Physiological and morphological growth and hydraulic measures in Asclepias syriaca and A. speciosa under drought
Data files
Dec 16, 2024 version files 109.10 KB
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2019_Milkweed_GH_Drought.xlsx
41.48 KB
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2019_Milkweed_Leaf_width_data.xlsx
21.95 KB
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Milkweed_LiCor_Data.xlsx
14.42 KB
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Milkweed_Stomatal_gs_density_and_length.xlsx
11.86 KB
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README.md
4.24 KB
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Wilting_and_root_Combined_data_set.xlsx
15.16 KB
Abstract
Understanding factors that determine a species’ geographical range is crucial for predicting climate-induced range shifts. Two milkweed species, Asclepias syriaca and Asclepias speciosa, have overlapping ranges along a moisture gradient in North America and are primary food sources for endangered monarch caterpillars. With decreasing moisture, long-lived species often exhibit slower growth and greater drought tolerance while many annual species exhibit faster growth strategies. Using this fast-slow framework, we assessed whether traits of these two sister species differ along a fast-slow growth continuum and could explain their distributions. We measured leaf and root functional traits in common gardens and greenhouse experiments. In key measures indicative of drought tolerance (e.g., growth, transpiration, and water potentials) the species were nearly identical. Contrary to expectations, A. speciosa did not exhibit greater drought tolerance, raising the question of how it survives in the more arid west. A reciprocal transplant study showed selection against A. syriaca in the western garden and that A. speciosa was better able to avoid seedling mortality. Focusing on seedling establishment, we found that A. speciosa exhibited faster deep root development and a narrow leaf phenotype associated with slower wilting and delayed drought-induced mortality. Rather than differences on the fast slow growth spectrum, our results indicate that A. speciosa avoids drought through faster deep root growth and a slower wilting phenotype. Our study suggests that A. syriaca’s range is limited by its drought tolerance, while A. speciosa employs a number of drought avoidance strategies to survive in more arid environments.
README: Asclepias syriaca and speciosa drought tolerance
https://doi.org/10.5061/dryad.0cfxpnwbx
Description of the data and file structure
Files and variables
File: 2019_Milkweed_Leaf_width_data.xlsx
Description: Contains plant height and leaf width information for genotypes of A. speciosa and A. syriaca collected from South Dakota and Minnesota. Latitude and longitude of collection sites are given. Leaf width was measured on different leaves for each plant 3x and averaged. Cells with N/A for plant height or leaf width measures indicate a plant that did not germinate or plants that only had one or two leaves for measurement.
Variables:
- Plant height (cm)
- Leaf width 1 (mm)
- Leaf width 2 (mm)
- Leaf width 3 (mm)
- Leaf width Average (mm)
File: Milkweed_LiCor_Data.xlsx
Description: Gas exchange data using a LiCor 6400 system are given for genotypes of A. speciosa and A. syriaca measured in September of 2020 or March of 2021. Latitude and longitude of where the milkweed were collected are also given. The missing values dark respiration values for March are due to the student forgetting to take the dark respiration measures.
Variables
- Amax or maximum assimilation rate (µmol m⁻² s⁻¹)
- Dark Respiration (µmol m⁻² s⁻¹)
- Quantum Yield (μmol m⁻² s¹ CO2 / μmol m⁻² s-¹ light
- A/gs or Assimilation/stomatal conductance (µmol mol⁻¹)
- Ci or Internal CO2 (ppm)
- gs or Stomatal Conductance (mol m⁻² s-¹)
- E or Transpiration (mol m⁻² s-¹)
- A/E or Assimilation/transpiration (μmol mol⁻¹)
File: Milkweed_Stomatal_gs_density_and_length.xlsx
Description: Contains stomatal density and length information for genotypes of A. speciosa and A. syriaca collected from South Dakota and Minnesota. Latitude and longitude of collection sites are given.
Variables
- Stomatal Length (mm)
- Stomatal Density (# Stomata/mm2)
File: Wilting_and_root_Combined_data_set.xlsx
Description: Contains information on the time for roots to reach the bottom of 22 cm pot and # days until wilting for genotypes of A. speciosa and A. syriaca collected from across the United States. Latitude and longitude of collection sites are given. The missing value for # of days for roots to reach bottom was for one plant whose roots never did reach the bottom. The missing values for biomass was for the last batch of plants which were accidentally thrown away before their weights were recorded.
Variables
- Plant Height (cm)
- Leaf width (mm)
- The # Leaves
- Total Plant Biomass (g)
- The # of days since stopped watering until plants wilted
- The # of days for roots to reach bottom of 22 cm tall pots
File: 2019_Milkweed_GH_Drought.xlsx
Description: Contains information on the variables measured for a greenhouse drought experiment for genotypes of A. speciosa and A. syriaca collected from South Dakota. Latitude and longitude of collection sites are given. There were four water treatments (High, Medium High, Medium Low, and Low) and the plants were randomized within four blocks. The missing values within the data set (N/A) are mostly the result of only a subset of the plants be measured for a particular variable (for example leaf area, vessel area, vessel density, water potential etc.).
Variables
- Biomass (g)
- Leaf weight (g)
- Leaf area (sm2)
- Specific leaf area (m2 kg-1)
- Average Transpiration (kg day-1)
- Average % Extraction (The soil pot weight divided by saturated pot weight)
- Total Transpiration (kg) water transpired over experiment
- Average xylem vessel area (mm2)
- Average xylem vessel density (#vessels mm-2)
- Total Root weight (g)
- root:shoot
- Root length (cm)
- Fraction Fine roots (%)
- Fine root weight (g)
- Leaf area:fine root
- Water use efficiency (g biomass/kg water)
- Transpiration divided by leaf area (ELA Kg day-1 m-2)
- Predawn water potential (bars)
- midday water potential (bars)
- Leaf area:root length
Missing data: N/A
Code/software
All the data files are MS Excel. They can be viewed in Excel or google sheets.
Methods
The data sets are a combination of greenhouse experiments and field studies.