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Estay S.A.,Austral University of Chile | Lima M.,Linc Global | Bozinovic F.,Linc Global
Oikos | Year: 2014

Despite the amount of research on the consequences of global warming on ecological systems, most studies examine the impact of increases in average temperature. However, there are few studies concerning the role of thermal variability on ecological processes. Based on insect thermal and population ecology, we propose a theoretical framework for organizing the study of the role that thermal mean and variability plays in individual performance, and how it may affect population dynamics. Starting with three predictions of global warming scenarios, we develop null models of the expected changes in individual physiological performance and population dynamics. Ecological consequences in each scenario may range from simple changes in performance to drastic changes in population fluctuations and geographic ranges. In particular, our null models show that potential changes in the intrinsic population growth rate (Rm) will depend on the interaction of mean temperature and thermal variability, and that the net effect of the interaction could be synergistic or antagonistic. To evaluate these null models, we fit performance curves to compiled data from the literature on measurements of Rm at several constant and fluctuating temperatures. The fitted models showed that several of the qualitative characteristics predicted by the null model may be found in the fitted curves. We expect that this framework will be useful as a guide to study the influence of thermal changes on the dynamics of natural populations. Synthesis Despite the common assertion that global warming impacts depend on not only the mean temperatures but also on thermal variability, theoretical approaches to explain how the interaction of thermal mean and variability determines fitness are lacking. Here we propose a framework for studying the role of thermal mean and variability on individual performance and population dynamics. We developed null models that show how changes in the intrinsic population growth rate (Rm) will depend on the interaction of mean temperature and thermal variability, and that the net effect could be synergistic or antagonistic. We expect that this framework will be useful to study the influence of thermal changes on natural populations. © 2013 The Authors.


Godoy O.,Linc Global | Godoy O.,University of Alcalá | Valladares F.,Linc Global | Valladares F.,Rey Juan Carlos University | Castro-Diez P.,University of Alcalá
Functional Ecology | Year: 2011

1.Plastic responses to spatiotemporal environmental variation strongly influence species distribution, with widespread species expected to have high phenotypic plasticity. Theoretically, high phenotypic plasticity has been linked to plant invasiveness because it facilitates colonization and rapid spreading over large and environmentally heterogeneous new areas. 2.To determine the importance of phenotypic plasticity for plant invasiveness, we compare well-known exotic invasive species with widespread native congeners. First, we characterized the phenotype of 20 invasive-native ecologically and phylogenetically related pairs from the Mediterranean region by measuring 20 different traits involved in resource acquisition, plant competition ability and stress tolerance. Second, we estimated their plasticity across nutrient and light gradients. 3.On average, invasive species had greater capacity for carbon gain and enhanced performance over a range of limiting to saturating resource availabilities than natives. However, both groups responded to environmental variations with high albeit similar levels of trait plasticity. Therefore, contrary to the theory, the extent of phenotypic plasticity was not significantly higher for invasive plants. 4.We argue that the combination of studying mean values of a trait with its plasticity can render insightful conclusions on functional comparisons of species such as those exploring the performance of species coexisting in heterogeneous and changing environments. © 2011 The Authors. Functional Ecology © 2011 British Ecological Society.


Godoy O.,Linc Global | Godoy O.,University of Alcalá | Godoy O.,University of California at Santa Barbara | Valladares F.,Linc Global | And 2 more authors.
New Phytologist | Year: 2012

Functional traits, their plasticity and their integration in a phenotype have profound impacts on plant performance. We developed structural equation models (SEMs) to evaluate their relative contribution to promote invasiveness in plants along resource gradients. We compared 20 invasive-native phylogenetically and ecologically related pairs. SEMs included one morphological (root-to-shoot ratio (R/S)) and one physiological (photosynthesis nitrogen-use efficiency (PNUE)) trait, their plasticities in response to nutrient and light variation, and phenotypic integration among 31 traits. Additionally, these components were related to two fitness estimators, biomass and survival. The relative contributions of traits, plasticity and integration were similar in invasive and native species. Trait means were more important than plasticity and integration for fitness. Invasive species showed higher fitness than natives because: they had lower R/S and higher PNUE values across gradients; their higher PNUE plasticity positively influenced biomass and thus survival; and they offset more the cases where plasticity and integration had a negative direct effect on fitness. Our results suggest that invasiveness is promoted by higher values in the fitness hierarchy - trait means are more important than trait plasticity, and plasticity is similar to integration - rather than by a specific combination of the three components of the functional strategy. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.


