Biology subjects

Ramos-Jiliberto, R.

Publications and source records attributed to Ramos-Jiliberto, R..

6 recordsLinked to original sources

bioRxiv2026

The interaction of dispersal, species sorting, and priority effects, explains a unimodal response of β-diversity to immigration rates

A dominant perspective in metacommunity theory is that dispersal consistently homogenizes species composition across local communities. However, recent studies have reported a direct relationship between dispersal rate and {beta}-diversity, which has been attributed to the influence of priority effects and species sorting. The underlying mechanisms by which dispersal can either increase or decrease {beta}-diversity remain unclear, hindering our understanding of metacommunity assembly and the processes driving biodiversity patterns across time and space. We theoretically evaluated how purely random priority effects, priority effects conditioned by species dispersal abilities, and species sorting shape the {beta}-diversity-dispersal relationship in metacommunities open to exogenous dispersal (i.e., immigration) from a regional species pool. Our results show that the three evaluated processes foster community differentiation at intermediate exogenous dispersal rates when dispersal between communities (i.e. endogenous dispersal) is taking place. Additionally, the interaction between endogenous and exogenous dispersal homogenizes communities at low and high exogenous dispersal rates, determining a unimodal response of {beta}-diversity to increasing exogenous dispersal rates. Our findings contribute to a deeper mechanistic understanding of metacommunity assembly and offer a coherent explanation for previously observed empirical discrepancies, thereby challenging the traditional view of dispersal as a purely homogenizing process.

ecology↗

bioRxiv2020

Core-periphery structure in mutualistic networks: an epitaph for nestedness?

The calculation of nestedness has become a routine analysis in the study of ecological networks, as it is commonly associated with community resilience, robustness and species persistence. While meaningful in species distributional patterns, for an interaction matrix to be nested, specialist species must interact with ordered subsets of subsequently more generalized species -- not just with a lower number of species. However, after reviewing 419 papers on mutualistic networks published since nestedness was introduced for the study of species interactions in 2003, we have found that only two theoretical studies considered explicitly ordered subsets. Instead, most studies interpret nestedness as a core of densely connected generalist species, surrounded by a periphery of specialist species attached to this core -- a so-called core-periphery structure. Such a topological feature is generally perceived as a core-periphery structure in network science. Here, we argue that the concept of core-periphery may be more relevant for studies on mutualistic networks than the concept of nestedness, as ecologists are usually not interested in exploring in detail the ordered subsets that characterize nestedness but instead use nestedness to describe a topology with a core of densely linked generalist species surrounded by a sparsely linked periphery of specialists. To illustrate our arguments and the quantification of core-periphery structures, we calculate core-periphery and nestedness in a large publicly available dataset of mutualistic networks. We also describe the calculation of core-periphery structures, its relationship with nestedness, and provide the code inside the R package econetwork for its calculation in mutualistic networks. We hope that our review will help ecologists to move beyond nestedness towards a more explicit representation of the structure of ecological networks.

ecology↗

bioRxiv2020

Phenological shifts drive biodiversity loss in plant--pollinator networks

Plant-pollinator interactions are key for ecosystem maintenance and world crop production, and their occurrence depends on the synchronization of life-cycle events among interacting species. Phenological shifts observed for plant and pollinator species increase the risk of phenological mismatches, threatening community stability. However, the magnitudes and directions of phenological shifts present a high variability, both among communities and among species of the same community. Community-wide consequences of these different responses have not been explored. Additionally, variability in phenological and topological traits of species can affect their persistence probability under phenological changes. We explored the consequences of several scenarios of plant-pollinator phenological mismatches for community stability. We also assessed whether species attributes can predict species persistence under phenological mismatch. To this end, we used a dynamic model for plant-pollinator networks. The model incorporates active and latent life-cycle states of species and phenological dynamics regulating life-cycle transitions. Interaction structure and species phenologies were extracted from eight empirical plant-pollinator networks sampled at three locations during different periods. We found that for all networks and all scenarios, species persistence decreased with increasing magnitude of the phenological shift, for both advancements and delays in flowering phenologies. Changes in persistence depended on the scenario and the network being tested. However, all networks exhibited the lowest species persistence when the mean of the expected shift was equivalent to its standard deviation and this shift was greater than two weeks. Conversely, the highest species persistences occurred when earlier-flowering plants exhibited stronger shifts. Phenophase duration was the most important attribute as a driver of plant persistence. For pollinator persistence, species degree was the most important attribute, followed by phenophase duration. Our findings highlight the importance of phenologies on the stability and robustness of mutualistic networks. Author summaryPlant-pollinator interactions involve a great number of species and are essential for the functioning of natural and agricultural systems. These interactions are facing a great number of threats. In both plants and pollinators, life-cycle events including flowering and adult emergence are triggered by environmental cues such as temperature and snowmelt. Climate change has the potential to alter the timing of these events. These phenological shifts generate mismatches in the timing of interacting species. Thus, plants and their pollinators may not match in time and/or space, leaving flowers unpollinated and disrupting pollinator feeding. Given that natural communities are composed of multiple species interacting in complex ways, experimentally assessing the effects of this kind of perturbation is difficult. To tackle this challenge, we simulated different scenarios of phenological shifts for several empirical communities. Our results indicate that strong shifts in the timing of life-cycle events may represent a greater risk of community collapse. Likewise, plants with short blooming periods and pollinators with short activity periods or high specialization face a greater risk of extinction.

