Abstract 1. Adaptive radiation in fishes has been actively investigated over the last decades. Along with numerous well-studied cases of lacustrine radiation, some examples of riverine sympatric divergence have been recently discovered. In contrast to the lakes, the riverine conditions do not provide evident stability in the ecological gradients. Consequently, external factors triggering the radiation, as well as developmental mechanisms underpinning it, remain unclear. 2. Herein, we present the comprehensive study of external and internal drivers of the riverine adaptive divergence of the salmonid fish Salvelinus malma. In the Kamchatka River, N-E Asia, this species splits in the reproductively isolated morphs that drastically differ in ecology and morphology: the benthivorous Dolly Varden (DV) and the piscivorous Stone charr (SC). 3. To understand why and how these morphs originated, we performed a series of field and experimental work, including common-garden rearing, comparative ontogenetic, physiological and endocrinological analyses, hormonal "engineering" of phenotypes, and acute toxicological tests. 4. We revealed that the type of spawning ground acts as the main external factor driving the radiation of S. malma. In contrast to DV spawning in the leaf krummholz zone, SC reproduces in the zone of coniferous forest, which litter has a toxic impact on developing fishes. SC enhances resistance to the toxicants via metabolism acceleration provided by the elevated thyroid hormone content. These physiological changes lead to the multiple heterochronies resulting in a specific morphology and SC's expansion into a piscivorous niche. 5. Salvelinus malma represents a notable example of how the thyroid axis contributes to the generation of diverse phenotypic outcomes underlying the riverine sympatric divergence. Our findings, along with the paleoecology data concerning spruce forest distribution during the Pleistocene, provide an opportunity to reconstruct a scenario of S. malma divergence. Taken together, obtained results with the data of the role of thyroid hormones in the ontogeny and diversification of fishes contribute a resource to consider the thyroid axis as a prime director orchestrating the phenotypic plasticity promoting evolutionary diversification under the changing environmental conditions. 06-Jan-2021

The supplements are tables of primary data obtained during the field works and the experiments on Dolly Varden (Salvelinus malma) rearing. This species is not an endangered or protected species in the Russian Federation. Following the Federal law “On Fisheries and Conservation of Aquatic Biological Resources” №166-ФЗ, the non-commercial fishing of Dolly Varden charr does not require any permissions. All field and experimental procedures with fish were carried out according to the guidelines and following the laws and ethics of the Russian Federation and approved by the ethics committee of the Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences.

This folder contains the data file for the article:

    Esin, E. V., Markevich, G. N., Melnik, N. O., Kapitanova, D. A. and F. N. Shkil (2021). Natural toxic impact and thyroid signaling interplay orchestrates riverine adaptive divergence of salmonid fish. Journal of Animal Ecology

We investigated how thyroid signaling can control a diverse range of outcomes, various adaptive phenotypic novelties and riverine sympatric divergence. Our results along with the data concerning thyroid involvement in the diversification of various fish groups indicate that thyroid axis orchestrates the subtle phenotypic plasticity in fish promoting evolutionary diversification under shifting environmental conditions.

Comments and requests should be addressed to Evgeny Esin: evgesin@gmail.com. All material is free of use, but I would appreciate this dataset and the matching paper cited if appropriate.

The file named JAE_Esin_etal_2021(.XLS format)contains source data sets for the final version of the manuscript. The file is divided into five sheets containing different independent data blocks:

Sheet 1 contains the data on full length (in mm) and total weight (in g; mean values at the end of columns are marked red) of all experimental fish groups including common-garden experiment and thyroid alteration experiment. The data was used in fig. 2.

Sheet 2 contains the data on the total thyroid (T3) concentrations (in ng / g) in the extract of a whole fish from the common-garden experiment, thyroid alteration experiment and the experiment with the conifer infusion impact. All experimental groups and its age in day*degrees are marked. The hormone concentrations were evaluated by enzyme-linked immunosorbent assay (ELISA) barbital-free procedure adapted from Schnitzler et al. (2008, doi: 10.1016/j.marpolbul.2008.06.011). The data was used in fig. 1.

Sheet 3 contains the data on three physiological parameters (i.e. glucose concentration in the blood (in mmol/L), antioxydant activity of tissues (in mU/L) and phospholipid concentration in the muscles (in g/L)) of the experimental fish. All experimental groups and its age in day*degrees are marked. The data was used in fig. 3.

Sheet 4 contains the data on the ossification ranks of several cranial bones: supraethmoid (set), frontal (fro), parasphenoid (phsp) and orbital series (orbita) bones; premaxilla (pmx), maxilla (mxl), dentary (den), and vomer (vom); alveolar teeth formulae on palatine (pal) and lingual bones (glo), the number of ossified sections (osb) and rakers (sb) of the first gill arch. All experimental groups and its age in day*degrees are marked. Mean values of the ranks are marked red. The data was used in fig. 5.

Sheet 5 contains the data on the linear morphometric measurements (in pixels) of fish from the common-garden experiment and thyroid alteration experiment. All experimental groups and its age in day*degrees are marked. The data complements fig, 4, b and с.