Electronic Supplementary Material (ESM)

Mechanistic basis of adaptive maternal effects: egg jelly water balance mediates embryonic adaptation to acidity in Rana arvalis

Longfei Shu1, Marc J-F Suter2, Anssi Laurila3 and Katja Räsänen1

Affiliations:

1Eawag, Department of Aquatic Ecology, Switzerland and ETH Zürich, Institute of Integrative Biology, Switzerland

2Eawag, Department of Environmental Toxicology, Switzerland and ETH Zürich, Department of Environmental Systems Science, Switzerland

3Animal Ecology/Department of Ecology and Genetics, Evolutionary Biology Center, Uppsala University, Sweden

Corresponding author:

Longfei Shu

Eawag, Department of Aquatic Ecology, Switzerland and ETH Zürich, Institute of Integrative Biology, CH-8600 Dübendorf, Switzerland

Email:

Supplementary

Figure S1 Map of the location of the study populations. Map of Sweden showing the geographic variation in anthropogenic lake acidification in 1990 (Swedish environmental protection agency).

Figure S2 Dry jelly mass of R. arvalis clutches.

In general, the populations differ in dry jelly mass, as indicated by the strong population main effect (Table S1). The egg coats of the B population contained much more dry jelly than those in S and T populations, while T population had least dry jelly (all population pairwise Tukey tests: P < 0.001). However, dry jelly mass did not differ significantly across different pHs and there was no pH × Population interaction (Table S1). These data highlighted the need to correct for differences in jelly dry mass between populations (i.e. results for relative water content in main manuscript; Fig 2b), but also indicate that differences in jelly dry mass across treatments have not biased our inferences on jelly water balance in response to different pH treatments. The reasons behind population differences in jelly dry mass are unclear. Site B has been limed since 1989 to counteract acidification and it is, therefore, possible that liming has had a potential influence on jelly amount (dry mass). However, this needs to be investigated in future study.

Table S1 General linear mixed models of dry jelly mass in three R. arvalis populations (acid, intermediate and neutral origin) under pH 4.0, 7.5 and 10 treatments. Significant effects (P < 0.05) are highlighted in bold.

df / F / P
Random effects
Family (Population) / 12 / 0.791 / 0.175
Fixed effects
pH Treatment / 2 / 1.020 / 0.346
Population / 2 / 538.576 / < 0.001
Population × pH Treatment / 4 / 1.618 / 0.175

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