The spatial configuration of biotic interactions shapes coexistence-area relationships in an annual plant community

The increase of species richness with area is a universal phenomenon on Earth. However, this observation contrasts with our poor understanding of how these species-area relationships (SARs) emerge from the collective effects of area, spatial heterogeneity, and local interactions. By combining a structuralist approach with five years of empirical observations in a highly-diverse Mediterranean grassland, we show that spatial heterogeneity plays a little role in the accumulation of species richness with area in our system. Instead, as we increase the sampled area more species combinations are realized, and they coexist mainly due to direct pairwise interactions rather than by changes in single-species dominance or by indirect interactions. We also identify a small set of transient species with small population sizes that are consistently found across spatial scales. These findings empirically support the importance of the architecture of species interactions together with stochastic events for driving coexistence- and species-area relationships. Local patterns of species coexistence across scales could determine the shape of species-area relationships. Here the authors apply a structuralist approach to empirical data on annual plant communities to assess how species interactions shape coexistence- and species-area relationships

Does deterministic coexistence theory matter in a finite world?

Contemporary studies of species coexistence are underpinned by deterministic models that assume that competing species have continuous (i.e., noninteger) densities, live in infinitely large landscapes, and coexist over infinite time horizons. By contrast, in nature, species are composed of discrete individuals subject to demographic stochasticity and occur in habitats of finite size where extinctions occur in finite time. One consequence of these discrepancies is that metrics of species' coexistence derived from deterministic theory may be unreliable predictors of the duration of species coexistence in nature. These coexistence metrics include invasion growth rates and niche and fitness differences, which are now commonly applied in theoretical and empirical studies of species coexistence. In this study, we tested the efficacy of deterministic coexistence metrics on the duration of species coexistence in a finite world. We introduce new theoretical and computational methods to estimate coexistence times in stochastic counterparts of classic deterministic models of competition. Importantly, we parameterized this model using experimental field data for 90 pairwise combinations of 18 species of annual plants, allowing us to derive biologically informed estimates of coexistence times for a natural system. Strikingly, we found that for species expected to deterministically coexist, community sizes containing only 10 individuals had predicted coexistence times of more than 1000 years. We also found that invasion growth rates explained 60% of the variation in intrinsic coexistence times, reinforcing their general usefulness in studies of coexistence. However, only by integrating information on both invasion growth rates and species' equilibrium population sizes could most (>99%) of the variation in species coexistence times be explained. This integration was achieved with demographically uncoupled single-species models solely determined by the invasion growth rates and equilibrium population sizes. Moreover, because of a complex relationship between niche overlap/fitness differences and equilibrium population sizes, increasing niche overlap and increasing fitness differences did not always result in decreasing coexistence times, as deterministic theory would predict. Nevertheless, our results tend to support the informed use of deterministic theory for understanding the duration of species' coexistence while highlighting the need to incorporate information on species' equilibrium population sizes in addition to invasion growth rates

Pathways to global-change effects on biodiversity: new opportunities for dynamically forecasting demography and species interactions

In structured populations, persistence under environmental change may be particularly threatened when abiotic factors simultaneously negatively affect survival and reproduction of several life cycle stages, as opposed to a single stage. Such effects can then be exacerbated when species interactions generate reciprocal feedbacks between the demographic rates of the different species. Despite the importance of such demographic feedbacks, forecasts that account for them are limited as individual-based data on interacting species are perceived to be essential for such mechanistic forecasting-but are rarely available. Here, we first review the current shortcomings in assessing demographic feedbacks in population and community dynamics. We then present an overview of advances in statistical tools that provide an opportunity to leverage population-level data on abundances of multiple species to infer stage-specific demography. Lastly, we showcase a state-of-the-art Bayesian method to infer and project stage-specific survival and reproduction for several interacting species in a Mediterranean shrub community. This case study shows that climate change threatens populations most strongly by changing the interaction effects of conspecific and heterospecific neighbours on both juvenile and adult survival. Thus, the repurposing of multi-species abundance data for mechanistic forecasting can substantially improve our understanding of emerging threats on biodiversity.12 página

