James McCoy

Abstract

Phenomics, the high-throughput acquisition of phenotypic data at the scale of the whole organism, has led to considerable advancements in plant biology and medicine, yet applications within animal environmental physiology and evolutionary biology are rare. The main aim of this thesis is to understand what phenomics can contribute to our understanding of Comparative Developmental Physiology (CDP), in terms of how environmental and evolutionary change affects the development of physiological function in aquatic embryos. Additionally, I aim to understand the consequences of changes in high-dimensional phenotyping methods used throughout the thesis within the context of embryonic life history. To achieve this, I characterised evolutionary and temperature induced changes in high-dimensional phenotypic space in embryos of three species of freshwater snail with pre-established sequence heterochronies, evolutionary differences in the relative timings of developmental events. This was achieved through the use of a novel video based approach to phenomics in developing embryos termed ‘Energy Proxy Traits’ (EPTs) that integrate aspects of embryonic physiology and behaviour as a spectrum of energy. I found that evolutionary and intraspecific differences in developmental event timings were associated with high-dimensional phenotypic change, which may themselves act as objects of selection (Chapter 2). Additionally, EPTs revealed interspecific differences in whole-embryo sensitivities to chronic elevated temperature regimes, and considerable differences in responses between different physiological windows of development. EPTs were transferable between species that vary greatly in their developmental itineraries, and physiological windows of development that vary in their observable phenotypes (Chapter 3). Finally, I quantified changes in EPTs alongside life history traits, following serial experimental manipulation of nutrient content of developing embryos, with the aim of understanding how induced changes in EPTs affect other aspects of embryonic development (Chapter 4). Increases in total energy and concomitant reductions in size and rates of growth following removal of nutrient content suggest a trade-off between these variables, and a potential re-allocation of energetic reserves following removal of nutrient content in these embryos. In summary, EPTs enabled the continuous acquisition of physiological time series’, revealing evolutionary and environmentally induced changes in high-dimensional phenotypic space, changes which may have consequences for aspects of embryonic life history.

Keywords

Comparative Developmental Physiology, Phenomics, Developmental Biology, Environmental Physiology, Ecophysiology, Evolutionary Biology

Document Type

Thesis

Publication Date

2023

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