Effects of fragmentation and seawater submergence on photochemical efficiency and growth in the clonal invader Carpobrotus edulis

This is an Accepted Manuscript of an article published by Elsevier: "Roiloa, S., & Retuerto, R. (2016). Effects of fragmentation and seawater submergence on photochemical efficiency and growth in the clonal invader Carpobrotus edulis. Flora - Morphology, Distribution, Functional Ecology Of Plants, 225, 45-51", available online: https://doi.org/10.1016/j.flora.2016.10.002Clonal plants are frequently affected by process of disturbance as fragmentation. The capacity of these fragments to survive and grow after disturbance has important implications for the expansion of clonal plants, and could have special consequences for the colonization of new environments by invasive clonal species. Stolon internodes of clonal plants represent important reserve organs. These storage structures can play a crucial role in the survival and re-growth of clonal plants after an event of disturbance. In this study we simulated physical disturbance by fragmentation of clones of the stoloniferous invader Carpobrotus edulis into ramets with short and long stolon lengths, and a subsequent event of seawater submergence and de-submergence. Ramets with long stolons showed a significantly higher total biomass than ramets with short stolons, supporting the idea that stolon length is related with the amount of reserves stored and with the benefit reported in terms of growth. Our results showed that the benefit of having long stolons was also important for clonal fragments that suffered a process of seawater submergence. Our study suggests that the use of stolon as a source of resources can represent a suitable mechanism for colonization of coastal sand dunes by the aggressive invader C. edulisFinancial support for this study was provided by the Spanish Ministry of Economy and Competitiveness (projects Ref. CGL2013-44519-R, awarded to S.R.R. and Ref. CGL2013-48885-C2-2-R, awarded to R.R.). These projects were co-financed by the European Regional Development Fund (ERDF). This is a contribution from the Alien Species Network (Ref. R2014/036 – Xunta de Galicia, Autonomous Government of Galicia)S

A test of native plant adaptation more than one century after introduction of the invasive Carpobrotus edulis to the NW Iberian Peninsula

Background: Although the immediate consequences of biological invasions on ecosystems and conservation have been widely studied, the long-term effects remain unclear. Invaders can either cause the extinction of native species or become integrated in the new ecosystems, thus increasing the diversity of these ecosystems and the services that they provide. The final balance of invasions will depend on how the invaders and native plants co-evolve. For a better understanding of such co-evolution, case studies that consider the changes that occur in both invasive and native species long after the introduction of the invader are especially valuable. In this work, we studied the ecological consequences of the more than one century old invasion of NW Iberia by the African plant Carpobrotus edulis. We conducted a common garden experiment to compare the reciprocal effects of competition between Carpobrotus plants from the invaded area or from the native African range and two native Iberian plant species (Artemisia crithmifolia and Helichrysum picardii) from populations exposed or unexposed to the invader. Results: Exposure of H. picardii populations to C. edulis increased their capacity to repress the growth of Carpobrotus. The repression specifically affected the Carpobrotus from the invader populations, not those from the African native area. No effects of exposition were detected in the case of A. crithmifolia. C. edulis plants from the invader populations had higher growth than plants from the species' African area of origin. Conclusions: We found that adaptive responses of natives to invaders can occur in the long term, but we only found evidence for adaptive responses in one of the two species studied. This might be explained by known differences between the two species in the structure of genetic variance and gene flow between subpopulations. The overall changes observed in the invader Carpobrotus are consistent with adaptation after invasionThis research and publication costs were funded by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (ERDF) (grant Ref. CGL2013-48885-C2-2-R)S

Sexual dimorphism in response to stress

This article is part of a special issue entitled “Sexual dimorphism in response to stress” published at the journal Environmental and Experimental Botany 146Sexual dimorphism in secondary traits (differences between the sexes in characteristics others than the sexual organs) is widespread in plants (Geber and Dawson, 1999; Barrett and Hough 2013). Sex differences in ecological, morphological and physiological traits have been commonly attributed to the different costs of reproduction associated with the male and the female function (Reznick, 1985; Obeso, 2002) and are usually linked to trade-offs between allocation to reproduction and to other plant functions (e.g., to growth and/or defence). Such trade-offs are likely to be modified under more stressful conditions (Bazzaz and Grace, 1997). In fact, plants are continuously exposed to stressful biotic and abiotic environmental factors during all their life cycle, which usually occur simultaneously (Suzuki et al., 2014). Biotic factors include competitors, symbionts, parasites, pathogens, and herbivores. Abiotic factors include extreme temperatures, water, light and nutrient availability, heavy metal, CO2, or UV radiation. As sessile organisms, plants have developed a wide range of responses to cope with stress, ranging from escape to tolerance and avoidance (Lerner, 1999)S

Phylogeography of a widespread species: pre-glacial vicariance, refugia, occasional blocking straits and long-distance migrations

