A joint meeting of the Herpetological Association of Africa and the African Amphibian Working Group in Wilderness, South Africa: 26 – 29 November 2024

Each of these groups usually meets every two years separately, so it was for the first time in their existance that they met in back-to-back meetings in Wilderness South Africa. First up was the 20th meeting of the AAWG, with plenty of familiar faces from across the globe. 

Next was the 16th meeting of the HAA, which also had great representation and considerably more delegates. 

   

The meeting featured presenters from 9 different African countries: Madagascar, Nigeria, Tanzania, Uganda, Ethiopia, Kenya, Ghana, Namibia and South Africa. This was certainly the best representation of the continent since each of the meetings started. 

The following talks featured MeaseyLab members:

Home and away: the gut microbiome of Xenopus laevis in native and invasive populations

John Measey; Jiankun Yu; Dareen Almojil; Stephane Boissinot; Laurie Araspin; Carla Wagener; Greg Pauly; Reed Ojala-Barbour; Claudio Soto-Azat

The vertebrate gut microbiome is a community largely composed of bacterial, fungal and viral components, whose molecular component equal that of the host. The influence of the microbiome is known to be significant both on an individual basis, and also on population scales in a wide range of host organisms. The gut microbiome is known to be involved with key attributes of animal health, including assimilation of nutrients, immuno-defensive functions and host behaviour. In this study, we used bacterial 16S rRNA amplicon-based sequencing for metataxonomic classification of the gut microbiome of individuals from 12 native populations of Xenopus laevis. These populations were selected to represent the native range of the host species. From the 16S rRNA community profiles, we determine the components of the core microbiome of X. laevis and ask whether deviations from the core are associated with the environmental context in which they live. In addition, we sampled populations from Chile (4) and USA (7) to determine what aspects of the core microbiome are retained by non-native populations. This represents the first time that the microbiome of X. laevis has been assessed across such diverse conditions and provides data that will help understand the role played by the environment within this model organism.

Southern Africa Amphibian Red List Project – updated assessments for the region lead the GAA3

Jeanne Tarrant; Joshua Weeber; Oliver Angus; Adrian J. Armstrong; Ninda L. Baptista; Francois S. Becker; Rebecca M. Brunner; Werner Conradie; Louis H. du Preez; James Harvey; Adriaan Jordaan; Keir Lynch; John Measey; Mohlamatsane Mokhatla; Darren W. Pietersen; Fortunate M. Phaka; Jennifer Swanby; Krystal A. Tolley; Andrew A. Turner; Luke Verburgt

As the most threatened vertebrate class on earth, amphibians are leading the biodiversity extinction crisis. The 2nd Global Amphibian Assessment (GAA2) found that 41.5% of species globally are at risk of extinction, these extraordinary and diverse creatures are experiencing the worst population declines and highest extinction risk of any vertebrate group. South Africa has a good history of updating Red List assessments and has done so consistently since 2004 with the publication of the Atlas and Red Data Book. As some of the first assessments to contribute to GAA3, regional updates are in process for 246 southern African amphibian species. A very high proportion (approximately 74%) are endemic to the region, emphasizing the need to understand their conservation status, and prioritize conservation resources. Over 150,000 records were collated from 16 institutions (including citizen science platforms) and numerous private collections. A team of twenty experts contributed to assessment updates, with the support of the IUCN Amphibian Red List Authority, Amphibian Arc, SANBI and Re:Wild. Applying the IUCN Red List criteria according to IUCN guidelines, the current assessments have resulted in category changes for over 40% of priority species, including assigning a status to all but one Data Deficient species and all Not Evaluated species. Future climate scenarios (2050s) were modelled for South Africa’s threatened frog species and predict a wide range of distributional impacts, which will be exacerbated by ongoing land-use change. 35% of threatened species are likely to be highly impacted by future climate change scenarios. The updated assessments will be published by IUCN in the first half of 2025, and the outcomes of this work will be invaluable in informing an updated conservation and research strategy, the National Biodiversity Assessment, and has already contributed to identifying species in need of urgent recovery in the next decade.

