Perspectives in Plant Ecology Evolution and Systematics最新文献

Organisms can adapt to environmental heterogeneity through two mechanisms: (1) expression of population genetic variation or (2) phenotypic plasticity. In this study we investigated whether patterns of variation in both trait means and phenotypic plasticity along elevational and latitudinal clines in a North American endemic plant, Mimulus laciniatus, were consistent with local adaptation. We grew inbred lines of M. laciniatus from across the species’ range in two common gardens varying in day length to measure mean and plastic trait expression in several traits previously shown to be involved in adaptation to M. laciniatus’s rocky outcrop microhabitat: flowering time, size-related traits, and leaf shape. We tested for phenotypic plasticity and GxE, examined correlations between the mean phenotype and plasticity, and tested for a relationship between trait variation and population elevation and latitude. We did not find a strong correlation between mean and plastic trait expression at the individual genotype level suggesting that they operate under independent genetic controls. We identified multiple traits that show patterns consistent with local adaptation to elevation: critical photoperiod, flowering time, flower size, mean leaf lobing, and leaf lobing plasticity. These trends occur along multiple geographically independent altitudinal clines indicating that selection is a more likely cause of this pattern than gene flow among nearby populations with similar trait values. We also found that population variation in mean leaf lobing is associated with latitude. Our results indicate that both having more highly lobed leaves and greater leaf shape plasticity may be adaptive at high elevation within M. laciniatus. Our data strongly suggest that traits known to be under divergent selection between M. laciniatus and close relative Mimulus guttatus are also under locally varying selection within M. laciniatus.

The Capparis spinosa group is represented in the Mediterranean by a complex of taxa widespread in North Africa, the Middle East, and southern Europe. The taxonomy of this group used to be based on morphological characters with little work on the genetics of the group, and there is still much to be learned about its evolutionary history and diversification. We sampled 431 individuals of two subspecies and five varieties of C. spinosa and analysed them using highly informative EST-SSR markers to evaluate the population genetic diversity, structure and differentiation of the species in the Mediterranean. In addition, comparisons with the genetic profiles of C. spinosa subsp. cartilaginea, the putative ancestral taxon were made to investigate the phylogeographic history and possible gene flow across taxa. Integrated Bayesian approaches showed: i) a high divergence among C. spinosa subsp. spinosa var. canescens, C. spinosa subsp. spinosa var. aegyptia and the three varieties belonging to C. spinosa subsp. rupestris (var. rupestris, var. ovata and var. myrtifolia), with a clear separation between var. aegyptia and var. canescens which allows to consider var. aegyptia as a subspecies of C. spinosa; ii) a significant correlation between genetic divergence and geographic distance between the five varieties studied; iii) that the different varieties in the Mediterranean may have been derived from C. spinosa subsp. cartilaginea. Further genomic investigations are required to confirm our results. However, the findings presented allows us to suggest the genus Capparis can be considered a model for the study of the gene flow and differentiation in species occurring in a wide range of habitats.

Areas where range-restricted species are concentrated are of importance for conservation. However, most of the studies aim at identifying areas rich in endemics for conservation planning, while few studies aim at understanding the causal factors of endemic richness. Here, our goal is to identify the determinants of endemic richness within a centre of endemism, the Southwestern European Alps, by testing four non-mutually exclusive hypotheses that have been proposed to explain patterns of endemic richness. In particular, we examined to what extent temporal and spatial climatic stability and environmental heterogeneity are related to endemic richness. Almost all hypotheses partially support the observed patterns of plant endemics richness within the SW Alps. In general, most of the relationships between environmental variables and endemic richness are statistically significant. However, the highest effect in explaining endemic richness is found for climate change velocity and standard deviation of slope, two factors affecting the possibility of species to disperse. This is in line with the idea that endemics are strongly limited by dispersal and not only by climate. Our results suggest that in regions where the effects of past climate changes were less dramatic endemic richness results from the interaction of species dispersal with regional and specific historical factors.

