DOI: 10.5061/dryad.fxpnvx111
title: Data from: Small-scale genetic differentiation in mean flowering time, but not in plasticity, along a geothermal heating gradient

description: 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. We found
 no corresponding pattern for plasticity, suggesting that genetic
 differentiation in phenology in response to soil heating has occurred
 through changes in trait means rather than in plasticity. Findings such as
 these, identifying genetic trait differentiation along an environmental
 gradient are key to understanding how environmental variation can drive
 the process of local adaptation, and to predict responses to future
 environmental changes.
description: The study was conducted with plants originating from Hengill, a
 sub-arctic geothermal area in SW-Iceland, where. The study area (ca. 1
 km<sup>2</sup>) shows large gradients of soil temperature
 (e.g. ranging from geothermal heating to &gt; 20°C above ambient
 temperature over 10-20 meters), without significant differences in other
 abiotic factors. In this area, we selected individuals
 of <em>Cerastium fontanum</em> 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 the greenhouse and seedlings were kept in the common garden until
 the next year, when a heating experiment was performed in the greenhouse,
 including two different treatments: a heated treatment mimicking soil
 heating and a control treatment with ambient temperatures. For each
 individual in the experiment, we recorded the total number of flowers
 produced and three measures of flowering phenology (first, median, and
 last flowering date).
description: # 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 * LFD: Last flowering date * MFD: Median flowering date * dam: Identifier of the plant used as dam * sire: Identifier of the plant used as sire * dam_sire: Identifier of the crossing (dam x sire) * Missing data: NA ## Code/Software The file "code_greenhouse_experiment.Rmd" is an R notebook containing all the code needed to replicate the analyses in the manuscript. It has been created using R version 4.3.4 and the R packages "tidyverse", "readxl", "ggeffects", "knitr", "lme4", "lmerTest", "gridExtra", "ggthemes", "sjPlot", "cowplot", "performance", "partR2" and "ggh4x".