Kirstin's paper on duck hybridisation is published

Although many of you are tuned to reading about reptiles and amphibians on this blog, this paper is about one of the large radiation that appeared from within the reptiles many years ago... and they are invasive in large numbers!

Mallard ducks are invasive in many places around the world. They were imported for sport, farming and more recently as pets for large peri-urban gardens. What wasn't well appreciated is that the genus Anas, to which they belong, easily hybridises with the result that the Mallards quickly start forming hybrid populations in many places where they move to. 

The recent rise in many of their populations in urban areas of South Africa caused great concern some years back when a video of Mallard males mating with native Yellow-billed ducks went viral on social media. The matter came up at the CAPE-IAA, a forum of invasive animal workers in the fynbos biome. There was a need for a study as it was clear that hybrids were being produced. And so Kirstin's project was formed to find out exatly what was going on. 

The result that Kirstin found was that in Cape Town there is hybridisation, but that it happens into the Mallard Duck population more than into the native Yellow-billed Ducks. Moreover, the mating seems to be predominantly in the direction of Yellow-billed males mating with Mallard Duck females.

This is not the last word in the story. Colleagues in Kwa-Zulu Natal are sure that Mallard males are the aggressors in that area. It could also be that the situation gets worse over time, with introgression swinging into the native Yellow-billed ducks.

To know more, read Kirstin's paper here:

Stephens, K., Reynolds, C., Measey, J. & le Roux, J.J. (in press) Occurrence and extent of hybridization between the invasive Mallard Duck and native Yellow-billed Duck in South Africa Biological Invasions. https://doi.org/10.1007/s10530-019-02122-6 pdf

BRICS invasion scientists need to keep one step ahead

You've heard about BRICS here before. Brazil, Russia, India, China, and South Africa (aka BRICS) have formed a club mostly as they were kept out of the intial G7 movement (which has now expanded to be more inclusive). They are billed for being between developed and developing nation status, although the reality is that they are both developed and developing. Large sections of the society are rural and developing, whereas the urban areas are mostly developed. 

BRICS countries are a problem as far as invasive species are concerned, as they have the all the problems associated with a developed country (e.g. growing volumes of trade and international partnerships), on top of growing issues associated with developing countries (e.g. rural to urban movements and artisanal enterprises). Add to this that most BRICS countries are biodiversity megahotspots, and you get a growing perfect storm not only of invasions within, but invasive species donated to the rest of the world.

What we really like delving into on this MeaseyLab Blog are not just the problems, but potential ways to solve them. In this popular article for The Conversation, I outline the solution that we recently came up with for our PLoS Biology Perspective piece (that you can find here). 

To read the piece in full, together with the proposed solution, you can click here. Or if you prefer, you can read the original PLoS Biology paper here. 

And, there are old blog posts about the original workshop (here), the PLoS Biology paper (here), and a Press Release from Stellenbosch University (here). You can even read a site in Portuguese here by Ronaldo Silva

Measey, J (2019) BRICS scientists could help stem the tide of invasive species. The Conversation - Africaonline

Publicity for Nitya’s pet-trade paper

Not content with having produced a very popular paper on the pet-trade in amphibians (see blog post here or read the article here), Nitya went on to write a popular article for The Conversation Africa, which has garnered even more attention.

In his Conversation piece, Nitya explains more about the very real dangers that are associated with the pet-trade. Firstly, for animals that are collected from the wild, and for those that are mass bred in captivity. One of the problems that we face is that traders are looking for new species all the time, and this constant search for new ‘products’ is likely to lead to exploitation, and the danger of releasing lots of propagules of a new invasion. He underlines that there is responsibility across the board, from traders to owners.

This story was picked up by eNCA, a TV broadcasting company that covers the African continent. Nitya was interviewed live by Jeremy Maggs, and shared his thoughts on why more attention needs to be paid to the growing trade in exotic pets. You can watch the interview in full on YouTube

Always looking for a story with #MohantyMagic, The Hindu picked up the story and wrote their own piece on the article. They even used a sound bite from Nitya’s co-author!

Interestingly, the Conversation article has been picked up by other news outlets including Infurmation, a site promoting responsibility for pet lovers! Let’s hope that Nitya’s message strikes a chord.

Effects of temperature on the physiology of three African frogs

Some of you will remember Mohlamatsane ‘Mac’ Mokhatla and his work on three species of widespread African frogs: the principally aquatic African clawed frog (Xenopus laevis), stream-breeding common river frog (Amietia delalandii), and the largely terrestrial raucous toad (Sclerophrys capensis). Keen readers will remember that one of Mac’s species changed its name three times during the course of his PhD (see here)! Well, some of that work was immortalised today in a paper summarising the physiology work that Mac did on these three frogs. 

While there’s been quite a lot of work done on the physiology of frogs, most of these studies are done in the northern hemisphere on temperate frogs with similar biologies. Mac chose three very different species: platannas that spend most of their time in water, toads that are mostly terrestrial, and river frogs that spend much of their time jumping from land to water and back. 

The results suggest that vapour pressure deficit (an important trait for frogs that need to remain hydrated) better predicted rates of evaporative water loss than ambient temperature in toads and river frogs. 

Read more about Mac's thesis here or read more the paper here:

Mokhatla M, Measey J, Smit B.2019.The role of ambient temperature and body mass on body temperature, standard metabolic rate and evaporative water loss in southern African anurans of different habitat specialisation.PeerJ7:e7885https://doi.org/10.7717/peerj.7885

Jean Secondi visits from U Angers

Natasha Kruger has spent the past 3 years spending Summer in South Africa, and then spending the next Summer in Angers with Jean Secondi. We’ve featured some of this travelling on the MeaseyLab blog before (see here and here), and also some of the work that Natasha produced (see here). 

Finally, after 3 years of waiting, Jean visited Stellenbosch to familiarise himself with the native habitat ofXenopus laevis(which he knows all too well from years of studies on the invasion in France), to spend some important time working with Natasha, and to attend the African Amphibian Working Group (AAWG) in George. 

We took Jean along on a long weekend to our long term monitoring site for the Cape Platanna in Kleinmond. Sadly, we didn’t find any African clawed frogs in their usual hauntings and all of the Kleinmond sites that normally containedXenopus gilliwere completely dry. We did however, manage to sample a site with Cape platannas in Betty’s Bay. We even found one animal that Andre de Villiers had marked way back in 2014!

It was great having Jean visit the lab, and we really hope that he also enjoyed himself and will take good memories of South Africa back to Angers. We are also really looking forward seeing him again during our visit to Lyon next February to attend Natasha’s defense!