The BioSoundSCape project: Automating frog detection for ecological monitoring in the Cape Floristic Region

Andrew A. Turner; John Measey; Oliver Angus; Colleen Seymour; Alan Lee; Rose Snyder; Festus Adebgola; Leo Salas; Matt Clarke

Monitoring frogs has the potential to provide useful insights into measuring ecosystem health and the management of these ecosystems. Yet currently this monitoring is highly restricted, in space and time consuming. Data acquired from automated sound recording devices can extend the reach of ecological monitoring. The BioSCape project is a large, multi-party collaboration with NASA that aims to relate biodiversity patterns on the ground with remotely sensed, cutting edge spectral imaging that provides very high spectral resolution across the electromagnetic spectrum. One of the novel ways to measure biodiversity is to measure bioacoustic diversity. The BioSoundSCape project deployed a large number of automated sound recorders (AudioMoths) across the Cape Floristic Region and recorded nearly 1 million sound recordings. These recordings are freely available on NASA’s Distributed Active Archive Center. The project set up pattern matching algorithms to detect frog calls of 13 frog species, ran statistical pattern matching, validated results and used the resultant validated sound sonographic signatures for training input to a machine learning (computational neural network) system as implemented by RFCx in Arbimon. From this we calculated diversity indices and present examples of these outputs. Once the entire data collection, processing and analysis can be automated, it can realise the ability for large-scale, frog and ecosystem monitoring.

A talk for the University of Portsmouth

Readers of the blog will be familiar with my repeated visits to the University of Portsmouth and in particular the European Xenopus Resource Centre (EXRC). In January 2024 (see here) I became a Visiting Researcher, School of Biological Sciences, University of Portsmouth, and so during a brief visit to Portsmouth this week, I was asked to give a talk to the School.

The EXRC is a special place for anyone working on Xenopus as they hold breeding stock for anyone in Europe working on Xenopus frogs. Recently, we were able to supply them with some gametes from the progeny of wild caught animals from South Africa. I hope to report more on that project here on the blog in future.

Matt Guille leads the EXRC and received a flashing Xenopus neon sign for the EXRC lab.

Measey, J. (2024) What can biological invasions teach us about rapid evolutionary change? 1 November 2024 School of Biological Sciences at University of Portsmouth

Laurie presents at the 22nd European Congress of Herpetology

The 22nd European Congress of Herpetology took place in Wolverhampton UK and Laurie Araspin presented her PhD work on Xenopus acclimation:

Locomotion and physiology depending on temperature in Xenopus laevis native and invasive populations
Araspin, L., Measey, J. & Herrel, A.

Ectothermic species are dependent on temperature, which drives many aspects of their
physiology. The distribution of native and invasive populations of the frog Xenopus laevis is
characterised by an exceptional latitudinal and altitudinal range. Along these gradients, the
thermal environment changes and populations experience different temperatures. We assessed
phenotypes depending on the temperature of individuals coming from six native and one invasive
populations. We measured the thermal dependence of locomotor performance in adults given its
relevance to dispersal, predator escape, and prey capture. Results show that the thermal
performance optimum differs among populations, and the minimum critical temperature varies
among populations coming from different altitudes. Then, we compared the standard metabolic
rate (energetic cost of organismal maintenance; SMR) depending on temperature, as locomotor
performance strongly relies on metabolic activity. We tested SMR in populations from the native
range, inhabiting low (South Africa) and high altitudes (Lesotho), and from the invasive range
(France). Regarding the contrasting climatic environments of the studied populations, differences
in the SMR depending on temperature are expected. We found that populations exhibit different
energetic costs in metabolic activity and that populations show reduced metabolic activity in the
temperature range the most encountered in their environment (i.e., in cold temperatures for
populations from colder environments and in hot temperatures for populations from warmer
environments). The ability of this species to change its optimal temperature for locomotor
performance and its metabolic activity across extremely different climatic environments may help
explain its invasive potential. These findings highlight the extraordinary thermal adaptation ability
of the species. This ability to cope with a wide range of variation in environmental temperatures
suggests that the species may be particularly good at invading novel climatic areas.

