Size‐dependent stress response in juvenile Arctic charr (<i>Salvelinus alpinus</i>) under prolonged predator conditioning

Kortet, Raine; Laakkonen, Mika; Tikkanen, Jouni; Vainikka, Anssi; Hirvonen, Heikki

doi:10.1111/are.14023

Cited by 7 publications

(3 citation statements)

References 88 publications

(138 reference statements)

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“…Given the importance of energy for all biological processes, an examination of how predators affect the ontogeny of various energetically significant traits, and their scaling with body mass, can provide valuable insights into age-and size-specific energy-allocation strategies (also see [22,130,150,151]).…”

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confidence: 99%

Effects of Fish Predators on the Mass-Related Energetics of a Keystone Freshwater Crustacean

Glazier

Borrelli

Hoffman

2020

Biology

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Little is known about how predators or their cues affect the acquisition and allocation of energy throughout the ontogeny of prey organisms. To address this question, we have been comparing the ontogenetic body-mass scaling of various traits related to energy intake and use between populations of a keystone amphipod crustacean inhabiting freshwater springs, with versus without fish predators. In this progress report, we analyze new and previously reported data to develop a synthetic picture of how the presence/absence of fish predators affects the scaling of food assimilation, fat content, metabolism, growth and reproduction in populations of Gammarus minus located in central Pennsylvania (USA). Our analysis reveals two major clusters of ‘symmorphic allometry’ (parallel scaling relationships) for traits related to somatic versus reproductive investment. In the presence of fish predators, the scaling exponents for somatic traits tend to decrease, whereas those for reproductive traits tend to increase. This divergence of scaling exponents reflects an intensified trade-off between somatic and reproductive investments resulting from low adult survival in the face of size-selective predation. Our results indicate the value of an integrated view of the ontogenetic size-specific energetics of organisms and its response to both top-down (predation) and bottom-up (resource supply) effects.

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confidence: 99%

Effects of Fish Predators on the Mass-Related Energetics of a Keystone Freshwater Crustacean

Glazier

Borrelli

Hoffman

2020

Biology

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“…Early rearing conditions can strongly modify the performance of fish juveniles, potentially inducing fitness‐related variability among genotypes (e.g., Hatanpää et al., 2020; Janhunen et al., 2010, 2016; Kortet et al., 2019). Genotype‐by‐environment interaction thereby plays an important role in preserving genetic variation of quantitative traits in natural and captive populations (Gillespie & Turelli, 1989; Mackay et al., 2009).…”

Section: Discussionmentioning

confidence: 99%

“…Early rearing conditions can strongly modify the performance of fish juveniles, potentially inducing fitness-related variability among genotypes (e.g., Hatanpää et al, 2020;Janhunen et al, 2010Janhunen et al, , 2016Kortet et al, 2019). Genotype-by-environment interaction thereby plays an important role in preserving genetic variation of For all other families, the initial number of fish was 42 + 35 in the hatchery + seminatural environment, respectively.…”

Section: Discussionmentioning

confidence: 99%

Selection among critically endangered landlocked salmon (Salmo salar m. sebago) families in survival and growth traits across early life stages and in different environments

Janhunen,

Eronen,

Kekäläinen

et al. 2024

Evolutionary Applications

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Endangered wild fish populations are commonly supported by hatchery propagation. However, hatchery‐reared fish experience very different selective pressures compared to their wild counterparts, potentially causing genotype‐by‐environment interactions (G × E) in essential fitness traits. We experimentally studied early selection in a critically endangered landlocked Atlantic salmon population, first from fertilization to the swim‐up stage in a common hatchery setting, and thereafter until the age of 5 months in two contrasting rearing environments. Swim‐up progeny were moved either to standard indoor hatchery tanks involving conventional husbandry or to seminatural outdoor channels providing only natural food. After the first summer, sampled survivors were assigned to their families by genotyping. Early survival until the swim‐up stage was mostly determined by maternal effects, but also involved significant variation due to sires and full‐sib families (potential genetic effects). High on‐growing survival in hatchery tanks (88.7%) maintained a more even distribution among families (relative share 1.5%–4.2%) than the seminatural environment (0.0%–5.4%). This heterogeneity was mostly maternal, whereas no independent paternal effect occurred. Heritability estimates were high for body size traits in both environments (0.62–0.69). Genetic correlations between the environments were significantly positive for body size traits (0.67–0.69), and high body condition in hatchery was also genetically linked to rapid growth in the seminatural environment (0.54). Additive and phenotypic growth variation increased in the seminatural environment, but scaling effects probably played a less significant role for G × E, compared to re‐ranking of genotypes. Our results suggest that not only maternal effects, but also genetic effects, direct selection according to the environmental conditions experienced. Consistently high genetic variation in growth implies that, despite its low overall genetic diversity and long history in captive rearing (>50 years), this landlocked Atlantic salmon population still possesses adaptive potential for response to change from hatchery rearing back to more natural conditions.

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Hormonal regulation of the phenotype into environmentally appropriate pace‐of‐life syndromes

Weidner,

Jensen,

Giske

et al. 2024

Fish and Fisheries

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The risk of predation is an important driver that tailors life histories in various ways. Using an evolutionary model based on hormonal control, we study how different predation regimes affect adaptive risk‐taking and growth in fish populations. Growth, metabolism and foraging in the modelled fish are regulated by three simplified hormone functions: growth hormone, orexin, and thyroid hormone. A dynamic state‐dependent optimization model finds optimal hormone profiles for adaptive growth strategies in juvenile fish. We consider a gradient from species where behaviour and metabolic activity have large consequences for risk (typically benthic and camouflaged species), to the opposite endpoint where behaviour may modify predation risk to a smaller degree (as in the pelagic). Along this gradient, the model predicts changes in the pace of life from slow to fast, enacted by up‐regulation of the three hormone functions which in turn increase foraging and metabolism and change the priorities of energy reserves versus growth. Under all types of predation risk investigated, growth is faster when food availability is higher. Energy reserves are maintained primarily during periods of poor food availability and are used to accelerate growth during periods when food availability is high. The thyroid hormone function is up‐regulated predominantly when food availability is high and has an important role in trade‐offs balancing energetic gain and survival. At the individual time scale, the hormone system improves organismic flexibility and robustness. Over the phylogenetic time scale, hormone system adaptations have also restricted the phenotypic plasticity of individuals.

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Size‐dependent stress response in juvenile Arctic charr (Salvelinus alpinus) under prolonged predator conditioning

Cited by 7 publications

References 88 publications

Effects of Fish Predators on the Mass-Related Energetics of a Keystone Freshwater Crustacean

Effects of Fish Predators on the Mass-Related Energetics of a Keystone Freshwater Crustacean

Selection among critically endangered landlocked salmon (Salmo salar m. sebago) families in survival and growth traits across early life stages and in different environments

Hormonal regulation of the phenotype into environmentally appropriate pace‐of‐life syndromes

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