Unravelling the historical impacts of sea-level change on primary rainforest tree species

• Main Author: Ow-Yeong, Yook Kit
• Other Authors: Jarkko Tapani Salojarvi
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Science::Biological sciences
• Online Access: https://hdl.handle.net/10356/166603
• Institution: Nanyang Technological University

Environmental changes, including sea level, can have profound impacts on different plant species, several of which are not well understood. Kempas (Koompassia malaccensis) is a long-lived, tropical primary rainforest tree found in the Sundaland biodiversity hotspot. It was previously discovered to be genetically diverse despite its dwindling population. Our study aims to investigate the effects of bioclimatic and sea level fluctuations on the effective population size of Koompassia malaccensis (K. malaccensis) over the past 20 thousand to 5.4 million years through ecological niche modelling using 19 bioclimatic variables and demographic inference using SMC++. We have three main findings. Firstly, large parts of the now-submerged Sunda Shelf were likely once suitable for K. malaccensis occurrence. Additionally, K. malaccensis experienced a few cycles of reductions and recovery in effective population size throughout the Pleistocene and Pliocene epochs. Finally, we found that ecological niche models built using only bioclimatic variables and sea level explain changes in effective population size to a limited extent. More meaningful variables are needed to better explain historical demographic changes. Our findings support conservation efforts of primary rainforests and inform the future creation of more comprehensive models to study the effects of climate change on tropical plant species.