TY - JOUR A1 - García-Camacho, Raúl A1 - Metz, Johannes A1 - Bilton, Mark C. A1 - Tielboerger, Katja T1 - Phylogenetic structure of annual plant communities along an aridity gradient BT - Interacting effects of habitat filtering and shifting plant-plant interactions JF - Israel Journal of Plant Sciences N2 - The phylogenetic structure of communities (PSC) reveals how evolutionary history affects community assembly processes. However, there are important knowledge gaps on PSC patterns for annual communities and there is a need for studies along environmental gradients in dry ecosystems where several processes shape PSC. Here, we investigated the PSC of annual plants along an aridity gradient in Israel, including eight years, two spatial scales, the effects of shrubs on understory, and the phylogenetic signal of important traits. Increasing drought stress led to overdispersed PSC at the drier end of the gradient, indicating that species were less related than expected by chance. This was supported at a smaller spatial scale, where within the drier sites, communities in open- more arid- habitats were more overdispersed than those under nurse shrubs. Interestingly, some key traits related to drought resistance were not conserved in the phylogeny. Together, our findings suggested that while habitat filtering selected for drought resistance strategies, these strategies evolved independently along multiple contrasting evolutionary lineages. Our comprehensive PSC study provides strong evidence for the interacting effects of habitat filtering and plant- plant interactions, particularly highlighting that the conservative evolution of traits should not be assumed in future interpretations of PSC patterns. KW - Annuals KW - aridity gradient KW - community assembly rules KW - community phylogenetics KW - stress-gradient hypothesis KW - trait phylogenetic conservatism Y1 - 2017 U6 - https://doi.org/10.1080/07929978.2017.1288477 SN - 0792-9978 SN - 2223-8980 VL - 64 IS - 1-2 SP - 122 EP - 134 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Lampei, Christian A1 - Metz, Johannes A1 - Tielboerger, Katja T1 - Clinal population divergence in an adaptive parental environmental effect that adjusts seed banking JF - New phytologist : international journal of plant science N2 - Bet-hedging via between-year seed dormancy is a costly strategy for plants in unpredictable environments. Theoretically, fitness costs can be reduced through a parental environmental effect when the environment is partly predictable. We tested whether populations from environments that differ in predictability diverged in parental effects on seed dormancy. Common garden-produced seeds of the two annual plant species Biscutella didyma and Bromus fasciculatus collected along an aridity gradient were grown under 12 irrigation treatments. Offspring germination was evaluated and related to environmental correlations between generations and their fitness consequences at the four study sites. One species exhibited strong seed dormancy that increased with unpredictability in seasonal precipitation. The parental effect on seed dormancy also increased proportionally with the environmental correlation between precipitation in the parental season and seedling density in the following season; this correlation increased from mesic to arid environments. Because fitness was negatively related to density, this parental effect may be adaptive. However, the lack of dormancy in the second species indicates that bet-hedging is not the only strategy for annual plants in arid environments. Our results provide the first evidence for clinal variation in the relative strength of parental effects along environmental gradients. KW - bet-hedging KW - clinal variation KW - environmental autocorrelation KW - maternal effect KW - parental effect KW - risk spreading KW - seed dormancy KW - transgenerational plasticity Y1 - 2017 U6 - https://doi.org/10.1111/nph.14436 SN - 0028-646X SN - 1469-8137 VL - 214 SP - 1230 EP - 1244 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Tomiolo, Sara A1 - Metz, Johannes A1 - Blackwood, Christopher B. A1 - Djendouci, Karin A1 - Henneberg, Lorenz A1 - Mueller, Caroline A1 - Tielboerger, Katja T1 - Short-term drought and long-term climate legacy affect production of chemical defenses among plant ecotypes JF - Environmental and Experimental Botany N2 - Long and short-term climatic variation affect the ability of plants to simultaneously cope with increasing abiotic stress and biotic interactions. Specifically, ecotypes adapted to different climatic conditions (i.e., long-term legacy) may have to adjust their allocation to chemical defenses against enemies under acute drought (i.e., short-term response). Although several studies have addressed drought effects on chemical defense production, little is known about their intraspecific variation along resource gradients. Studying intraspecific variation is important for understanding how different environments select for defense strategies and how these may be affected directly and indirectly by changing climatic conditions. We conducted greenhouse experiments with the annual Biscutella didyma (Brassicaceae) to test the effects of long-term climatic legacy versus short-term drought stress on the concentrations of defense compounds (glucosinolates). To this aim, four ecotypes originating from a steep aridity gradient were exposed to contrasting water treatments. Concentrations of chemical defenses were measured separately in leaves of young (8 weeks) and old (14 weeks) plants, respectively. For young plants, ecotypes from the wettest climate (long-term legacy) as well as plants receiving high water treatments (short-term response) were better defended. A marginally significant interaction suggested that wetter ecotypes experienced a larger shift in defense production across water treatments. Older plants contained much lower glucosinolate concentrations and showed no differences between ecotypes and water treatments. Our results indicate