Yale-NUS faculty’s research contributes to ASEAN’s regional development

Faculty members at Yale-NUS College are involved in a wide variety of research projects, with many of them contributing to critical developments in the ASEAN (Association of Southeast Asian Nations) region. Two such projects are being conducted by Assistant Professor of Social Sciences (Economics) Yu-Hsiang Lei and Assistant Professor of Science (Environmental Studies) Eunice Tan.

Covering countries such as China, Laos, Thailand and Myanmar, Asst Prof Lei studies how the dams located upstream of the Mekong River affect lower stream water availability and agriculture productivity. He also collaborated with Yale-NUS alumna Momoka Ando (Class of 2021) on this project.

Assistant Professor of Social Sciences (Economics) Yu-Hsiang Lei

On why he chose these countries as his research focus, Asst Prof Lei highlighted the goal of the project, to “examine the economic and ecological impact of dam construction on international rivers where the coordination between upstream and downstream countries is limited.” To investigate this research question, Asst Prof Lei focused on two Chinese dams built along the Mekong River after taking into account their size and strategic location. According to Prof Lei, “the segment of the Mekong River that lies just outside the Chinese border provides a quasi-experimental setup where a major tributary of the Mekong River, Nam Ou River, flows parallel with Mekong mainstream but was not affected by the two Chinese dams during the study period. To causally identify the economic impact of Chinese dams on the downstream countries, we compare croplands close to the Mekong River to those near Nam Ou River before and after the dams were built.”.

Asst Prof Lei then shared with us the hypothesis he had and how the results obtained validated his initial theory. “We hypothesise and confirm that the dams have a positive impact on agricultural productivity, due to their smoothing effect on water discharge. The increase in the water level during the dry season improves irrigation, and, thus, agricultural productivity. On the other hand, the decrease in water level during the wet season has little effect on the agricultural productivity since more than 80% of the annual rainfall already occurs during this period,” he said. Using the extraordinary deficit of rainfall in 2019 as an event study, Asst Prof Lei also found that upstream dams seem to exacerbate water shortages and agricultural productivity downstream during extreme rainfall shortage. “As extreme weather becomes increasingly common due to climate change, there is reason to worry that the dams’ negative consequences could potentially dominate any positive impact it may have on downstream countries. Therefore, the threat of climate change also brings to the forefront the need for more accountability from upstream countries that hold inordinate influence by virtue of geography and the need for better international coordination in the governance of valuable shared resources such as our international rivers,” he said.

Also working on research in the ASEAN region, Asst Prof Tan is studying the ecology, behaviour, and evolutionary adaptations of Southeast Asian phasmids. Live stick insects from Singapore, Malaysia and Brunei were collected before the COVID-19 pandemic outbreak, and are currently being studied in the lab.

Assistant Professor of Science (Environmental Studies) Eunice Tan

When asked about why she chose to study the Southeast Asian phasmids, Asst Prof Tan emphasised the incredible diversity of these species in the region. “There are approximately 3,000 species of stick and leaf insects globally. Stick and leaf insects are especially abundant in tropical regions, and their diversity in Southeast Asia has been documented in recent years. At least 600 species are known to exist in Southeast Asia. However, little is known about the biology and ecology of this group of charismatic insects,” she shared.

This leaf insect is found in Singapore, and it is very difficult to spot because of its remarkable resemblance to leaves. Image Provided by Asst Prof Tan.

Asst Prof Tan also highlighted the distribution of these species in different regions. “For instance, we would see certain species in Singapore and Peninsular Malaysia, because Singapore was not separated so long ago from the peninsular. This is similar for many species of plants and animals. Different species are found in different habitats, so there are highland species that probably did not exist in Singapore as we do not have highlands here,” she said.

Asst Prof Tan on a trip to Brunei in 2019. Image provided by Asst Prof Tan, taken before the COVID-19 pandemic.

Asst Prof Tan’s latest review article, “Motion: enhancing signals and concealing cues”, discusses the intricacies of animal colour patterns and how motion is closely linked to signalling. Inspired by her work on this article, Asst Prof Tan proposed and is the leading editor of the research topic, Signals in motion, which focuses on the impact of movement in the perception of animal signals and cues. She is currently reviewing abstracts for this collection of research to expand the boundaries of knowledge for her general research on animal behaviour and ecological interactions. The study of colour patterns, signalling and motion also furthers understanding of the ecology, behaviour, and evolutionary adaptations of Southeast Asian phasmids. Given the dearth of research on insects in Southeast Asia despite their comparative diversity and abundance, this latest research will enhance the understanding of the ecosystem in the ASEAN region.