2022
Hong Kong is a bit late relative to the rest of the world but we are now finally opening back up to travel. In 2022 I was fortunate visit California, North Carolina, Colombia, Switzerland, Thailand, England, and Scotland. I attended three conferences and somehow avoided COVID through all of it (alas, the postgraduates traveling with me were less lucky in this regard).
Back home in Hong Kong, the lab has been busy with research, teaching, and other fun. We’ve also had some turnover in the lab with new postgraduates starting (Eugene and Tracey) and postdocs departing (Felix, Joss, Susie, and Toby). And Dr. Dufour became known as Dr. Dufour! In 2023 we’re anticipating more changes – the turnover reflects exciting opportunities and challenges for incoming and outgoing lab members.
In personal news I was promoted to “full” Professor official starting Jan 1 2023. I’m grateful for and flattered by the recognition – this is clearly a consequence of the outstanding success of the students and postdocs who have come through and are still working in the lab. It’s such an impressive team and I’m thrilled to continue our work with the added responsibility that comes with this change. I’m also eager to contribute in new ways to HKU and Hong Kong. In October of this year I celebrated my tenth year at the University and in the city. It’s been a memorable decade… looking forward to the next ten years. There is a lot of conservation and science to do.
Every year I like to end the year by highlighting the back story and interesting stories from a few of the papers to come out of the lab. This year we had some exciting pieces come out…
Complicated link between resource restriction and thermal tolerance
My lab has been studying the thermal tolerance of butterflies and insects for many years. One caveat to our work has been that nutrition could affect tolerance. This has always been in the back of my mind thanks to my PhD advisor Carol Boggs, who has done a lot of authoritative research in this area. My hunch was that thermal tolerance should be reduced under resource stress.
In stepped Yuet Fung Ling who examined the question of starvation and thermal tolerance for the butterfly Mycalesis mineus as part of his PhD. In 2020 he started a lab colony of the species for the tests… this turned out to be an eventful year. As HKU went through various rounds of shutdowns and our building closed a couple times, Fung persisted and kept good care of the butterflies. He then undertook a complex design of multiple temperature treatments (which produced dry and wet season forms), larval starvation, and adult starvation to see how these treatments affected thermal tolerance. Surprisingly, we found no effect of starvation on thermal tolerance! Sure, the starvation treatments affected other life history traits (indicating that the treatment was effective), but tolerance was unaffected.
The optimist in me sees this result as supporting evidence for the utility of thermal tolerance experiments. That tolerance is robust to starvation suggests that our results from these experiments can be trusted to some extent. On the other hand, the starvation treatments were very specific to the experiment, and of relatively short duration. I suspect that there likely are important resource restriction and thermal tolerance interactions under variable conditions, other than those represented in our experiments. In any case, Fung’s experimental evidence helps to tease apart some of the complex relationships between thermal tolerance, plasticity, and resource availability (for both larvae and adults).
See paper in Comparative Biochemistry and Physiology Part A
Impacts of Tokay gecko trade on source and destination
Pauline Dufour’s PhD thesis started off investigating the thermal biology of nocturnal and diurnal lizards (see her work on the influence of diurnal timing of tolerance measurements on species tolerance estimates published in Conservation Physiology). But early in her PhD she also made it clear she intended to do a study on wildlife trade focused on nocturnal lizards. Having lived in Laos before moving to Hong Kong, she was keenly aware of the important impacts of trade on herpetofauna conservation. She soon began gravitating towards the iconic Tokay gecko (Gekko gecko).
In early 2020 we teamed up with Caroline Dingle and Yik-Hei Sung to draft a proposal to research Hong Kong’s role in the trade of Tokays. Later that year we were fortunate to have the proposal funded by the Ocean Park Conservation Foundation and Pauline was off! Working with an impressive team of undergraduate researchers and research assistants, Pauline sampled wild Tokay populations all across Hong Kong and also went to local markets where dried Tokay gecko specimens were sold for traditional medicine. After collecting all of the samples she went into the lab and analyzed the genetics and stable isotopes of the specimens and compared them to one another. We wanted to know: 1) where were market Tokays coming from? And 2) was there any evidence that wild Tokays in Hong Kong were influenced by the trade?