Phylogeographic studies give us the opportunity to reconstruct the historical migrations of species and link them with climatic and geographic variation. They are, therefore, a key tool to understanding the relationships among biology, geology and history. One of the most interesting biogeographical areas of the world is the Mediterranean region. However, in this area, the description of concordant phylogeographic patterns is quite scarce, which limits the understanding of evolutionary patterns related to climate. Species with one-dimensional distribution ranges, such as the strawberry tree ( Arbutus unedo ), are particularly useful to unravel these patterns. Here, we describe its phylogeographic structure and check for concordance with patterns seen in other Mediterranean plants: longitudinal/latitudinal clines of diversity, evidence for glacial refugia and the role of sea straits in dispersal. We also identify the most likely source for the disjunct Irish population. With this aim, we sequenced four chloroplast non-coding fragments of A. unedo from 23 populations covering its whole distribution. We determined the genetic diversity, population structure, haplotype genealogy and time to the most recent common ancestor. The genealogy revealed two clades that separated during the last 700 ky but before the last glacial maximum. One clade occupies Atlantic Iberia and North Africa, while the other occurs in the Western Mediterranean. The Eastern Mediterranean is inhabited by newer haplotypes derived from both clades, while the Irish population is closely related to Iberian demes. The straits of Sicily and Gibraltar partially restricted the gene flow. We concluded that a vicariance event during the Late Quaternary in the western end of the species' range followed by eastward migration seems a likely explanation for the observed phylogeographic pattern. The role of straits indicates an occasional communication between Europe and North Africa, suggesting that the latter was a novel refugia. The East–West genetic split in Iberia is consistent with the refugia-within-refugia model. Finally, the strawberry tree possibly reached Ireland from Iberia instead of throughout the maritime fringe of France as previously thoughtThis work was supported by the Spanish Ministry of Science and Innovation (research grant CGL2009-11356), the European Regional Development's Fund (ERDF) and also by the Spanish Ministry of Education (FPU fellowship AP-2009-0962 to X.S.)S

Population Structure of a Widespread Species under Balancing Selection: The Case of Arbutus unedo L.

Arbutus unedo L. is an evergreen shrub with a circum-Mediterranean distribution that also reaches the Eurosiberian region in northern Iberia, Atlantic France, and a disjunct population in southern Ireland. Due to the variety of climatic conditions across its distribution range, the populations of A. unedo were expected to display local adaptation. Conversely, common garden experiments revealed that diverse genotypes from a range of provenances produce similar phenotypes through adaptive plasticity, suggesting the action of stabilizing selection across its climatically heterogeneous range. Nonetheless, since a uniform response might also result from extensive gene flow, we have inferred the population structure of A. unedo and assessed whether its extended and largely one-dimensional range influences gene flow with the help of AFLP genotypes for 491 individuals from 19 populations covering the whole range of the species. As we had anticipated, gene flow is restricted in A. unedo, providing further support to the hypothesis that stabilizing selection is the most likely explanation for the homogeneous phenotypes along the range. The Euro-Siberian populations were not particularly isolated from the Mediterranean. Instead, there was a distinct genetic divide between the populations around the Mediterranean Sea and those sampled along Atlantic coasts from northern Africa up to Ireland. This genetic structure suggests the action of historic rather than biogeographic factors as it seems consistent with a scenario of independent glacial refugia in the Atlantic and Mediterranean portions of the range of A. unedo. Genetic exchange was likewise restricted within each set of populations. Nevertheless, isolation-by-distance (IBD) was stronger, and FST increased faster with distance, along the Atlantic, suggesting that gene flow might be larger among Mediterranean populations. Genetic diversity was significantly lower in NW Iberia and Ireland than in other populations whereas Ireland was more closely related to populations in NW Iberia than to a population in Atlantic France, suggesting a postglacial stepping-stone colonization of the Atlantic coast. Altogether, our results show that stabilizing selection is able to homogenize the phenotypic response even when population structure is strong, gene flow is constrained, and the phylogeographic past is complexThis research was supported by research grant CGL2009-11356 (Ministerio de Ciencia e Innovación) and FPU fellowship AP-2009-0962 (Ministerio de Educación). This research was also supported by the European Regional Development's Fund (ERDF)S

Domestication influences morphological and physiological responses to salinity in Brassica oleracea seedlings

