Research

Current Projects

The role of developing individuals in ant societies

Ants develop in complex social environments where they interact with both adult nest members and other developing individuals. However, developing ants are often perceived as powerless and their social role within societies remains poorly understood. In Formica wood ants, larvae actively influence their own survival by engaging in egg cannibalism (Schultner et al. 2013), a prime example of selfish offspring behavior. Whether a larva engages in cannibalism depends on its own sex as well as its genetic relatedness to the egg (Schultner et al. 2014), which suggests that larvae are able to assess variation in their social environment. By adjusting egg consumption behaviour to social environment, larvae may even be able to help defend the nest against social parasites (Pulliainen et al. 2019). These are just some of the cool things developing ants can do (for another example, see Pegnier et al. 2019) and there are many more ways that brood influence social processes in insect colonies (Schultner et al. 2017, Schultner & Pulliainen 2020). By taking a novel approach focused on brood, this project aims to shine new light on social evolution.

Caste determination and differentiation in ants

Individuals that share the same genes can follow different developmental pathways so that as adults, they differ in shape, size and behaviour. Much of this variation is due to phenotypic plasticity, which allows organisms to express a range of phenotypes in response to variation in their environment. However, we still lack basic understanding of how environmental variation is translated into morphological, physiological and behavioral differences. Using the unique genomic model ant Cardiocondyla obscurior, a species with two female and two male castes, this project aims to uncover the environmental factors and molecular mechanisms associated with differential caste development. This project is based on a recent study suggesting that sex differentiation pathways have been co-opted to regulate differential caste development (Klein et al. 2016) and is led by Jan Oettler at the University of Regensburg.

Interactions between ants and their bacterial symbionts

Insects are known to harbour a large diversity of inter- and intracellular microbial partners. For insect hosts, the nature of these associations can range from being beneficial to instances of parasitism. One the one hand, insect hosts can depend on symbionts for the production of nutrients essential to growth and reproduction, and symbionts can play a key role in allowing the host to cope with parasites and pathogens. On the other hand, microbial symbionts can manipulate host reproduction to favour their own transmission, sometimes with detrimental effects for host fitness. The cosmopolitan ant Cardiocondyla obscurior is infected with two main endosymbionts: Candidatus Westeberhardia cardiocondylae (Klein et al. 2015) and Wolbachia sp. (Ün et al. 2020). Cand. Westeberhardia cardiocondylae, with its reduced genome, shows signs of being an obligate symbiont and may provide the ant host with a tyrosine pre-cursor molecule used in cuticle development (Klein et al. 2015). Among samples collected worldwide, all colonies from Brazil are infected with Cand. Westeberhardia cardiocondylae, while some but not all colonies from Japan are infected (Klein et al. 2015). The Brazilian and Japanese populations also carry distinct Wolbachia strains, which differ in their infection titres and ability to manipulate host reproduction by inducing cytoplasmic incompatibility (Ün et al. 2020), as well as in their sensitivity to environmental stress. This project focuses on understanding the functional relationship between the ant host and its symbionts, with particular focus on the effects of environmental stressors such as chemical pollution and extreme temperatures.