Biotic interactions promote local adaptation to soil in plants - Supplementary data

First, we show that several plant traits evolved in response to biotic interactions in a soil-specific way. Second, using a reciprocal transplant experiment, we demonstrate that significant local adaptation to soil-type evolved in the “number of open flowers”, a trait used as a fitness proxy, but only in plants that evolved with herbivory and bee pollination. Whole genome re-sequencing of experimental lines revealed that biotic interactions caused a 10-fold increase in the number of SNPs across the genome with significant allele frequency change, and that alleles with opposite allele frequency change in different soil types (antagonistic pleiotropy) were most common in plants with an evolutionary history of herbivory and bee pollination.

Our results demonstrate that the interaction with mutualists and antagonists can facilitate local adaptation to soil type through antagonistic pleiotropy.

Methods

Plant, Brassica rapa, phenotype and genotype were measured. Samples result from a 8 generations experimental evolution where selective agents were different soils, herbivory and pollinators (Dorey and Schiestl 2024). Sample size for trait measurements was 36 per replicate, this was chosen according to previous studies, and values published in the literature (Gervasi and Schiestl 2017, Ramos and Schiestl 2020, Dorey and Schiestl 2024).

For trait measurements and DNA extraction, we used all individuals if available (some plants lacked sufficient leaf tissue for DNA extraction).