DOI: 10.5061/dryad.x95x69px4
title: Plastic response in amphibious plant functional traits along a latitudinal (climate) gradient

description: This dataset supports an investigation into the variation of vegetative
 and reproductive traits of six plant species characteristic of
 Mediterranean temporary ponds, Baldellia ranunculoides, Damasonium
 bourgaei, Damasonium polyspermum, Elatine brochonii, and Isoetes velata,
 across a 750-km north-south latitudinal (climate) gradient (31°-35° N) in
 Morocco (mean annual precipitation range 264 to 856 mm). Selected
 vegetative (height, number of leaves, leaf area) and reproductive (number
 of fruits, number of seeds/spores per fruit, number of seeds/spores per
 plant, seed/spore size and seed mass) traits of these six species were
 assessed on both field-collected specimens and on plants grown from
 seeds/spores in mesocosms under uniform experimental conditions. We
 hypothesized that the observed differences in functional traits
 (vegetative and reproductive) among populations mainly reflect phenotypic
 plasticity to variable environmental conditions. This work was possible
 thanks to the scientific permit (N° 241 HCEFLCD/DLCDPN/DPRN/CFF) granted
 by the Agence Nationale des Eaux et Forêts (Morocco).
description: <strong><em>Traits of plants from natural
 populations</em></strong> For each species,
 10 individuals per population were randomly collected at the end of their
 cycle (June–July 2014). Three vegetative traits (height, leaf number, and
 area) and five reproductive traits (fruit count, seeds per fruit, seeds
 per plant, seed size, and mass of 40 seeds) were measured for each
 individual. Here, "fruit" includes Isoetaceae sporangia, and
 "seeds" include spores.
 <strong><em>Traits of plants grown in common
 garden </em></strong> A common garden
 experiment examined trait variation among populations of six species under
 uniform light, temperature, hydrology, and substrate. Plants grew from
 seeds (Spermatophytes) or sporangia (Lycopodiophytes) collected from 10
 individuals per species per pond at the end of their cycle. Mean seed mass
 (n = 40) was measured before the experiment. In
 transparent plastic pots (8 cm diameter, 12 cm height), a layer of
 synthetic cotton wool was placed at the bottom and then covered with 4 cm
 of temporary pond sediment that was first sterilized (120 °C during 24
 hours). To increase the chance of having at least one germination, three
 seeds from the same population were planted in each pot which was flooded
 with 2 cm of tap water. For each species, 10 replicates per population
 were set up (270 pots total). Pots were randomly placed in a sunlit lab,
 watered daily (2 cm depth), and fully randomized weekly. Temperature was
 recorded weekly. Every three weeks, vegetative traits were measured on
 three individuals per pot, then averaged. After nine months, fruits per
 plant were counted. To assess other reproductive traits, four dried fruits
 per plant were analyzed for seed count, size, and mass (40
 seeds). <strong><em>Data
 analysis</em></strong> Trait associations
 in natural populations were analyzed using a correlation matrix. Spearman
 correlations examined relationships between traits and pond latitude for
 both field-collected and laboratory-grown plants across all six species. A
 similar approach was used to assess the relationship between traits and
 rainfall, separately for individuals collected in the field and for plants
 cultivated in the laboratory. To visualize trait
 variation in each of the six species across regions, principal component
 analyses (PCA) were conducted separately for field and cultivated plants.
 Spearman correlations assessed the relationship between population
 coordinates on PCA axis 1 and latitude. Functional trait differences
 between regions were tested using one-way ANOVA for each
 species. To quantify the phenotypic plasticity of the
 plants investigated in this study, we used the Relative distance
 plasticity index (RDPI) which allows statistical comparisons of plasticity
 between species for each trait (Valladares et al., 2006). The function
 ‘rdpi’ of the R package ‘Plasticity’ was adapted for phenotypic plasticity
 computing on the basis of phenotypic distances among individuals of the
 same species under different environments. RDPI ranges
 from 0 (no plasticity) to 1 (maximal plasticity) and is calculated as
 follow:   <strong>RDPI = ∑(d
 ij →i′j′/(x i′j′ + x ij ) )/n</strong>
 where: xij: is matrix of a specific trait x (i
 row and j column)  i: is a given level of the
 environmental treatment (latitude)  j: is to the
 individual number identification  d ij→i′j′: absolute
 value of distances between all pairs of individuals from the same species
 under different environments x i′j′ + x ij:  sum of
 trait values of all pairs of individuals from the same species under
 different environments n:  is the total number of
 distances Differences of RDPI values for each trait
 between species were evaluated with one-way ANOVA and <em>post hoc
 </em>Tukey mean comparison test using R software.