ecology↗

bioRxiv2019

Geographical origin determines responses to salinity of Mediterranean caddisflies

Many freshwater ecosystems worldwide, and particularly Mediterranean ones, show increasing levels of salinity. This changes in water conditions could affect abundance and distribution of inhabiting species as well as the provision of ecosystem services. In this study we conduct laboratory experiments using the macroinvertebrate Smicridea annulicornis as a model organism. Our factorial experiments were designed to evaluate the effects of geographical origin on organisms and salinity levels on survival and behavioral responses of caddisflies. The experimental organisms were captured from rivers belonging to three hydrological basins along a 450 Km latitudinal gradient in the Mediterranean region of Chile. Animals were exposed to three conductivity levels, from 180 to 1400 S/cm, close to the historical averages of the source rivers. We measured the behavioral responses to experimental stimulii and the survival time. Our results showed that geography origin shaped the behavioral and survival responses to salinity. In particular, survival and activity decreased more strongly with increasing salinity in organisms coming from more dilute waters. This suggests local adaptation to be determinant for salinity responses in this species of benthic invertebrate. In the current scenario of fast temporal and spatial changes in water levels and salt concentration, the conservation of geographic intra-specific variation of aquatic species is crucial for lowering the risk of salinity-driven biodiversity loss.

ecology↗

bioRxiv2019

Temporal switching of species roles in a plant-pollinator network

Mutualistic networks are highly dynamic, characterized by high temporal turnover of species and interactions. Yet, we have a limited understanding of how the internal structure of these networks and the roles species play in them vary through time. We used six years of observation data and a novel statistical method (dynamic stochastic block models) to assess how network structure and species roles change across time in a quantitative plant-pollinator network from a dryland ecosystem in Argentina. Our analyses revealed a core-periphery structure persistent through seasons and years. Yet, species roles as core or peripheral were highly dynamic: virtually all species that played a core role in some seasons were also peripheral in other seasons, while many other species remained always peripheral. Our results illuminate our understanding of the dynamics of ecological networks and have important implications for ecosystem management and conservation.

ecology↗

bioRxiv2018

The diversity of interaction types drives the functioning of ecological communities

Ecological communities are undeniably diverse, both in terms of the species that compose them as well as the type of interactions that link species to each other. Despite this long-recognition of the coexistence of multiple interaction types in nature, little is known about the consequences of this diversity for community functioning. In the ongoing context of global change and increasing species extinction rates, it seems crucial to improve our understanding of the drivers of the relationship between species diversity and ecosystem functioning.\n\nHere, using a multispecies dynamical model of ecological communities including various interaction types (e.g. competition for space, predator interference, recruitment facilitation), we studied the role of the presence and the intensity of these interactions for species diversity, community functioning (biomass and production) and the relationship between diversity and functioning.\n\nTaken jointly, the diverse interactions have significant effects on species diversity, whose amplitude and sign depend on the type of interactions involved and their relative abundance. They however consistently increase the slope of the relationship between diversity and functioning, suggesting that species losses might have stronger effects on community functioning than expected when ignoring the diversity of interaction types and focusing on feeding interactions only.

ecology↗