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James & Natasha present in Canada

12 September 2020

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

INVASIVE CLAWED FROG, XENOPUS LAEVIS, CAN IDENTIFY LOCAL PREDATORS REGARDLESS OF COEXISTENCE TIME

Natasha Kruger, Anthony Herrel, Jean Secondi, and John Measey

Invasive species are exposed to novel predators after their establishment in a novel environment. Defences against novel predators may not be efficient at least at an initial stage. The presence of an anti-predator defence is an important parameter that may determine the ability of local communities to control the expansion of invasive populations. The African clawed frog, Xenopus laevis, is a globally invasive amphibian. In western France it faces predators functionally similar to predators found in its native range (South Africa), however, its invasive range has expanded to overlap the range of an invasive crayfish predator. We tested whether naïve X. laevis tadpoles from the invasive French population exhibit anti-predator response to local predators, and whether the response depends on the degree of relatedness with predators encountered in the native range of the frog. Alternatively, if naïve tadpoles may express generic neophobia to any cue they are not familiar with. We exposed naïve lab-reared tadpoles to a non-predator water snail, Planorbarius corneus, a native beetle, Dytiscus dimidiatus, and an invasive crayfish, Procambarus clarkii. Species of the Dytiscus genera are present across southern Africa while no related species to crayfish occur in X. laevis’ native range. We found that X. laevis tadpoles innately reduce their activity when exposed to D. dimidiatus and P. clarkii stimulus cues. The innate response to P. clarkii indicates that X. laevis tadpoles are not naïve to the invasive crayfish. Thus, limiting the effects of these predators on the control of X. laevis, however, previous studies have found that P. clarkii mitigate the effects of other invaders. The complex interactions between co-invaders are essential to explore.

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

SHRINKING BEFORE OUR ISLES: THE RAPID EXPRESSION OF INSULAR DWARISM IN THE INVASIVE POPULATIONS OF GUTTURAL TOAD (Sclerophrys gutturalis) IN MAURITIUS AND RÉUNION

James Baxter-Gilbert, Julia L. Riley, Carla Wagener, Nitya. P. Mohanty, and John Measey

Island ecosystems have traditionally been hailed as natural laboratories for examining phenotypic change, including dramatic shifts in body size (e.g., island gigantism or insular dwarfism). Similarly, biological invasions can drive rapid localised adaptations within modern timeframes. Here we compare the morphology of two invasive guttural toad (Sclerophrys gutturalis) populations in Mauritius (est. 1922) and Réunion (est. 1927) to their genetic source population from Durban, South Africa. We found that female toads on both islands were significantly smaller than mainland counterparts (reduction in body size by 33.9% and 25.9%, respectively), as were males in Mauritius (22.4%). We also discovered a significant reduction in the relative hindlimb length of both sexes, on both islands, compared to mainland toads (ranging from 3.4 - 9.0%). Our findings suggest that the dramatic reshaping of an invasive amphibians’ morphology, leading to insular dwarfism, can result in less than 100 years.

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...


A talk on Cane Toads by Georgia Ward-Fear

30 August 2020

A talk on Cane Toads - by Georgia Ward-Fear

At the end of 2019, Georgia and I began writing a chapter together on ethics in amphibian invasions. This turned out to be quite an undertaking, and it was a great privaledge to work with Georgia on this now accepted manuscript (see here for link to come...). I mentioned to Georgia that I was giving a class on Invasion Biology to our 3rd year undergraduates at Stellenbosch University, and she immediately volunteered to give them a talk all about Cane Toads. She recorded this ahead of time, and so I share it with you below:

Cane Toads have become a specially important group to the MeaseyLab since we started studying Guttural Toads some five years ago. The two species both belong to the family Bufonidae, but are not otherwise closely related. However, both being large bufonids we became interested in whether the same adaptations that have been extensively researched in Cane Toads could also be found in Guttural Toads. Indeed, so much work has now been done on Cane Toads, that we can use this as inspiration for questions for a long time to come.

Thanks so much to Georgia for stepping forward and volunteering to present for the BDE345 students - I'm sure that they really appreciated it. You're a star!


