E&E PhD Exit Seminar: Does inbreeding exacerbate the effects of elevated temperature in guppies (Poecilia reticulata)?

ABSTRACT
Animals rarely face a single challenge in isolation. When populations become smaller and more fragmented, mating between close relatives, also known as inbreeding, can become very common. At the same time, rising temperatures can place additional stress on animals. A long-standing prediction is that environmental stress can amplify the negative effects of inbreeding, so that the greatest fitness costs occur when both stresses act together. But do these combined effects occur consistently across different traits and biological processes?

In my PhD, I used guppies (Poecilia reticulata) to investigate how inbreeding and elevated temperature influence fitness-related traits across multiple levels of biological organisation. Using a large, controlled breeding and temperature experiment involving more than 2,500 individually reared fish, I examined how inbreeding and elevated temperature influence life-history traits, behaviour, reproduction and stress physiology in guppies. I also tested whether the responses to inbreeding and elevated temperature differ between the sexes.

Overall, my findings show that the effects of inbreeding and elevated temperature are highly trait-dependent and were mostly additive, with limited evidence of inbreeding-by-temperature interactions. Some traits responded primarily to inbreeding, others to temperature, and responses often differed between males and females. Many traits were also relatively robust to one or both stressors.

In this talk, I will present how the effects of inbreeding and elevated temperature vary across the guppy life and discuss what these patterns tell us about the fate of small populations in a warming world.

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BIOGRAPHY
I grew up in Bangladesh, where I completed my Bachelor's degree in Fisheries and Marine Resource Technology and my Master's in Fish Genetics and Biotechnology at Khulna University. My main research interest is how organisms respond to stress, and my research in Bangladesh ranged from stress-induced biofuel production in microalgae to behavioural and morphometric studies in fish and crustaceans. I then moved to Germany as a DAAD scholar to complete a second Master's in Aquatic Ecology at the University of Bremen, where I studied the physiological effects of thermal stress in juvenile European seabass and how dietary supplementation can mitigate the stress. During this time, I also worked on oceanographic and ecological data analysis at the Leibniz Centre for Tropical Marine Research (ZMT). I am currently finishing my PhD at the Australian National University, where I examine how inbreeding and elevated temperature jointly shape fitness-related traits in guppies (Poecilia reticulata). Alongside my PhD, I have broadened my experience beyond the lab, working as a field ecologist with Umwelt Environmental and Social Consultants and joining Diversity Arrays Technology, initially through an internship, where I have been building applied genomic and bioinformatic skills. I am drawn to questions that can be approached at several levels at once, from ecology and behaviour through to physiology and molecular genetics, and trying to understand the links between them is what keeps me learning new techniques and moving between fields.