Fine scale prediction of ecological community composition using a two-step sequential Machine Learning ensemble

Prediction is one of the last frontiers in ecology. Indeed, predicting fine-scale species composition in natural systems is a complex challenge as multiple abiotic and biotic processes operate simultaneously to determine local species abundances. On the one hand, species intrinsic performance and their tolerance limits to different abiotic pressures modulate species abundances. On the other hand there is growing recognition that species interactions play an equally important role in limiting or promoting such abundances within ecological communities. Here, we present a joint effort between ecologists and data scientists to use data-driven models to predict species abundances using reasonably easy to obtain data. We propose a sequential data-driven modeling approach that in a first step predicts the potential species abundances based on abiotic variables, and in a second step uses these predictions to model the realized abundances once accounting for species competition. Using a curated data set over five years we predict fine-scale species abundances in a highly diverse annual plant community. Our models show a remarkable spatial predictive accuracy using only easy-to-measure variables in the field, yet such predictive power is lost when temporal dynamics are taken into account. This result suggests that predicting future abundances requires longer time series analysis to capture enough variability. In addition, we show that these data-driven models can also suggest how to improve mechanistic models by adding missing variables that affect species performance such as particular soil conditions (e.g. carbonate availability in our case). Robust models for predicting fine-scale species composition informed by the mechanistic understanding of the underlying abiotic and biotic processes can be a pivotal tool for conservation, especially given the human-induced rapid environmental changes we are experiencing. This objective can be achieved by promoting the knowledge gained with classic modelling approaches in ecology and recently developed data-driven models. Author summary Prediction is challenging but recently developed Machine Learning techniques allow to dramatically improve prediction accuracy in several domains. However, these tools are often of little application in ecology due to the hardship of gathering information on the needed explanatory variables, which often comprise not only physical variables such as temperature or soil nutrients, but also information about the complex network of species interactions that modulate species abundances. Here we present a two-step sequential modelling framework that overcomes these constraints. We first infer potential species abundances by training models just with easily obtained abiotic variables and then use this outcome to fine-tune the prediction of the realized species abundances when taking into account the rest of the predicted species in the community. Overall, our results show a promising way forward for fine scale prediction in ecology.O.G. acknowledges support provided by the Ministerio de Ciencia, Innovacion y Universidades (RYC-2017-23666). O.G. and I.B. acknowledge financial support provided by the Secretaria de Estado de Investigacion, Desarrollo e Innovacion (CGL2017-92436-EXP, SIMPLEX and RTI2018-098888-A-I00, MeDiNaS). J.G. acknowledges financial support provided by the Ministerio de Ciencia, Innovacion y Universidades (PGC2018-093854-B-I00). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

The morphometric acclimation to depth explains the long-term resilience of the seagrass Cymodocea nodosa in a shallow tidal lagoon

Cadiz Bay is a shallow mesotidal lagoon with extensive populations of the seagrass Cymodocea nodosa at intertidal and shallow subtidal elevations. This work aims to understand the mechanisms behind the resilience of this species to gradual sea level rise by studying its acclimation capacity to depth along the shallow littoral, and therefore, to gradual variations in the light environment. To address this objective, these populations have been monitored seasonally over a 10 year period, representing the longest seasonal database available in the literature for this species. The monitoring included populations at 0.4, -0.08 and -0.5 m LAT. The results show that C. nodosa has a strong seasonality for demographic and shoot dynamic properties - with longer shoots and larger growth in summer (high temperature) than in winter (low temperature), but also some losses. Moreover, shoots have different leaf morphometry depending on depth, with small and dense shoots in the intertidal areas (0.4 m) and sparse large shoots in the subtidal ones (-0.08 and 0.5 m). These differences in morphometry and shoot dynamic properties, combined with the differences in shoot density, explain the lack of differences in meadow production balance (i.e. meadow growth - meadow losses) between the intertidal (0.4 m) and the deepest population (-0.5 m), supporting the long term resilience of Cymodocea nodosa in Cadiz Bay. This study contributes to the understanding of the mechanisms behind seagrass stability and resilience, which is particularly important towards predicting the effects of climate change on these key coastal ecosystems, and also highlights the value of continuous long-term monitoring efforts to evaluate seagrass trajectories

