Blog

Natasha defends her PhD thesis (unofficially in Stellenbosch)

14 February 2020

Natasha defends her thesis

Doing a thesis defense is always a bit nerve wracking, but imagine if you had to do it twice? Luckly, for Natasha, it turned out that she did only have to defend her thesis once, but after we'd organised a defense in Stellenbosch, we decided to go ahead with the defense as a good practice for the real defense in Lyon. Whether or not it was actually going to be a defense seemed to be beyond our control. The faculty flip-flopped several times on the issue.

Then, at the last minute it looked like even the dry run wouldn't happen as we were forced out of our building for a small fire on the first floor.

Lots of people turn out to control the fire

We got back into the department shortly after 13h00, when the defense was due to start. We had a diminished audience as many people had disappeared during the evacuation, but all of the important people were there to listen.

Natasha Kruger defends thesis in Stellenbosch (informally)

In time honoured fashion, after the defense, the lab all went down to the pub to celebrate.

Natasha in the pub

Lab Xenopus

Pasha Podcast

12 February 2020

John M

The Conversation releases Pasha podcast on listening to frogs

Many of you will be aware of The Conversation: Africa. An online magazine that publishes popular articles written by academics.

Click on the link above and listen to the 6 minutes of pure gold...

aSCR Frogs

When is a wild animal actually a farm animal?

29 January 2020

John M

Can Wild Animals Actually be Farm Animals?

In a recent opinion piece led by Mike Somers, we criticised the SA government's Department of Agriculture for passing a bill that classified 24 indigenous wildlife species and 3 invasive alien species as 'farm animals'. This allows farmers to breed these same species into genetically pure lines that could be advantageous for their sale. However, this law contravenes several existing laws that conserve these same species, or list them as invasive in South Africa. Our article questioned whether such a law should ever have been promulgated, given that there was never any consultation.

Read the article in the South African Journal of Science here:

We got a nice write-up in the Guardian here:

And another write up in the Saturday Star here:

Saturday Star (1 Feb 2020)

...and the Witness here:

Witness 31 January 2020

Lab

Four talks at SICB

07 January 2020

John M

Three different talks for Society for Integrative and Comparative Biology (SICB) 2020

Annual Meeting of the Society-for-Integrative-and-Comparative-Biology (SICB)

Austin, Texas USA: JAN 03-07, 2020

Challenges of the invasion front water balance, stress and immunity in the Guttural toad

P3-44 Monday, Jan. 6 Challenges of the invasion front: water balance, stress and immunity in the Guttural toad BARSOTTI, AMG; MADELAIRE, CB*; WAGENER, C; TITON JR , B; GOMES, FR; MEASEY, J; University of São Paulo; Northern Arizona University; Stellenbosch University; University of São Paulo; University of São Paulo; Stellenbosch University cmadelaire@yahoo.com.br

Species introduced by human activities may comprise many ecosystems, however, some species may become invasive and rapidly expand their population size, indicating that these species have an adaptive capacity to new environments. In South Africa, the bufonid species Sclerophrys gutturalis was introduced in a periurban area with colder and drier climatic characteristics from those in which native populations occur. Our goal was to understand the adjustments made by this species in its new environment in terms of stress physiology and immunity. We assessed corticosterone (CORT), neutrophil:lymphocyte ratio (N:L), bacterial killing ability (BKA) and hematocrit (Htc) basal and after standardize stressors (dehydration and movement restriction), as well as body condition index (BCI) and field hydration level, in males from the native (Durban) and invasive population (Cape Town). Individuals from the native population presented higher basal BCI and BKA and lower N:L ratio. After the experiment, the native population presented higher BKA than the invasive population. Individuals from both populations showed increased CORT after dehydration. The results show that the native population presents higher immunocompetence and BCI, indicating a better conditions when compared to the invasive population. Dehydration represented stress for both populations, increasing CORT levels. Thus, our results corroborate that the BCI and dehydration level can generate major impacts on the physiological processes for this species.