 Species' investment preference (reproductive or vegetative)
 was analyzed using Spearman correlation between latitude and the seed
 mass/plant height ratio. These traits were chosen as the strongest
 indicators of reproductive and vegetative investment (Table 2).
 Multivariate and univariate analyses were performed using
 STATISTICA 10 (StatSoft Inc., Tulsa OK, USA).
description: # Plastic response in amphibious plant functional traits along a
 latitudinal (climate) gradient Dataset DOI:
 [10.5061/dryad.x95x69px4](10.5061/dryad.x95x69px4) ## Description of the
 data and file structure Twenty temporary ponds across six regions
 (Tangier, Mamora, Benslimane, Chaouia, Jbilets, and Essaouira) were
 selected along a 750 km north-south gradient (35°–31°N). This gradient
 aligns with increasing aridity, as annual rainfall decreases from 856 mm
 in the north to 264 mm in the south. We hypothesized that the differences
 between populations in observed functional traits (vegetative and
 reproductive) result from plastic response to the variable environment
 rather than of a local genetic adaptation. ### Files and variables ####
 File: Field_and_experiment_data_El_Madihi_et_al_oikos-2026.xlsx
 **Description: 2 sheets** **Description of sheet 'Plant
 traits'**  ##### Variables * Type: (2 values “Field” and “Experiment”
 for data from plants collected in the wild or grown in mesocosm in common
 garden conditions respectively * Pond code: identifies each pond (20) *
 Species: identifies plant species (6) * Replicate: 10 randomly selected
 plants for each pond and species * Region: identifies the region (6) where
 the ponds are located * Height (cm): individual plant height * Number of
 leaves for each individual plant * Leaf area: mean surface area of
 individual leave (calculated as the Length X width on 3 leaves per plant)
 * Number of fruits per plant * Seed weight (40 seeds / spores) calculated
 as the mean value of 4 fruits/plant * Number of seeds per fruit calculated
 as the mean value of 4 fruits/plant * Seed size: Length X width (mean of 5
 replicates) * Number of seeds per plant: sum of the number of seeds per
 fruit The sheet “Pond information” contains 10 columns with the following
 information: **Description of sheet 'Pond information'**  * Pond
 code (20): identifies each pond * Région (6): identifies the region where
 the pond is located * Latitude: identifies the latitude of the pond. Exact
 coordinates of the ponds are not provided as they contained endangered
 species IUCN RedList): *Damasonium polyspermum*: VU, *Isoetes setacea* (=
 *I. delilei*): NT; *Baldellia ranunculoides*: NT; *Elatine brochonii*: NT)
 * Precipitation: mean annual rainfall (mm) * The following columns (E-J)
 shows for each pond what species were used for trait analysis both in the
 field and in experimental conditions. 'Null' n the cells means
 that the corresponding species was not studied in that pond. ####
 **Description of file 'plasticity_analysis.R'**  * Multivariate
 and univariate analyses were performed using STATISTICA 10 (StatSoft Inc.,
 Tulsa OK, USA). * To quantify the phenotypic plasticity of the plants
 investigated in this study, we used the Relative distance plasticity index
 (RDPI) which allows statistical comparisons of plasticity between species
 for each trait (Valladares et al., 2006). The function ‘rdpi’ of the R
 package ‘Plasticity’ was adapted for phenotypic plasticity computing on
 the basis of phenotypic distances among individuals of the same species
 under different environments. Differences of RDPI values for each trait
 between species were evaluated with one-way ANOVA and *post hoc* Tukey
 mean comparison test using R software.