Changing their behaviour

15 June 2020

Behaviour change and a hormonal link

Who could forget the fantastic visit or Carla Madelaire and Adriana Barsotti to the MeaseyLab back in January 2019 (see here)? The two spent only a few months in the lab, but worked super hard on a few experiments that drilled down into the relationship between hormones and behaviour of guttural toads when they are dehydrated.

Today sees the beginnings of all the fruit of their labors with the publishing of Carla's behavioural paper in Behavioral Ecology and Sociobiology!

This paper represents a significant step forwards as we show that after only 20 years of invasion into the dry conditions of Cape Town, Guttural Toads have changed the way that they think about water. When you find it, you stick with it! In this paper, Carla shows a link between this water finding behaviour and the hormone corticosterone. Adriana has another manuscript (submitted) that further investigates this phenomenon also with Guttural Toads. 

It was a great pleasure working with both of you and we look forward to more work and celebrations in the future (there will be cake & cachaça!). Last January, we celebrated their arrival (see here).

The intrepid duo catching toads in Durban with the all important yoghurt pot!

To read more about Carla and Adriana and their adventures in South Africa, see blog posts here, here, and back in Brazil here.

Madelaire, C.B., Barsotti, A.M.G., Wagener, C., Sugano, Y., Baxter-Gilbert, J., Gomes, F.R., Measey, J. (in press) Challenges of dehydration result in a behavioral shift in invasive toads. Behavioral Ecology and Sociobiology    https://doi.org/10.1007/s00265-020-02866-5 pdf


Publicity for Biological Invasions in South Africa

05 June 2020

Publicity for our new book: Biological Invasions in South Africa

Today is Environment Day, and to celebrate, Brian van Wilgen has been given interviews to journalists about our new book: Biological Invasions in South Africa. Since the book was released free online in March (see blogpost here), the chapters have been downloaded 154 thousand times! 

Some of the great information shared in this book is about alien trees that consume ~5% of our scarce water resources, in South Africa. Invasive species pose a direct threat to the survival of almost half of 1 600 native species listed in South Africa’s Red Data List. The book provides information on 1 422 alien species including plants, birds, mammals, fish, reptiles & amphibians. 

A newpaper article in the Witness:

You can listen to Brian's interview on this podcast or this radio interview.


A very memorable and toady Cape Herp Club

08 April 2020

The Toad Team pull off a spectacular presentation for Cape Herp Club

In these times of uncertainty, there are opportunities to do things differently. Normally, the Cape Herp Club meets every other month in the lab of one of the host groups. This month, we couldn't meet as we are all confined to our homes to comply with the government emergency legislation to fight COVID-19.

As it was the MeaseyLab's turn to host the Cape Herp Club, we decided to have a whole bunch of talks about Guttural Toads, Sclerophrys gutturalis, and the work that the lab is currently engaged in. Because we weren't allowed to meet in person, we decided to do a video conference, and that allowed us more opportunities to get creative about the talks we could give.

Many blog readers will remember the visit of Carla & Adriana last year from Brazil (see blog entries here, here and here). You will also remember that last month, Max had to go back to Germany before finishing his experiment (see blog post here). We were able to invite them them all to participate in our presentation.

Interrogating an invasion: details on differences between native and invasive populations of Guttural Toads

Giovanni Vimercati (couldn't make it but sent a presentation from Switzerland)* - Insights from more invasions

James Baxter-Gilbert (in Stellenbosch) - Morphology and performance of native and invasive populations

Max Mühlenhaupt (in Berlin) - Breaching the gap: From egg to toad

Carla Madelaire (in Arizona) - Water seeking behaviour of native and invasive toads

Adriana Barsotti (couldn't make it but sent a presentation from Cyprus)* - Challenges of a novel range

Carla Wagener (in Bellville) - Shit don't lie

Sam Peta (in Stellenbosch) - Proposed work on dietary niche and trophic interactions

Natasha Kruger (in Mosel Bay) - Parasites of native and invasive populations

It was amazing to see more than 30 people join this Cape Herp Club meeting.

But because we didn't have to have people physically present, we could invite our collaborators from all over the world. 

In attendance were Guttural Toad collaborators:

Claudia Baider & Vincent Florens (Mauritius)

Morne du Plessis (Pretoria)

Fernando Ribiero Gomes (Sao Paulo)

Louis du Preez (Potchefstroom)

Of course, most people were alone in their houses, but a few were able to show us how (and how not) to do social distancing.

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