Invasive toads shift behavioral traits to find water

43-7 Sunday, Jan. 5 09:15 – 09:30 Invasive toads shift behavioral traits to find water MADELAIRE, CB*; BARSOTTI, AMG; WAGENER, C; SUGANO, Y; BAXTER-GILBERT, J; GOMES, FR; MEASEY, J; Northern Arizona University; University of São Paulo; Stellenbosch University ; University of São Paulo; Stellenbosch University; University of São Paulo; Stellenbosch University cmadelaire@yahoo.com.br

The adaptive nature of invasive species is becoming recognized as facilitating their survival in conditions that differ from their native range. Behavioral changes in invasive populations have been poorly explored but offer a wide potential when combined with physiological traits. For anurans invading xeric habitats, the importance of finding water is relevant for reproduction, to maintain hydration to function optimally and not experience dehydration stress. The water-finding hypothesis (WFH) states that survival can be enhanced through the behavioral ability to find water. We tested the WFH in Sclerophrys gutturalis from their native population in Durban and an invasive population in Cape Town Additionally, we tested if artificially elevated levels of corticosterone (CORT), which is known to increase during dehydration stress, affect water-finding behaviors. In a labyrinth experiment, we observed the toads’ ability to find water in different hydration states (100%, 90% and 80%). We found that individuals from the invasive population took longer to engage in water-searching behavior and spent more time near to the water source after finding it. Also, toads from the invasive population were more active and at 90% dehydration they show higher number of attempts to find water. Moreover, elevation of CORT in fully hydrated toads increased the success of finding water. Our experiment suggests that rapid adaptative water-finding behavior might facilitates survival of an invasive anuran in a xeric habitat. Additionally, we suggest a link between elevated CORT levels and water finding success. Our results lend support to the importance of adaptive behavior in successful invasions and the modulation of water-finding behavior by CORT.

Rapid Local Adaptations in an Invasive Frog (Xenopus laevis) the Importance of Functional Trait Measurements to Predict Future Invasions

S9-6 Monday, Jan. 6 10:30 – 11:00 Rapid Local Adaptations in an Invasive Frog (Xenopus laevis): the Importance of Functional Trait Measurements to Predict Future Invasions. HERREL, A*; ARASPIN, L; PADILLA, P; COURANT, J; SERRA MARTINEZ, A; REBELO, R; IHLOW, F; BACKELJAU, T; MOKHATLA, M; GINAL, P; RöDDER, D; MEASEY, J; CNRS/MNHN, Paris, France; CNRS/MNHN, Paris, France; CNRS/MNHN, Paris, France; CNRS/MNHN, Paris, France; CNRS/MNHN, Paris, France; Uuniversity of Lisbon, Portugal; ZFMK, Bonn, Germany; RBINS, Brussels, Belgium; Stellenbosch University, South Africa; ZFMK, Bonn, Germany; ZFMK, Bonn, Germany; Stellenbosch University, South Africa anthony.herrel@mnhn.fr

The control and eradication of invasive species is an ever-increasing problem for wildlife management and conservation practitioners. Understanding the potential future spread of invasive species is critical to inform management decisions. One often used tool to predict future species distributions is species distribution modelling (SDM) under alternative scenarios of climate change. Although extremely relevant and insightful, most of these models suffer from two drawbacks: 1) the lack of physiological data describing the dependence of organisms on changes in temperature and hydric state; 2) they ignore any potential for adaptive differentiation of invasive populations. To test what the effect could be of these two parameters we focused on invasive populations of the invasive amphibian, Xenopus laevis. We collected data on anatomy and physiology (temperature dependence of performance traits) for animals from the source population as well as invasive populations. These data were then used to inform SDMs that predict future spread under different climate change scenarios and to test for the potential adaptive divergence of invasive populations relative to the native population in morphology and physiology. Our results show that incorporating physiological data in SDMs does provide different predictions on future distribution ranges with a much higher invasion potential than previously estimated. Furthermore, our results show rapid (less than 30 years) changes in morphology and physiology in different populations suggesting local adaptation. These results stress the importance of using biologically informed data to inform conservation practices.

Frogs Guttural Toads meetings

Max and James get set up in Durban

08 December 2019

John M

Max and James get set-up in Durban

A couple of weeks back, Max and James set off from Stellenbosch in James' Landy with 20 tubs to go to Durban. They almost made it, but the Landy gave out just before Durban and they had to get recovered Landy on one truck and tubs on another. And so all good adventures start!

The reason for the trip was to set up a common garden experiment in Durban with Guttural Toads (Sclerophrys gutturalis) from their native and invasive ranges. The idea is to breed all toads to produce tadpoles, and then rear up the tadpoles in our mesocosms (regular readers will be familiar with these from past blogs: see here). Max will monitor their growth rate, morphology and behaviour of the different groups.

Growing algae for tadpoles: Pint of Science

The set up in a green house in Durban includes cameras for watching tadpole behaviour, blue bins for rearing tadpoles (under benches) and a 'pint of science' growing algae to kick start the mesocosms.

Once everything is set up, all you need is toads. Here you see Max and James scoping out urban and rural areas of Durban to see whether there are appropriate numbers of toads.

Durban urban toad hunt