Pauline found that the Tokays in local Hong Kong markets were coming from all over Asia. By some estimates, annual trade volumes of Tokays number in the millions. Hong Kong is one key destination for this trade and, based on Pauline’s data, appears to source widely across the region. Second, Pauline found evidence that at least two wild populations appear to have been affected by introductions from the pet trade based on genetic sequencing. To me, this work is fascinating in that it illustrates the significant scale of wildlife trade and also shows how this trade not only reduces wild populations from sources… but the trade can also affect destination points if individuals are released to the wild and become introduced (and potentially) invasive species.
See paper in Proceedings of the Royal Society B and coverage in the HKU Bulletin
Hong Kong’s small and threatened Eurasian otter population
Sharne McMillan emailed me in Nov 2015 with an interest in doing a PhD on Hong Kong’s Eurasian otter. She detailed the scope of her proposed PhD project and noted that “I understand that this would not be an easy project”. I replied and said that I didn’t have any funding for this. We met later and I further expressed my scepticism that such a project would be feasible – at the time we knew otters existed in Hong Kong but we didn’t know much more than that. Sharne was persistent however! With Billy Hau as co-supervisor, we applied for and received funding from the Environment and Conservation Fund as well as the Ocean Park Conservation Foundation. Sharne began her PhD in Sept 2016.
I remember a meeting early on in the project when we discussed the plan for finding otter spraints (i.e. otter poop), critical for the estimation of occupancy and DNA analysis that could provide estimates for population size. “What if we don’t find any spraints?” I was certainly worried about the success of the project given the rarity and elusiveness of the animal. However, it didn’t take long for us to have an answer – Sharne found good numbers of spraints early on. Trekking through the wetlands and ponds of Hong Kong finding spraints is never an easy task (and especially difficult in the summer) but we were finding them. Maybe this research wouldn’t be so tough after all!
Finding spraints was one thing. Getting data from those spraints was another thing entirely! We needed fresh spraints to get quality DNA… and even when we had fresh DNA, we were not always able to extract otter DNA from the spraints. We also conducted diet analysis from the spraints we found. This required assembling reference databases full of fish bones and then going through all of the spraints meticulously to identify the prey composition. While Sharne led all of the exhaustive field and lab work, she was assisted by a large team of undergraduates and research assistants. But it took time. We needed roughly two years for the field work and another two years for sample processing and analysis. In the meantime, Hong Kong released its Northern Metropolis Development Strategy in 2021. The Strategy has major implications for Hong Kong’s otters as most of the development is adjacent to key habitats. Suddenly the results of this work had significant urgency.
Sharne found a number of interesting things from her work. Spraints were restricted spatially to the Mai Po wetlands, a critical habitat for the species. From the genetics, we identified a minimum of seven individuals across the two years of sampling (four in 2018 and three in 2019). There are likely more than seven in total in Hong Kong… but probably not a whole lot more than that. The population is small and spatially restricted. From the diet analysis we found a heavy reliance on fish (over 97%), and mostly gray mullet and tilapia. Such data on the population and diet of the species is absolutely critical. As Hong Kong proceeds with the planning for the Northern Metropolis, Eurasian otter must be central to conservation efforts in the planning. Sharne’s work represents an essential first step in this direction.
See paper in Conservation Science and Practice and coverage of the work in SCMP
Concluding thoughts…
Hong Kong and China appear to be opening up to travel in a way that much of the world did a year ago (or longer). For lab activities, this is great news as it will enable us to further our international footprint. We also have a number of exciting papers in the pipeline and new projects getting off the ground. Stay tuned and have a great 2023.
