The timing of seed germination determines the environment experienced by a plant’s most vulnerable life stage—the seedling. Germination is environmentally cued, and genotypes can differ in their sensitivity to environmental cues. When genotypes differ in their response to cues, and when cues accurately predict the post-germination environment, the post-germination environment experienced by seedlings can itself have a genetic basis and potential to evolve. We tested for genetic differences in the post-germination environment using Arabidopsis thaliana genotypes that vary in seed dormancy, a trait known to alter germination time. We dispersed seeds into the field in five seasonal cohorts over 1.5 years, observed germination timing for 5297 individuals, and measured the soil temperature and moisture experienced by individuals throughout their life cycle. We found that genotypes differed in the environments they experienced during seedling establishment. This environmental variation occurred because genotypes differed in their environmental sensitivity to germination cues, and pre-germination cues were correlated with post-germination environments. Seeds exhibited temporal habitat selection by germinating into a non-random subset of environmental conditions available, and seed dormancy increased the consistency of habitat selection. Strikingly, the post-germination environment affected fitness by altering the probability of seedling survival, such that genotypes that engaged in stronger habitat selection were less likely to reach reproduction. Our results suggest that environmentally-cued development may be a widespread mechanism by which genotypes can differ in the environment they experience, introducing the possibility that the environment itself can be inherited and can evolve.
1. environmental data
Hourly soil temperature (degrees C) and soil moisture (m^3 water/m^3 soil) recorded for the duration of our experiment (November 2011 to July 2013). Data were obtained using Onset HOBO data loggers, and one sensor for each environmental variable was placed at each of 12 spatial blocks. Columns D-O represent soil temperature for each individual block, while columns P to AA represent soil moisture for each individual block.
2. germination data
Germination date for 5297 individual seedlings observed in our study. Seeds were dispersed in 5 seasonal cohorts over the course of 1 full year (“Dispersal”). Block refers to each of 12 spatial blocks, and row and column represent the spatial position within each block. The majority of the data in this file come from germination pots (“Pot_type”); however, if no seeds germinated in the germination replicate within the block, we included germination data from the life-history pot for that particular genotype and treatment combination. Thus, some “life-history” pots are included in the dataset. Genotype refers to one of eight genotypes included in the study. Mat refers to the temperature (degrees C) experienced by maternal plants before seeds were dispersed. Germ Date represents the date the seedling was first observed in the field. Number of seedlings per pot is calculated for each pot ID, and thus is not unique to each seedling. The experimental design included a dispersal of 15 seeds per pot; however, because seeds are extremely small, in some pots greater than 15 seeds were dispersed.
3. life history and fitness data
Life history and fitness data for 418 focal individuals observed in our study. Seeds were dispersed in 5 seasonal cohorts over the course of 1 full year (“Dispersal”). Block refers to each of 12 spatial blocks, and row and column represent the spatial position within each block. Data come exclusively from life-history pots. Genotype refers to one of eight genotypes included in the study. Mat refers to the temperature (degrees C) experienced by maternal plants before seeds were dispersed. Dispersal date represents the calendar date when seeds were placed in the field, while germination date, bolt date, flower date, 90% seed maturation, and dead date represent the first date during which these developmental stages were observed. Days to germ represents the number of days from dispersal until germination, while days to bolt, flower, mature, and death (lifespan) represent the number of days between germination and the first observation of each developmental stage. Survival to flowering is binary; 0 = individual died before reproduction; 1= individual survived to flowering. Flowering time represents the number of days from germination until appearance of the first flower. Flowering interval represents the number of days from appearance of the first flower until 90% seed maturation. Fecundity represents total number of siliques produced. Number of unique treatment combinations (n=413) is slightly lower than total number of focal individuals (n=418), as five treatment combinations included two replicate pots within a single block.
3. fitness data (life history pots).csv