Current distribution of C₃ and C₄ grasses is often explained by contrasting environmental conditions. Regions where C₃ and C₄ grasses coexist, as the Southeastern South America grasslands (SESA grasslands), provides an excellent opportunity to investigate the evolutionary imprints of grasses through clade distribution patterns. Here, we aimed to understand how ecological and evolutionary processes affect the phylogenetic diversity of grass communities along 666 sites located in a latitudinal gradient ranging from 26°S to 38°S in SESA grasslands (Argentina, Brazil, and Uruguay). We applied generalized linear models (GLM) to understand the role of the different environmental and historical drivers that shape the proportion of C₃ grasses distribution in SESA grasslands. The effect of latitude on phylogenetic beta-diversity patterns among the vegetation surveys was evaluated through principal coordinates of phylogenetic structure. Contribution of C₃ species increased southwards (R² = 0.40, P<0.001). C₃ species are more likely to occur in colder areas with higher historical temperature stability, reflecting lineages that have specialized and radiated in cold environments (GLM results: R² = 0.37, P<0.01). Climatically stable areas are the coldest, while unstable areas include warmer habitats, which enabled colonization by C₄ species. Regarding soil conditions, C₃ grasses are more likely to occur in more fertile soils and with low capacity to retain water (GLM results: pseudo-R² = 0.37, P<0.01). We found that phylogeny has an important role as a structuring agent of grass communities across our study region, indicating turnover of grass lineages along the latitudinal gradient. Grass species found at the northern portion of the gradient belong mostly to the clade which contain both C₄ and C₃ species. At the southern part of the gradient, communities are dominated by grasses belonging to a C₃-exclusive clade. The distribution of grass clades across the SESA grasslands is indicative of the environmental gradients found in this region between temperate and tropical zones, describing a climate space where disturbance driven feedbacks play a major role in maintaining open vegetation. Our results contribute to the understanding of ecological and evolutionary drivers of grass distribution in the region that up to now has been poorly described.

Herbivory is one of the key processes shaping life history traits linked to plant fitness and the leaf-cutting ants are amongst the most voracious and polyphagous herbivores of the Neotropics. They extensively harvest aboveground plant parts to grow their symbiotic fungus, including vegetative and reproductive tissues. Although leaf-cutting ant herbivory is expected to reduce plant reproductive success, the potentially different outputs of damage to vegetative and reproductive parts are still poorly known. This study investigates the influence of Atta opaciceps herbivory on the reproductive success of three plant species native to the Caatinga dry forest: Croton argyrophylloides (Euphorbiaceae), Cenostigma pyramidale, and Indigofera suffruticosa (Leguminosae). We selected 10 adult and active nests of A. opaciceps based on the presence of individuals of the three focal plant species in their vicinity. For each colony, we marked four individuals of each plant species (totaling 12 individuals per colony), which were then subjected to one of four herbivory treatments: (1) ant herbivory on both reproductive and vegetative parts, (2) manually simulated herbivory on the reproductive parts alone, (3) ant herbivory exclusively on vegetative parts, and (4) no herbivory. From January to April 2020, we monitored all 120 individuals, recording the number of inflorescences, flower buds, flowers, fruits, and the proportion of flowers maturing into fruits (fruit set, as a proxy of reproductive success). Results revealed variations in reproductive structure production and divergent responses to leaf-cutting ant herbivory among our focal species. In terms of inflorescence, flower bud production, and fruit set C. argyrophylloides showed reduced numbers when subjected to higher levels of total herbivory (reproductive and vegetative parts), but increased inflorescence and flower bud production when plants suffered only leaf damage. Cenostigma pyramidale individuals under partial herbivory displayed lower flower bud numbers than protected ones. In contrast, I. suffruticosa displayed conflicting results, with fully exposed plants producing more inflorescences than partially exposed counterparts and more flowers than leaf-damaged and protected individuals. Despite the varied effects on different plant parts across all three study species, the overall reproductive success (i.e. fruit set) of only one species (C. argyrophylloides) was significantly reduced by leaf-cutting ant herbivory. The resilience of the two other plant species to leaf-cutting ant pressure may be attributed to compensatory mechanisms, shedding light on the intricate interplay between herbivores and plants in the Caatinga dry forest. As leaf-cutting ants proliferate in response to anthropogenic disturbances, the patterns described in this study may become more pronounced, potentially affecting the organization of p