Brassica oleracea cultivars include important vegetable and forage crops grown worldwide, whereas the wild counterpart occurs naturally on European sea cliffs. Domestication and selection processes have led to phenotypic and genetic divergence between domesticated plants and their wild ancestors that inhabit coastal areas and are exposed to saline conditions. Salinity is one of the most limiting factors for crop production. However, little is known about how salinity affects plants in relation to domestication of B. oleracea. The objective of this study was to determine the influence of domestication status (wild, landrace or cultivar) on the response of different B. oleracea crops to salinity, as measured by seed germination, plant growth, water content and mineral concentration parameters at the seedling stage. For this purpose, two independent pot experiments were conducted with six accessions of B. oleracea, including cabbage (group capitata) and kale (group acephala), in a growth chamber under controlled environmental conditions. In both taxonomic groups, differences in domestication status and salt stress significantly affected all major process such as germination, changes in dry matter, water relations and mineral uptake. In the acephala experiment, the domestication × salinity interaction significantly affected water content parameters and shoot Na+ allocation. At early stages of development, wild plants are more succulent than cultivated plants and have a higher capacity to maintain lower Na+ concentrations in their shoots in response to increasing levels of salinity. Different responses of domesticated and cultivated accessions in relation to these traits indicated a high level of natural variation in wild B. oleracea. Exclusion of Na+ from shoots and increasing succulence may enhance salt tolerance in B. oleracea exposed to extreme salinity in the long term. The wild germplasm can potentially be used to improve the salt tolerance of crops by the identification of useful genes and incorporation of these into salinity-sensitive cultivars.M.L. recognizes an Isidro Parga Pondal-I2C Program fellowship from the Xunta de Galicia. Md.Y.A. was supported by the EXPERTS_II (Erasmus Mundus) Interchange ProgramS

Epigenetic and phenotypic responses to experimental climate change of native and invasive Carpobrotus edulis

Despite the recent discoveries on how DNA methylation could help plants to adapt to changing environments, the relationship between epigenetics and climate change or invasion in new areas is still poorly known. Here, we investigated, through a field experiment, how the new expected climate scenarios for Southern Europe, i.e., increased temperature and decreased rainfall, might affect global DNA methylation in relation to phenotypic variation in individuals of clonal plant, Carpobrotus edulis, from its native (Southern African) and invaded (northwestern Iberian Peninsula) area. Our results showed that changes in temperature and rainfall induced phenotypic but not global DNA methylation differences among plants, and the climatic effects were similar for plants coming from the native or invaded areas. The individuals from the Iberian Peninsula showed higher levels of global methylation than their native counterparts from South Africa. We also observed differences between natives and invasive phenotypes in traits related to the pattern of biomass partitioning and to the strategies for water uptake and use and found an epigenetic contribution to phenotypic changes in some leaf traits, especially on the nitrogen isotopic composition. We conclude that the increased temperature and decreased rainfall projected for Southern Europe during the course of the twenty-first century may foster phenotypic changes in C. edulis, possibly endowing this species with a higher ability to successful cope the rapid environmental shifts. The epigenetic and phenotypic divergence that we observed between native and invasive plants suggests an intraspecific functional variation during the process of invasion. This result could indicate that phenotypic plasticity and global DNA methylation are related to the colonization of new habitats. Our findings reinforce the importance of epigenetic plasticity on rapid adaptation of invasive clonal plantsFunding for this study was provided by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (ERDF; grant Ref. CGL2013-48885-C2-2-R and Ref. CGL2017-87294-C3-1P awarded to RR) and by the Autonomous Government of Galicia (grant ref. I2CB awarded to MS)S

Biomonitorización de la calidad del aire

VI Reunión Nacional de Climatología. Asociación de Geógrafos Españoles. Santiago de Compostela, 14-16 de septiembre de 200

Functional responses to climate change may increase invasive potential of Carpobrotus edulis

Premise: Biological invasions and climate change are major threats to biodiversity. It is therefore important to anticipate how the climate changes projected for Southern Europe would affect the ecophysiological performance of the invasive South African plant, Carpobrotus edulis (ice plant or sour fig), and its capacity to undergo rapid adaptive evolution. Methods: We manipulated the climate conditions in a field plot located on the island of Sálvora (northwest of the Iberian Peninsula) to establish a full factorial experiment with C. edulis plants transplanted from four native (southern African) and four invasive (northwestern Iberian Peninsula) populations. Throughout 14 months we measured growth and functional traits of this species under two temperatures (control vs. increased), and two rainfall levels (control vs. reduced). Results: Temperature increased photochemical efficiency and relative growth rate of C. edulis. Rainfall modulated some of the effects of temperature on C and N isotopic composition, and pigment contents. Invasive populations showed lower root mass allocation and higher survival rates, as well as increased water use efficiency, lipid peroxidation, chlorophyll, and xanthophyll cycle pigment contents than native populations. Conclusions: The increased growth and physiological performances observed under our experimental conditions suggest that the expected climate changes would further promote the invasion of C. edulis. Differences between native and invasive genotypes in survival and functional traits revealed that populations have diverged during the process of invasion, what gives support to the invasiveness hypothesis. Our findings highlight the importance of analyzing intraspecific variability in functional responses to better predict how invasive species will respond to environmental changesThe authors are grateful to the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (ERDF) for funding the study (grants Ref. CGL2013-48885-C2-2-R and Ref. CGL2017-87294-C3-1-P, awarded to R.R.)S