Rasgos funcionales y plasticidad fenotípica de plantas exóticas invasoras

Premio Extraordinario de Doctorado 2012Esta Tesis Doctoral se centra en el estudio de los rasgos funcionales y la plasticidad fenotípica que se asocian con el potencial invasor de las plantas exóticas y sus impactos sobre los ecosistemas mediterráneos. Los objetivos principales fueron: i) buscar diferencias de fenotipo entre especies invasoras y nativas para un amplio grupo de rasgos morfológicos y fisiológicos, ii) determinar si una elevada plasticidad fenotípica se asocia con el potencial invasor de las plantas exóticas, iii) establecer si los rasgos foliares asociados al potencial invasor de las plantas exóticas influyen posteriormente en el ciclo de nutrientes de los ecosistemas, y iv) explicar si las diferencias en el periodo de floración entre especies invasoras y nativas es un rasgo que confiere invasividad. Para ello, se estudió la respuesta de 31 rasgos morfológicos y fisiológicos en 20 pares de especies invasoras y nativas a dos amplios gradientes de luz y nutrientes (capítulo 2). Para el objetivo 3, se midieron los rasgos iniciales de la hojarasca de 19 pares de especies invasoras-nativas, se calcularon las tasas de descomposición y se determinó la importancia relativa de cada rasgo inicial sobre el proceso de descomposición (capítulo 3). Por último, se comparó la fenología de floración de 227 pares de especies invasoras y nativas en tres ecosistemas de tipo mediterráneo a nivel mundial (capítulo 4 y 5). Los resultados de la Tesis Doctoral muestran que las especies invasoras son más eficientes en el uso de la luz y el nitrógeno en comparación con las especies nativas, lo que resulta en una mayor eficacia biológica cuando se someten experimentalmente a gradientes de luz y nutrientes. Sin embargo poseen menor eficiencia en el uso del agua lo que les restringe a invadir mayoritariamente zonas donde el aporte hídrico es mayor y la sequía estival está minimizada. Contrario a lo que la teoría predice, las especies invasoras mostraron la misma plasticidad y en ocasiones incluso menor que las nativas. Pero al tener un fenotipo más competitivo la ganancia de eficacia biológica por unidad de plasticidad fue sistemáticamente mayor, con lo cual una mayor eficiencia de la plasticidad parece ser un rasgo asociado con el potencial invasor a las especies exóticas. La hojarasca de las especies invasoras mostró un mayor contenido de lignina que las nativas. El alto contenido en lignina en la hojarasca de las especies invasoras la hizo más dependiente del nitrógeno y el fósforo para su descomposición. Al ser la lignina difícil de degradar, la hojarasca de las especies invasoras se descompuso más lentamente que en las especies nativas, lo que sugiere que en un ecosistema invadido el ciclo de nutrientes se verá ralentizado por la presencia de las especies invasoras. La floración tardía de las especies invasoras con respecto a las nativas encontrada en los ecosistemas mediterráneos españoles no es una tendencia generalizada en otros ecosistemas mediterráneos como la Región Sudafricana de El Cabo y California donde las especies invasoras florecen antes y al mismo tiempo que las nativas respectivamente. Por tanto, un periodo de floración diferente entre especies invasoras y nativas no está asociado con la invasividad. Sin embargo, esta floración tardía sí condiciona el tipo de hábitat invadido y la forma de crecimiento de las especies invasoras en los ecosistemas mediterráneos españoles. En este sentido, al florecer en verano las especies que sobreviven son principalmente herbáceas ligadas a medios perturbados donde la sequía estival está minimizada

