Small-scale genetic differentiation in mean flowering time, but not in plasticity, along a geothermal heating gradient

Genetic differentiation in traits is assumed to frequently occur in response to divergent natural selection. For example, developmental traits might respond to differences in climate. However, little is known about when and at which spatial scales environmental differences lead to genetic differentiation, and to what extent there is genetic differentiation also in trait plasticity. Using a crossing design and a greenhouse heating experiment, we investigated genetic differentiation in the thermal sensitivity of flowering time in a perennial herb along small-scale gradients in geothermal soil heating in Iceland. We found additive genetic variation in both flowering time and thermal plasticity of flowering time. Genetic differentiation in the median flowering date of individuals showed a counter-gradient pattern; flowering being earlier at higher greenhouse temperatures, while at a given temperature individuals originating from warmer soils flowered later than individuals from colder soils..., The study was conducted with plants originating from Hengill, a sub-arctic geothermal area in SW-Iceland, where. The study area (ca. 1 km2) shows large gradients of soil temperature (e.g. ranging from geothermal heating to > 20°C above ambient temperature over 10-20 meters), without significant differences in other abiotic factors. In this area, we selected individuals of Cerastium fontanum that represented the entire temperature gradient. Soil temperature was measured in the immediate vicinity of each individual and fruits were collected from flowering individuals. The seeds were then sown in a greenhouse at Stockholm University (SU), and seedlings were moved to a common garden at SU, and kept there for two years. We then used a North Carolina type II (NCII) crossing design to investigate genetic differences in flowering time and in thermal plasticity of flowering time among individuals originating from different temperature environments. Seeds from each of the crosses were shown in..., , # Small-scale genetic differentiation along a geothermal heating gradient suggests local adaptation in mean flowering time but not in plasticity

[https://doi.org/10.5061/dryad.fxpnvx111](https://doi.org/10.5061/dryad.fxpnvx111)

This dataset comprises data from a crossing design and a greenhouse warming experiment used to investigated genetic differentiation in thermal sensitivity of development in a perennial herb along steep gradients in geothermal soil heating on Iceland.

## Description of the data and file structure

The file \"data_exp.csv\" contains data on flowering phenology of plants originating from crossings. Below is a description of each variable:

* unique_id: Unique identifier for each plant obtained from the crossings
* temp_dam: Temperature at the site of origin of the dam (ºC)
* temp_sire: Temperature at the site of origin of the sire (ºC)
* treat: Greenhouse experimental treatment (control or heated)
* total_n_fl: Total number of flowers
* FFD: First flowering date
* ...