The 10th World Congress of Herpetology in Kuching, Sarawak, Malaysia

It was a great pleasure to attend the 10th World Congress of Herpetology in Kuching this month. The congress was a great opportunity to catch up with herpetologists from across the planet, including many that I have known for many years as well as many many new faces. 

I presented my work on the gut microbiome of Xenopus laevis, and was pleased to see many former members of the MeaseyLab presenting their own work. This included Max who presented work he conducted during his MSc on Scerophrys gutturalis. 

The peculiar tale of Xenopus laevis in Hamamatsu City, Shizuoka Prefecture

There are a few pathways for invasive populations of African clawed frogs, Xenopus laevis. The first, and oldest, has been the accidental (or deliberate) release of animals associated with laboratories using animals for pregnancy testing or as lab models. More recently, the number of invasions due to released pets has been on the rise, and we have seen examples of this in the USA, Belgium and China. Most of the invasions in Japan also appear to be related to pets, but not the population in Hamamatsu City.

In addition to being the laboratory model amphibian, the tadpoles of Xenopus are also used in a method known as FETAX (Frog Embryo Teratogenesis Assay – Xenopus) where they are used to measure toxicity of the water. I presume that it was this reason that led the City of Hamamatsu to release Xenopus tadpoles into one of their polluted Lake Sanaru in 1982 (see Arao & Kitano 2006). This means that the population found by Arao & Kitano in 2005 in an aquaculture area raising eels was over 20 years old at that time, but is now over 40 years old.

I was reliably informed that the animals were still there 5 years ago, and so I teamed up with Dr. Hisanori Okamiya from the Museum of Natural and Environmental History in Shizuoka. After spending a frutless morning searching in Makinohara (which apparently also had a population 5 years ago), Hisanori and I started looking around the eel farms.

A farmer at the first farm that we asked at pointed to a dead floating frog floating in a newly sterilised eel tank and asked us if this was the type of frog we were looking for. I fished it out with a very long net, and could immediately see that it was indeed a (very) dead Xenopus laevis. 

The farmer confirmed that he gets these frogs in his eel tanks all the time, but that the population appeared to be getting smaller over the last 5-10 years. We placed out traps in a large outdoor pond, the presumed source of frogs, and came back the next day very disappointed to find that there were no animals at all inside. 

I suggested that we keep on asking at eel farms and see whether anyone else was finding animals, or perhaps could point to their source. As we headed down the row of farms along the road next to the bullet train track, sightings appeared to be getting less and less. We decided to take a break and have some lunch. It had been pouring with rain all night and all morning, and Hinasori and I had been getting very wet despite waterproofs. It seemed fitting that we have eel for lunch, and so I splashed out. 

After lunch, we headed back the way we came. We stopped in the neighbouring aquaculture farm (not an eel farm, but a farm for koi carp). We couldn't find anyone around. We searched around all of the buildings, but couldn't find anyone. As we were walking through a big puddle at the side of an eel pond, Hisanori saw a frog swimming in the water. Happily, I filmed what happened next, so you'd best watch the video below:

We managed to find the owners of the farm who allowed us to fish around in one of their empty fish ponds, where we found lots of tadpoles and lots more metamorphs, but no adults. 

So it seems that 42 years after releasing tadpoles into Lake Sanaru, African clawed frogs are still alive and well in Hamamatsu City.

Further Reading:

Arao, K. and Kitano, T., 2006. Xenopus laevis from Hamamatsu City, Shizuoka Prefecture, Japan. 爬虫両棲類学会報, 2006(1), pp.17-19.