Dr. Sze Huei Yek

My research interest is broadly in the evolutionary ecology and behaviour. Specifically I am interested in the mechanisms that underlie the social chromosome associated with variation in queen number in the Alpine silver ant Formica selysi. I study the origin and maintenance of this polymorphism by combining genomic/transcriptomic and behavioural ecological experimentation.

The study system is an invasive woodwasp-fungus symbiosis and its nematode parasite as biological control agent. The study system is native in Europe and Asia and had become an important pest in the pine plantations throughout the Southern Hemisphere. I presented the ideas of using biological control agents to study evolutionary processes in invasive populations, with the arguments that biological control agents (parasites) have many attributes, such as known phenotype and genotype source and controlled population size, for experimentations that invasive species lack. As a test to our argument, I’d completed
(a) a transcriptomic project looking at the expression profiles of biological control agent on the invasive host populations, the results serving as a reference for comparisons between populations’ susceptibility to the biological control agent,
(b) a comparative genomic project exploring the transition of an alternative spliced immune genes from solitary to eusocial lifestyle in hymenoptera, and
(c) invertebrate community diversity and turnover between native and invasive plantations.

I used leaf-cutting ants as model system in my PhD and woodwasp-fungus-nematode study system in my postdoctoral research. The main questions in my PhD is to untangle the defense complexities of leaf-cutting ants’ symbiosis. I used transcriptomic approach, resulting in the first genome-wide study on immunity expressions in ants, and also a pioneering study with regards to genome wide gene expression responses in any gene ontology group. I also combine microbiology pathogen assays and behavioural experiments to draw clear conclusions regarding trade-offs of immune system and prophylactic behavioural defense mechanisms. In this respect, this is considered a landmark study in the field of ant immunity evolution. Furthermore, I used different pathogens (from saprophytes, generalist to specialist parasites) on the ants and/or symbiotic fungus to clearly demonstrate the ability of a defensive exocrine gland to regulate its’ secretions based on the ‘risk’ level. These results are discussed in the broad context of the exocrine glands having the elements of immune system, hence functioning as a ‘cuticular immune system’ of leaf-cutting ants. I perform cross-fostering experiments to determine co-evolutionary processes of adaptations between the defensive bacteria and their leaf-cutting ant hosts. From these work, I was invited to write a review on the current knowledge on ant-fungus-parasite evolution. In this review, we discussed the application of Nikolas Tinbergen’s scheme of proximate and ultimate questions on this study system and outlined impending questions for future work.

Other than these main methodologies and evolutionary approaches deriving from PhD and postdoctoral projects, I have also passion and experience involving field-lab-based studies of tropical ants, Australian ants, and invertebrates associated with ants’ symbiosis. Previous research topics includes the following: behavioural evolution of batesian mimicry; conservation planning based on phylogenetic diversity; and developmental evolution of defensive exocrine gland, all using ants as model system.