Dissertation defence (Biology): MSc Nina Cossin-Sevrin

MSc Nina Cossin-Sevrin defends the dissertation in Biology titled “How can cellular-level energy production explain how wild birds cope with environmental stress?” at the University of Turku on 14 June 2024 at 12.00 (University of Turku, Main building, Tauno Nurmela lecture hall, Turku).

The audience can participate in the defence by remote access: https://utu.zoom.us/j/67046108305

Opponent: Professor Jan-Åke Nilsson (Lund University, Sweden)
Custos: Professor Katja Anttila (University of Turku)

Doctoral Dissertation at UTUPub: https://www.utupub.fi/handle/10024/177363


Tiivistelmä väitöstutkimuksesta:

Nothing happens in Nature without energy. Within cells, mitochondria produce that energy by oxidizing nutrients: but how efficiently they do that varies between individuals, and this variation can have far ranging effects, modulating growth, reproduction and survival.

During my PhD, I investigated how metabolic efficiency could be used as an indicator of quality in wild birds. I focused on particularly stressful episodes in their life: growth, and reproduction. In order to obtain more generalisable results, I studied two extremely different bird species: a tiny, fast-paced forest passerine, the Palearctic Great tit, and a large, slow-paced seabird: the Subantarctic King penguin.

One of the key results of my work is to show that early life stress, defined either hormonally as an increase in stress hormone, or more generally as adversity in life conditions, can indeed impact mitochondrial metabolism. Experimentally elevated stress hormones, a high mortality risk, or a mismatched birth date (being born under unfavourable conditions) all have the capacity to modulate energy production in the mitochondria. When focusing on the parents, I also found that maintaining energy production through the stress of breeding requires specific strategies, and that males and females can find different ways of achieving that.

This work also allowed me to explore both the use and the limits of in-vitro high-resolution respirometry methods for studying wildlife. Methodologically, I focused on the metabolically active red blood cells, which provide a low-invasive way of studying wild birds. However, this work was also an opportunity to reflect on the difficulty of defining even central concepts as mitochondrial efficiency and, in the end, metabolism itself, within the framework of ecology – especially when faced with such remarkable physiological feats as surviving a freezing Finnish winter for a 20-gram passerine, or endlessly swimming through the great southern ocean for a King penguin.
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