Thermal adaptation in a model pest insect

Lewis, Rebecca (2020) Thermal adaptation in a model pest insect. Doctoral thesis, University of East Anglia.

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Climate change is one of the key issues of our time, causing rapid changes to habitats worldwide and exerting novel pressures on natural populations. Central to understanding species responses to climate change is the process of thermal adaptation, whereby populations adapt to increased or changing temperatures. However, we do not understand how important thermal adaptation is in nature, nor the phenotypes that underpin it. Understanding thermal adaptation in insect species is of particular interest, as they provide many ecosystem services (e.g. pollination, pest control and recycling of organic matter), and are particularly vulnerable to temperature changes due to their inability to thermoregulate. Additionally, several pervasive pest species are insects, so understanding how they will respond to climate change will have major impacts on food security. Here, I investigate thermal adaptation using Tribolium castaneum, which is the model beetle and a globally important pest of stored products. I use experimentally evolved populations exposed to control temperature (30°C) or stressful high temperature (38°C) for over 50 generations, to investigate how thermal adaptation occurs and the effects of population demographics and life history on this. I found that high temperature lines had lower overall reproductive output compared to control lines, even when reproduction occurred at high temperatures. I then experimentally increased population size and induced migration into the high temperature lines for 10 generations, to increase levels of genetic diversity, but found that this did not result in increased reproductive output or survival. However, when the experimental populations underwent development at high temperature, I found markedly reduced reproductive output in the control lines, but not the high temperature lines. Development at high temperature affected the fecundity of adult females and the fertility of adult males, and I identified morphological differences in the ovaries and testes of beetles following development at 38°C or 30°C. Furthermore, this adaptation appears to occur rapidly, with observable signals of change in reproductive morphology and increased reproductive output within just five generations. This thesis highlights that there is potential for rapid adaptation in insects, which suggests that there is a chance they may cope with climate change. However, it also demonstrated the complexity of thermal adaptation, and more in-depth understanding is required to accurately predict the outcomes of changes in temperature.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 21 Apr 2021 10:11
Last Modified: 21 Apr 2021 10:11


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