Ecophysiological responses and adaptations to resource seasonality, nutritional symbiosis in the thyasiridae (mollusca: bivalvia) as a case study

Mariño Coronado, Joany Valentina (2021) Ecophysiological responses and adaptations to resource seasonality, nutritional symbiosis in the thyasiridae (mollusca: bivalvia) as a case study. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Animals show a vast diversity of life-history traits and foraging strategies. Some of these traits arise as a plastic response to environmental conditions, while some strategies result from an adaptive evolutionary process. Regardless of their origin, constraints on energy acquisition play a crucial role in the emergence of both traits and strategies because they define the individual energy budget. For example, in many species, resource abundance determines individual energy input. Yet, other species have symbiotic partnerships through which they can increase their energy acquisition. However, the precise mechanisms whereby seasonal energy constraints can affect an individual’s energy budget and translate to higher ecological levels remain unknown. In this thesis, I show the fundamental role of resource availability in driving trait flexibility and how nutritional symbiosis may be an adaptive foraging strategy in response to a seasonal resource abundance. Using a mechanistic description of individual metabolism, I demonstrate that resource availability is sufficient to explain interspecific trait variability. Moreover, peaks of seasonal food can increase individuals’ biomass and reproductive output, hence explaining known ecogeographical rules. Focusing on thyasirid bivalves, I reveal how nutritional symbiosis can alter the host’s energy budget and, consequently, define population dynamics. My results are the first step leading towards understanding the role of symbiosis in population and community dynamics. Broadly, this dissertation contributes to building the theoretical foundation necessary for a mechanistic understanding of how individual metabolism, together with environmental factors, determines species traits and population dynamics. Furthermore, my findings motivate experimental investigations to confirm the theoretical results and test the proposed hypotheses. Due to the current alterations to ecosystems, disentangling the mechanisms underlying life-history traits and foraging strategies is fundamental to understand and predict biodiversity dynamics under climate change.

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