Molecular Mechanisms Underlying Fish Phenotypic Plasticity in the Acclimation to Environmental Stressors

Student thesis: Doctoral Thesis

Abstract

Phenotypic plasticity, the ability of one genotype to produce multiple phenotypes, is crucial to an organism’s capacity to acclimate to changing environments. Acclimation by means of phenotypic plasticity may allow species to cope with fast-changing environments. Phenotypic plasticity can manifest either as acute, developmental, or transgenerational. In this dissertation, I explored the molecular processes underlying these three plasticity types using non-model teleost species, in an attempt to shed light into key aspects of plasticity. In Chapter I, I describe the transcriptomic changes involved in the acute phenotypic plasticity of a euryhaline fish, the Arabian pupfish, in response to an increase in water salinity over a timeline. Osmoregulation and immune system were found to be crucial for long-term seawater adaptation, while in the short-term, cellular stress response mechanisms were activated. Tissue remodeling processes were also transiently elicited, equipping the fish with modifications necessary for acclimation to the new environment. Chapter II and Chapter III explore the effects of developmental and transgenerational phenotypic plasticity in a coral reef fish, the spiny damselfish, exposed to simulated ocean warming. In Chapter II, I tackle the fundamental question of the importance of timing in the transmission of transgenerational effects. I discovered that a developmental exposure of parents to warming might contribute to adaptive transgenerational plasticity, by adjustment of energy production pathways and gene expression regulation. Conversely, the exposure to warming during reproduction has no beneficial effects, but rather causes stress response mechanisms in the parents themselves and in their offspring. Finally, in Chapter III I disentangle the individual paternal and maternal contributions to the transmission of transgenerational plasticity. Fathers and mothers were found to elicit common but also parent-specific effects. Parent-specific transgenerational mechanisms involved in acclimation to warming included maternally influenced changes in lipid metabolism and paternally inherited epigenetic stress-response mechanisms. However, potentially maladaptive parental condition-transfer signatures were also observed, especially when the parental thermal histories did not coincide. Taken together, this dissertation provides novel information regarding the molecular mechanisms underlying phenotypic plasticity. A deeper understanding of these processes is critical to make predictions on species acclimation potential in a rapid-changing world.
Date of AwardJun 2022
Original languageEnglish (US)
Awarding Institution
  • Biological, Environmental Sciences and Engineering
SupervisorChristian Voolstra (Supervisor)

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