Biology subjects

Yek, S. H.

Publications and source records attributed to Yek, S. H..

3 recordsLinked to original sources

bioRxiv2025

Integrative taxonomy and distribution of Apis species in Malaysia

Southeast Asia is the centre of diversification for honey bees (genus Apis). Hence, accurate identification of honey bees found here is instrumental in paving the way for studying evolutionary relationships, biogeographic patterns, and management of these key pollinators. In this study, we characterized Apis species diversity across peninsular Malaysia and Borneo Malaysia using an integrative approach combining morphological traits and mitochondrial markers (CO1 and 16S rRNA). Field collections included both managed and wild colonies of A. mellifera, A. cerana, A. dorsata, A. florea, and A. andreniformis from peninsular Malaysia, as well as two additional cavity-nesting species of Borneo A. koschevnikovi and A. nuluensis. Species identification was performed based on morphological features, nesting ecology, and subsequently validated through sequencing. Samples collected from peninsular Malaysia showed congruence between field/morphological and molecular identification. In contrast, cavity-nesting bees from Borneo exhibited overlapping morphological characteristics leading to misidentification of species. These findings suggest the reliability of carrying out field-based identification of honey bees in peninsular Malaysia but requires molecular validation for Borneo region. The limitations of morphology-based interpretation for Borneo cavity-nesting bees highlights the need for more population-level and speciation studies on these species.

ecology↗

bioRxiv2025

Tracking the zombie ant graveyards' dynamics at Mulu National Park, Borneo, Malaysia

Ophiocordyceps unilateralis sensu lato is a parasitoid fungus that predominantly infects ants from the Camponotini tribe, inducing behavioural changes to enhance its survival and reproduction. The most notable change occurs during the final infection phase, where the infected ant leaves its nest to perform the death grip, hanging upside down and biting onto a substrate to anchor itself. In the tropics, these infected ants congregate at specific locations known as zombie graveyards, which have optimal conditions for spore dispersal. This study examines the spatial dynamics of known graveyards at a national park in Borneo, Malaysia, by assessing existing sites and identifying new ones. We located old graveyards at Night Walk and Paku Trail and discovered a new one at Botany Loop. The density of ant cadavers per quadrat increased slightly, from 1-3 ants/m2 to 2-4 ants/m2. While the graveyard size at Night Walk remained similar, Paku Trail experienced a nearly two-fold reduction, decreasing from 197 m2 to 97 m2. At Night Walk, three ant hosts were identified, with Colobopsis leonardi being the dominant ant host across all graveyards. Without genetic tests, we could not confirm whether the same O. unilateralis infects all ants in the graveyards. Our findings suggest a general site fidelity of zombie graveyards, with hotspot densities varying spatially, potentially influenced by microclimatic changes. Long-term monitoring of graveyard dynamics is essential for understanding natural infections and the effects of environmental conditions on parasitoid-host ecology.

ecology↗

bioRxiv2024

Symbiont loss and gain, rather than co-diversification shapes honeybee gut microbiota diversity and function

Studying gut microbiota evolution across animals is crucial for understanding symbiotic interactions but is hampered by the lack of high-resolution genomic data. Honeybees, with their specialized gut microbiota and well-known ecology, offer an ideal system to study this evolution. Using shotgun metagenomics on 200 worker bees from five honeybee species, we recover thousands of metagenome-assembled genomes and identify several novel bacterial species. While microbial communities were mostly host-specific, we found both specialists and generalists, even among closely related bacterial species, with notable variation between honeybee hosts. Some bacterial generalists emerged host-specific only at the strain level, suggesting recent host switches. While we found some signal of co-diversification between hosts and symbionts, this was not more than expected by chance and was much less pronounced than what has been observed for gut bacteria of hominids and small mammals. Instead, symbiont gains, losses, and replacements emerged as the predominant process for honeybees. This highly dynamic evolution of the specialized honey bee gut microbiota has led to taxonomic and functional differences across hosts, such as the ability to degrade pollen-derived pectin. Our results provide new insights into the evolutionary processes govern gut microbiota diversity across closely related hosts and uncover the functional potential of the previously underexplored gut microbiota of these important pollinators.

microbiology↗