that younger plants invest more resources into chemical defenses, possibly due to higher vulnerability to tissue loss compared to older plants. We propose that the strong response of wet ecotypes to water availability may be explained by a less pronounced adaptation to drought. KW - Plant chemical defense KW - Glucosinolates KW - Climatic legacy KW - Short-term drought KW - Brassicaceae KW - Gradients Y1 - 2017 U6 - https://doi.org/10.1016/j.envexpbot.2017.07.009 SN - 0098-8472 SN - 1873-7307 VL - 141 SP - 124 EP - 131 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Metz, Johannes A1 - Tielboerger, Katja T1 - Spatial and temporal aridity gradients provide poor proxies for plant-plant interactions under climate change: a large-scale experiment JF - Functional ecology : an official journal of the British Ecological Society N2 - 1. Plant-plant interactions may critically modify the impact of climate change on plant communities. However, the magnitude and even direction of potential future interactions remains highly debated, especially for water-limited ecosystems. Predictions range from increasing facilitation to increasing competition with future aridification. 2. The different methodologies used for assessing plant-plant interactions under changing environmental conditions may affect the outcome but they are not equally represented in the literature. Mechanistic experimental manipulations are rare compared with correlative approaches that infer future patterns from current observations along spatial climatic gradients. 3. Here, we utilize a unique climatic gradient in combination with a large-scale, long-term experiment to test whether predictions about plant-plant interactions yield similar results when using experimental manipulations, spatial gradients or temporal variation. We assessed shrub-annual interactions in three different sites along a natural rainfall gradient (spatial) during 9 years of varying rainfall (temporal) and 8 years of dry and wet manipulations of ambient rainfall (experimental) that closely mimicked regional climate scenarios. 4. The results were fundamentally different among all three approaches. Experimental water manipulations hardly altered shrub effects on annual plant communities for the assessed fitness parameters biomass and survival. Along the spatial gradient, shrub effects shifted from clearly negative to mildly facilitative towards drier sites, whereas temporal variation showed the opposite trend: more negative shrub effects in drier years. 5. Based on our experimental approach, we conclude that shrub-annual interaction will remain similar under climate change. In contrast, the commonly applied space-for-time approach based on spatial gradients would have suggested increasing facilitative effects with climate change. We discuss potential mechanisms governing the differences among the three approaches. 6. Our study highlights the critical importance of long-term experimental manipulations for evaluating climate change impacts. Correlative approaches, for example along spatial or temporal gradients, may be misleading and overestimate the response of plant-plant interactions to climate change. KW - annual plant communities KW - climate manipulation KW - competition KW - facilitation KW - Mediterranean shrubland KW - nurse plant KW - rainfall gradient KW - Sarcopoterium spinosum KW - semi-arid KW - stress-gradient hypothesis Y1 - 2016 U6 - https://doi.org/10.1111/1365-2435.12599 SN - 0269-8463 SN - 1365-2435 VL - 30 SP - 20 EP - 29 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Bilton, Mark C. A1 - Metz, Johannes A1 - Tielboerger, Katja T1 - Climatic niche groups: A novel application of a common assumption predicting plant community response to climate change JF - Perspectives in plant ecology, evolution and systematics N2 - Defining species by their climatic niche is the simple and intuitive principle underlying Bioclimatic Envelope Model (BEM) predictions for climate change effects. However, these correlative models are often criticised for neglecting many ecological processes. Here, we apply the same niche principle to entire communities within a medium/long-term climate manipulation study, where ecological processes are inherently included. In a nine generation study in Israel, we manipulated rainfall (Drought -30%; Irrigation +30%; Control natural rainfall) at two sites which differ chiefly in rainfall quantity and variability. We analysed community responses to the manipulations by grouping species based on their climatic rainfall niche. These responses were compared to analyses based on single species, total densities, and commonly used taxonomic groupings. Climate Niche Groups yielded clear and consistent results: within communities, those species distributed in drier regions performed relatively better in the drought treatment, and those from wetter climates performed better when irrigated. In contrast, analyses based on other principles revealed little insight into community dynamics. Notably, most relationships were weaker at the drier, more variable site, suggesting that enhanced adaptation to variability may buffer climate change impacts. We provide robust experimental evidence that using climatic niches commonly applied in BEMs is a valid approach for eliciting community changes in response to climate change. However, we also argue that additional empirical information needs to be gathered using experiments in situ to correctly assess community vulnerability. Climatic Niche Groups used in this way, may therefore provide a powerful tool and directional testing framework to generalise and compare climate change impacts across habitats. (C) 2016 The Authors. Published by Elsevier GmbH. KW - Annual plant communities KW - Bioclimatic envelope modelling KW - Climate change manipulations KW - Experimental evidence KW - Plant functional groups KW - Rainfall niche Y1 - 2016 U6 - https://doi.org/10.1016/j.ppees.2016.02.006 SN - 1433-8319 VL - 19 SP - 61 EP - 69 PB - Elsevier CY - Jena ER -