Egg size and growth in steelhead<i>Oncorhynchus mykiss</i>

Self, Katharine E.; Schreck, Carl B.; Cogliati, Karen M.; Billman, Eric J.; Noakes, David L. G.

doi:10.1111/jfb.13764

Cited by 12 publications

(11 citation statements)

References 30 publications

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“…Better understanding the causes of phenotypic divergence at early life‐stages and the relationship between egg size and offspring phenotype and fitness − especially under differing dietary/ecological conditions − would shed light both on early stages of divergence along the speciation continuum (e.g., Nosil, ) as well as the evolution of optimal maternal investment in contrasting environments (e.g., Smith & Fretwell, ). The number of studies documenting egg size mediated effects on offspring phenotype in fishes is rapidly growing (Cogliati et al, ; Leblanc et al, ; Leblanc et al, ; Segers et al, ; Self, Schreck, Cogliati, Billman, & Noakes, ; Thorn & Morbey, ). At the same time, our knowledge as to whether egg size can influence evolutionary divergence is limited.…”

Section: Resultsmentioning

confidence: 99%

Gene expression in the phenotypically plastic Arctic charr (Salvelinus alpinus): A focus on growth and ossification at early stages of development

Beck

Räsänen

Ahi

et al. 2018

Evolution and Development

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Gene expression during development shapes the phenotypes of individuals. Although embryonic gene expression can have lasting effects on developmental trajectories, few studies consider the role of maternal effects, such as egg size, on gene expression. Using qPCR, we characterize relative expression of 14 growth and/or skeletal promoting genes across embryonic development in Arctic charr (Salvelinus alpinus). We test to what extent their relative expression is correlated with egg size and size at early life‐stages within the study population. We predict smaller individuals to have higher expression of growth and skeletal promoting genes, due to less maternal resources (i.e., yolk) and prioritization of energy toward ossification. We found expression levels to vary across developmental stages and only three genes (Mmp9, Star, and Sgk1) correlated with individual size at a given developmental stage. Contrary to our hypothesis, expression of Mmp9 and Star showed a non‐linear relationship with size (at post fertilization and hatching, respectively), whilst Sgk1 was higher in larger embryos at hatching. Interestingly, these genes are also associated with craniofacial divergence of Arctic charr morphs. Our results indicate that early life‐stage variation in gene expression, concomitant to maternal effects, can influence developmental plasticity and potentially the evolution of resource polymorphism in fishes.

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Section: Resultsmentioning

confidence: 99%

Gene expression in the phenotypically plastic Arctic charr (Salvelinus alpinus): A focus on growth and ossification at early stages of development

Beck

Räsänen

Ahi

et al. 2018

Evolution and Development

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“…Thus, the complex response of egg size to natural selection in wild populations of salmonids remains an evolutionary puzzle. Because ecological factors are important determinants of egg size and fitness of juvenile salmonids (e.g., Cogliati et al, 2018 ; Jonsson & Greenberg, 2022 ; Self et al, 2018 ), further work is needed to better characterize the environment both during maturation and during embryonic development.…”

Section: Discussionmentioning

confidence: 99%

Variation in egg size and offspring phenotype among and within seven Arctic charr morphs

Beck

Räsänen

Kristjánsson

et al. 2022

Ecology and Evolution

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Maternal effects have the potential to alter early developmental processes of offspring and contribute to adaptive diversification. Egg size is a major contributor to offspring phenotype, which can influence developmental trajectories and potential resource use. However, to what extent intraspecific variation in egg size facilitates evolution of resource polymorphism is poorly understood. We studied multiple resource morphs of Icelandic Arctic charr, ranging from an anadromous morph—with a phenotype similar to the proposed ancestral phenotype—to sympatric morphs that vary in their degree of phenotypic divergence from the ancestral anadromous morph. We characterized variation in egg size and tested whether egg size influenced offspring phenotype at early life stages (i.e., timing of‐ and size at‐ hatching and first feeding [FF]). We predicted that egg size would differ among morphs and be less variable as morphs diverge away from the ancestral anadromous phenotype. We also predicted that egg size would correlate with offspring size and developmental timing. We found morphs had different egg size, developmental timing, and size at hatching and FF. Egg size increased as phenotypic proximity to the ancestral anadromous phenotype decreased, with larger eggs generally giving rise to larger offspring, especially at FF, but egg size had no effect on developmental rate. The interaction between egg size and the environment may have a profound impact on offspring fitness, where the resulting differences in early life‐history traits may act to initiate and/or maintain resource morphs diversification.

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“…Egg size usually provides a reasonable proxy for the other traits potentially important for offspring survival, development and growth; like the amounts of water, nutrients, or energy contained in the egg (Berg et al, 2001;Salze et al, 2005). Hence, we often observe long-term cascading effects of egg size on early-life offspring performance (Segers and Taborsky, 2011;Self et al, 2018;Semlitsch and Gibbons, 1990). Measuring egg size is straightforward and can be performed in a non-invasive manner, usually recorded as diameter or wet mass (Brooks et al, 1997;Krist, 2011;Räsänen et al, 2005).…”

Section: Introductionmentioning

confidence: 97%

Egg size does not universally predict embryonic resources and hatchling size across annual killifish species

Vrtílek

Dooren

Beaudard

2020

Comparative Biochemistry and Physiology Part A: Molecular &

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Egg size has a crucial impact on the reproductive success of a mother and the performance of her offspring. It is therefore reasonable to employ egg size as a proxy for egg content when studying variation in offspring performance. Here, we tested species differences in allometries of several egg content parameters with egg area. We measured individual eggs in five species of annual killifish (Cyprinodontiformes), a group of fish where egg banks permit population survival over dry season.Apart from comparing allometric scaling exponents, amounts and compositions of egg components across the different species, we assessed the explanatory power of egg area for egg wet and dry weight and for hatchling size. We found notable species-specific allometries between egg area and the other egg parameters (egg dry weight and water content, elemental composition and triglyceride content).Across species, egg area predicted egg wet weight with highest power. Within species, coefficients of determination were largest in Austrolebias elongatus, a large piscivorous species with large eggs. Our study shows that systematically using egg area as a proxy of egg content between different species can ignore relevant species-specific differences and mask within-species variability in egg content.

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Egg size and growth in steelheadOncorhynchus mykiss

Cited by 12 publications

References 30 publications

Gene expression in the phenotypically plastic Arctic charr (Salvelinus alpinus): A focus on growth and ossification at early stages of development

Gene expression in the phenotypically plastic Arctic charr (Salvelinus alpinus): A focus on growth and ossification at early stages of development

Variation in egg size and offspring phenotype among and within seven Arctic charr morphs

Egg size does not universally predict embryonic resources and hatchling size across annual killifish species

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