DOI: 10.5061/dryad.mgqnk9961
title: Evolution in a rare plant in response to drought

description: As climate change continues and the frequency and intensity of droughts
 become more prevalent in some regions, plant populations are facing
 greater ecological pressures. The objective of this study was to observe
 the response of a rare plant species to an extreme drought event
 associated with climate change. To study this response, we collected seeds
 from three populations of Collinsia multicolor (San Francisco collinsia,
 Plantaginaceae) found in central California both before and after the
 state's historic 2012- 2016 drought. We used a greenhouse study to
 examine contemporary evolution between the collection years, and included
 a drought treatment to study plasticity. We measured three traits that
 indicate life history, morphological, and physiological responses to
 drought, including flowering time, stomatal density, and chlorophyll
 fluorescence. In our two coastal populations, where interannual moisture
 variation is greatest, we observed evolution only in stomatal density,
 while we observed plasticity in all measured traits. In contrast, our
 driest inland population showed no response to the drought or to our
 watering treatments, which is consistent with other studies that have
 found less response to drought in pre-adapted populations. Overall, our
 results suggest that plasticity is favored in variable environments.
 However, they also highlight that the pace evolution may be insufficient
 to respond to current environmental change.cont
description: # Evolution in a rare plant in response to drought
 [https://doi.org/10.5061/dryad.mgqnk9961](https://doi.org/10.5061/dryad.mgqnk9961) ## Description of the data and file structure Data were collected in a greenhouse study to examine the impacts of an extreme drought in central California from 2012-2016 on a rare plant species. The species studied was San Francisco Collinsia (Collinsia multicolor, Plantaginaceae). Seeds were collected from three populations in 2013, when the drought was first beginning, and again in 2017 or 2018, when the drought had ended. Differences in post-drought seed collection years were due to population accessibility. Field-collected seeds were grown in a greenhouse together under similar conditions and allowed to flower and set seed. By growing plants under the same conditions, we were able to remove any differences between plants due to duration of seed storage or maternal resource investment. The resulting seeds were planted in a greenhouse and used as the experimental generation. Measured traits included the number of days to first flower, stomatal density of leaves, and light-adapted chlorophyll fluorescence of leaves. Evidence for evolution was determined by looking at differences between pre- and post-drought plants within each population. A watering treatment was included in the experiment to determine whether the three populations varied in response to water availability. ## Data labels: Parent code: This label applies a unique code to each plant grown in the experiment. It includes the codes for population of origin (Anderson Dam =AD, Northern Swanton = NS, or Southern Swanton = SW), year of seed collection (2013, 2017, or 2018), watering treatment (dry or wet), parental line (a number designating the parent plant from which the seeds for the experimental generation were collected), and the offspring code (either A or B, representing the two seeds planted from each parental line in each of the watering treatments). Population: The names of each of the 3 populations (Anderson Dam, Northern Swanton, and Southern Swanton) Population code_1AD_2NS_3SS: A numerical code associated with each of the populations (Anderson Dam = 1, Northern Swanton = 2, Southern Swanton = 3) Drought: Whether seeds were collected in the field from before or after the drought event. Predrought = 2013, post-drought = 2017 or 2018 (depending on the population) Drought code_1pre_2post: A numerical code associated with the drought variable (previous column). 1 = predrought = 2013, 2 = post-drought = 2017 or 2018 Treatment: The watering treatments to study plasticity. dry = low water, wet = well-watered Treatment code_2drought_1water: A numerical code associated with the watering treatment (pervious code). 2 = dry = low water, 1 = wet = well-watered Parent = A numerical code indicating the parental line from the field collected seeds which was used for the experimental plant Sow date: The date on which seeds were sown Germ_totals: A code indicating whether seeds germinated. 1 = yes, 2 = no Germinated: A word indicating whether seeds germinated (Yes or no) Germ_date: The date on which seeds germinated. "N/a" indicates no germination. Daysbtw_Sow_Germ: The number of days between sowing seeds and germination. "N/a" indicates no germination. First_Flower_Date: The date on which the first flower opened. "N/a" indicates no flowering. Daysbtw_sow_FirstFlower: The number of days between sowing seeds and the first flower opening. "N/a" indicates no flowering. Daysbtw_germ_firstflower: The number of days between germination and first flower opening. "N/a" indicates no flowering.Flowered: A word indicating whether plants flowered (Yes or no) Flowered_0no_1yes: A numerical code indicating whether plants flowered (0=no, 1=yes) Survived: A statement indicating whether plants survived the experiment (yes or no) Stomatal_density: The average number of stomata per unit leaf area, based on measurements of 5% of the leaf (# / mm^2) PhiPs2_Value: Chlorophyll fluorescence, an indicator of photosynthetic efficiency of photosystem II, indicating the proportion of absorbed light used for photosynthesis.