog using acoustic spatially explicit capture recapture. Pages xx–xx in S.C. Walls and K.M. O’Donnell, editors. Strategies for Conservation Success in Herpetology. Society for the Study of Amphibians and Reptiles, University Heights, OH, USA. 

Once we've published work on this species, we'll have the complete set!

Laurie's new paper shows rapid adaptive shifts for invasive Xenopus to cooler France

In the first paper of her PhD, MeaseyLab student Laurie Araspin (jointly supervised by Anthony Herrel of the NMHN Paris) shows how adult Xenopus laevis introduced to France in the 1980s have already shifted their temperature dependence of locomotor performance.

The work has particular interest as it shows how rapid adaptations in invasive species allows them to function in different environments to that of their native range. In this study, Laurie used adults collected from the South African Cape and subtropical KwaZulu-Natal (watch a video of that collection here). Despite these massive differences in collection localities, once they were acclimated in the lab there was no difference in their performance. The French animals, however, maintained a massive difference left shift (to cooler temperatures) in their thermal performance. 

This is just the start of Laurie's exploration into the rapid adaptive physiological shifts shown by invasive populations of X. laevis when compared to their native South African populations. Despite COVID restrictions, Laurie's work continues in Paris and in 2021 we hope to have her in South Africa sampling some of the more extreme environments for African Clawed Frogs.

To read the paper in full:

Araspin, L., A. Serra Martinez, C. Wagener, J. Courant, V. Louppe, P. Padilla, J. Measey and A. Herrel (2020) Rapid shifts in the temperature dependence of locomotor performance in an invasive frog, Xenopus laevis, implications for conservation. Integrative and Comparative Biology   60(2):456–466 https://doi.org/10.1093/icb/icaa010 pdf  

MeaseyLab at the 7th Annual Meeting of the Canadian Herpetological Society

Drs Natasha Kruger and James Baxter-Gilbert both presented their work at the 7th Annual Meeting of the Canadian Herpetological Society online today. 

Perhaps the most remarkable event was that Natasha's talk coincided with local loadshedding (a South African term for a scheduled electricity blackout). Natasha then delivered the entireity of her presentation using her phone as a modem and with a flashlight on her desk. Super impressive!

 

There was a great shuffling of seats and reaching for (Canadian) beer when Natasha settled down to give her presentation on perceptions of predators for invasive African Clawed frogs in France

Then James provided his overview on the rapid exolution of size in invasive island populations of Guttural Toads:

James and Natasha during the meeting with their fellow delegates

...and who could forget how James dressed up for his travelogue. All in the name of the show folks...

All about Indian Bullfrog invasions

Sometimes is great to have all the information in one place, and here we can see a great example of this with a synthesis of research on the Indian Bullfrog by Nitya Mohanty. In this study, Nitya partnered up with Angellica Crottini who had extensive data about the bullfrog invasion on Madgascar, and Raquel Garcia who introduced the SDM modelling know how. 

In this paper, Nitya suggests that these bullfrogs are potential problems in more parts of the world, should they be introduced there. This is an important lesson in a time when we are still seeing the intentional introduction of American Bullfrogs for farming in different parts of the world.

Hopefully, this publication will highlight the potential problems of the Indian Bullfrog, and it won't end up being introduced to lots more places.

Read the entire article here:

Mohanty, N.P., Crottini, A., Garcia, R.A. & Measey, J. (in press) Non-native populations and global invasion potential of the Indian bullfrog Hoplobatrachus tigerinus: A synthesis for risk-analysis. Biological Invasions https://doi.org/10.1007/s10530-020-02356-9 pdf