Rasgos funcionales y plasticidad fenotípica de plantas exóticas invasoras

Premio Extraordinario de Doctorado 2012Esta Tesis Doctoral se centra en el estudio de los rasgos funcionales y la plasticidad fenotípica que se asocian con el potencial invasor de las plantas exóticas y sus impactos sobre los ecosistemas mediterráneos. Los objetivos principales fueron: i) buscar diferencias de fenotipo entre especies invasoras y nativas para un amplio grupo de rasgos morfológicos y fisiológicos, ii) determinar si una elevada plasticidad fenotípica se asocia con el potencial invasor de las plantas exóticas, iii) establecer si los rasgos foliares asociados al potencial invasor de las plantas exóticas influyen posteriormente en el ciclo de nutrientes de los ecosistemas, y iv) explicar si las diferencias en el periodo de floración entre especies invasoras y nativas es un rasgo que confiere invasividad. Para ello, se estudió la respuesta de 31 rasgos morfológicos y fisiológicos en 20 pares de especies invasoras y nativas a dos amplios gradientes de luz y nutrientes (capítulo 2). Para el objetivo 3, se midieron los rasgos iniciales de la hojarasca de 19 pares de especies invasoras-nativas, se calcularon las tasas de descomposición y se determinó la importancia relativa de cada rasgo inicial sobre el proceso de descomposición (capítulo 3). Por último, se comparó la fenología de floración de 227 pares de especies invasoras y nativas en tres ecosistemas de tipo mediterráneo a nivel mundial (capítulo 4 y 5). Los resultados de la Tesis Doctoral muestran que las especies invasoras son más eficientes en el uso de la luz y el nitrógeno en comparación con las especies nativas, lo que resulta en una mayor eficacia biológica cuando se someten experimentalmente a gradientes de luz y nutrientes. Sin embargo poseen menor eficiencia en el uso del agua lo que les restringe a invadir mayoritariamente zonas donde el aporte hídrico es mayor y la sequía estival está minimizada. Contrario a lo que la teoría predice, las especies invasoras mostraron la misma plasticidad y en ocasiones incluso menor que las nativas. Pero al tener un fenotipo más competitivo la ganancia de eficacia biológica por unidad de plasticidad fue sistemáticamente mayor, con lo cual una mayor eficiencia de la plasticidad parece ser un rasgo asociado con el potencial invasor a las especies exóticas. La hojarasca de las especies invasoras mostró un mayor contenido de lignina que las nativas. El alto contenido en lignina en la hojarasca de las especies invasoras la hizo más dependiente del nitrógeno y el fósforo para su descomposición. Al ser la lignina difícil de degradar, la hojarasca de las especies invasoras se descompuso más lentamente que en las especies nativas, lo que sugiere que en un ecosistema invadido el ciclo de nutrientes se verá ralentizado por la presencia de las especies invasoras. La floración tardía de las especies invasoras con respecto a las nativas encontrada en los ecosistemas mediterráneos españoles no es una tendencia generalizada en otros ecosistemas mediterráneos como la Región Sudafricana de El Cabo y California donde las especies invasoras florecen antes y al mismo tiempo que las nativas respectivamente. Por tanto, un periodo de floración diferente entre especies invasoras y nativas no está asociado con la invasividad. Sin embargo, esta floración tardía sí condiciona el tipo de hábitat invadido y la forma de crecimiento de las especies invasoras en los ecosistemas mediterráneos españoles. En este sentido, al florecer en verano las especies que sobreviven son principalmente herbáceas ligadas a medios perturbados donde la sequía estival está minimizada

Dataset of Invasion risks and social interest of non-native woody plants in urban parks of Spain

Full datasets for the research entitled "Invasion risks and social interest of non-native woody plants in urban parks of Spain

Dataset of Proportion of non-native plants in urban parks correlates with climate, socioeconomic factors and plant traits

Full datasets for the research entitled 'Proportion of non-native plants in urban parks correlates with climate, socioeconomic factors and plant traits'