Egg size and offspring phenotype data at early life stages in seven Arctic charr morphs ...

• Main Authors: Beck, Samantha V., Räsänen, Katja, Kristjánsson, Bjarni K., Skúlason, Skúli, Jónsson, Zophonías O., Tsinganis, Markos, Leblanc, Camille A.
• Format: Dataset
• Language: English
• Published: Dryad 2022
• Subjects: FOS Natural sciences; developmental plasticity; diversification; egg size; freshwater; maternal effects; resource polymorphism; Salvelinus alpinus; Arctic; Arctic charr
• Online Access: https://dx.doi.org/10.5061/dryad.jh9w0vtfg; https://datadryad.org/stash/dataset/doi:10.5061/dryad.jh9w0vtfg

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 characterised 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 ... : Female size and egg size data were measured on wild-collected females and embryos reared in temperature-controlled laboratory conditions. To characterise variation in size and developmental times, morphs were sampled at four points during development: 1) post-fertilisation (PF); eye stage (E); hatching (H); and first feeding (FF). Mean egg size per female was estimated by measuring egg diameter of embryos at PF and E stages. Average measurements of offspring size and DD were taken for each female at H and FF. See manuscript for further details on methodology. ...