Towards a moss sclerophylly continuum: Evolutionary history, water chemistry and climate control traits of hygrophytic mosses

Abstract

Mosses are amongst the oldest and simplest plants, they can be found almost everywhere in the world, and they condition the structure and function of many ecosystems. Their sensitivity to environmental changes makes them very interesting subjects of study in ecology, and understanding them can provide insights into the evolutionary history of plants. However, the study of moss traits and their relationship with their environment is far behind that of vascular plants. We sampled 303 assemblages of aquatic and semi‐aquatic (hygrophytic) mosses growing in semi‐natural springs distributed around the northeast of the Iberian Peninsula to study how moss traits vary depending on their evolutionary history, climate and water chemistry. To do so, we analysed 30 moss species and 17 traits using phylogenetic comparative methods and an extended RLQ analysis, accounting for spatial and phylogenetic information. We hypothesized that there is a sclerophylly continuum in mosses living across a gradient of high and low water conductivity springs that may mimic sclerophylly in vascular plants that live in stressful environments. Results indicated that life‐forms and, especially, morphological traits were well preserved phylogenetically and responsive to water chemistry and climate. That combined with spatial autocorrelation in environmental variables resulted in a clustered distribution of phylogenetically closely related mosses in space. Mosses living in springs with a warm and dry climate that discharge hard water mainly presented species with needle‐like leaves, were denser, and had lower water absorption capacity. The opposite was found in cold, humid and soft water springs. Synthesis. Our results suggest that climate and water chemistry are main determinants of traits of hygrophytic mosses and of species distributions. We found evidence of a potential sclerophylly continuum in moss traits, which we hypothesize may be mainly related to physical and physiological constraints produced by water chemistry. Our findings describe moss sclerophylly in a gradient of water conductivity similar to that found in vascular plants with water availability and temperature. Further experimental studies will be required to confirm the observations found in this study. A free Plain Language Summary can be found within the Supporting Information of this article.

Nutrients control reproductive traits of hygrophytic bryophytes

“…We collected 253 bryophyte samples from 35 aquatic and semi‐aquatic species (hygrophytic bryophytes [Dierssen, 2001], 29 mosses and six liverworts, Table S1) from 164 springs distributed across Catalonia (north‐eastern Iberian Peninsula, Figure S1) along a large gradient of hydrochemical and climatic conditions (Fernández‐Martínez, Berloso et al., 2019). Our study area has a Mediterranean climate, ranging from humid to sub‐humid, but with large differences in mean annual temperature (from 4.2 to 15.7°C) and mean annual precipitation (from 567.4 to 1,202.4 mm/year).…”

“…All springs surveyed continuously drained untreated water from aquifers, so the chemical features of the water were constant within a spring over time (Ehrlén et al, 2000; Fernández‐Martínez, Margalef et al., 2019). The bryophytes were in constant contact with water (e.g.…”

“…Sexual reproduction has been extensively investigated in vascular plants because of the strong repercussions that fruit or seed production have on humans (such as agriculture and food security) and ecosystems (for example, plant dispersal or animal population dynamics). The evolution of reproductive traits, such as the interannually variable reproduction of wild plants (Fernández‐Martínez, Berloso et al., 2019; Herrera et al., 1998) or the evolution of crop yield from wild to domesticated plants (Abbo et al., 2010; Preece et al., 2017), has also been the focus of multiple investigations. However, the study of the reproductive traits of bryophytes has received much less attention, even though a good understanding of how they work may help us better understand the evolutionary constraints of reproductive traits in plants.…”

“…Consequently, a relatively large set of studies have reported an important role of plant nutrient concentrations in determining the frequency and strength of the reproductive efforts of wild plants. Most of these studies have concluded that differences in the availabilities of N and P are responsible for differences in reproductive efforts amongst stems, individuals, populations, and species (Ehrlén et al, 2000; Fernández‐Martínez, Pearse et al., 2019; Fernández‐Martínez et al., 2017; Fujita et al., 2014; Han et al., 2013; Miyazaki et al., 2014) and that nutrient concentrations (Camarero et al., 2010; Sala et al., 2012) and growth (Sánchez‐Humanes et al., 2011; Vergotti et al., 2019) of vegetative tissues may decrease after reproduction. In algae, instead, the relationship between nutrient availability and reproduction seems to be a bit more complicated.…”

“…To fill in this gap, we here collected 253 samples from 35 aquatic and semi‐aquatic (hygrophytic) bryophyte species inhabiting springs to determine whether bryophyte nutrient concentrations were associated with their reproductive traits. Springs are important hotspots of biodiversity (Cantonati et al., 2012, 2020; Cantonati et al., 2006), especially in the Mediterranean and semi‐arid regions, because they behave like small islands in which water is continuously available (Bes et al., 2018; Fernández‐Martínez, Berloso et al., 2019), providing the ecological requirements of many taxa that would disappear if the springs would be disturbed, polluted or dried out (Fernández‐Martínez, Corbera et al., 2020; Heino et al., 2005). One of these groups is aquatic and semi‐aquatic bryophytes that, additionally, can act as engineering species (Cantonati et al., 2012) in those environments (e.g.…”