Nunez-Villegas M.,University of Chile | Bozinovic F.,Linc Global | Sabat P.,University of Chile
Journal of Experimental Biology | Year: 2014

Mammals exposed to low temperatures increase their metabolic rate to maintain constant body temperature and thus compensate for heat loss. This high and costly energetic demand can be mitigated through thermoregulatory behavior such as social grouping or huddling, which helps to decrease metabolic rate as function of the numbers of individuals grouped. Sustained low temperatures in endothermic animals produce changes over time in rates of energy expenditure, by means of phenotypic plasticity. However, the putative modulating effect that huddling exerts on the flexibility of the basal metabolic rate (BMR) due to thermal acclimation remains unknown. We determined BMR values in Octodon degus, an endemic Chilean rodent, after being acclimated to either 15 or 30°C during 60 days, both alone and in groups of three and five individuals. At 15°C, BMR of huddling individuals was 40% lower than that of animals housed alone. Moreover, infrared thermography revealed a significant increase in local surface temperatures in huddled animals. Furthermore, individual thermal conductance was lower in individuals acclimated to 15°C than to 30°C, but no differences were observed between single and grouped animals. Our results indicate that huddling prevents an increase in BMR when animals are acclimated to cold conditions and that this effect is proportional to the number of animals grouped. © 2014. Published by The Company of Biologists Ltd.


Albrecht M.,Linc Global | Albrecht M.,Institute for Sustainability science | Padron B.,Linc Global | Bartomeus I.,CSIC - Doñana Biological Station | Traveset A.,Linc Global
Proceedings of the Royal Society B: Biological Sciences | Year: 2014

Compartmentalization-the organization of ecological interaction networks into subsets of species that do not interact with other subsets (true compartments) or interact more frequently among themselves than with other species (modules)-has been identified as a key property for the functioning, stability and evolution of ecological communities. Invasions by entomophilous invasive plants may profoundly alter the way interaction networks are compartmentalized. We analysed a comprehensive dataset of 40 paired plant-pollinator networks (invaded versus uninvaded) to test this hypothesis. We show that invasive plants have higher generalization levels with respect to their pollinators than natives. The consequences for network topology are that-rather than displacing native species fromthe network-plant invaders attracting pollinators into invaded modules tend to play new important topological roles (i.e. network hubs, module hubs and connectors) and cause role shifts in native species, creating larger modules that are more connected among each other.While the number of true compartmentswas lower in invaded compared with uninvaded networks, the effect of invasion on modularitywas contingent on the studysystem. Interestingly, the generalization level of the invasive plants partially explains this pattern, with more generalized invaders contributing to a lower modularity. Our findings indicate that the altered interaction structure of invaded networks makes them more robust against simulated random secondary species extinctions, but more vulnerable when the typically highly connected invasive plants go extinct first. The consequences and pathways by which biological invasions alter the interaction structure of plant-pollinator communities highlighted in this study may have important dynamical and functional implications, for example, by influencing multi-species reciprocal selection regimes and coevolutionary processes. © 2014 The Authors Published by the Royal Society. All rights reserved.


Naya D.E.,University of the Republic of Uruguay | Bozinovic F.,Linc Global
Evolutionary Ecology Research | Year: 2012

Background: Current models aimed at predicting the effect of climate change on future species distributions assume that all populations of a species are an undifferentiated collection of individuals with each individual having a tolerance range equal to that of the entire species. This assumption overestimates a species' ability to cope with climate change, but data to support better models are available only for a few species with commercial value. An alternative to detailed studies of intra-specific variation in plasticity is to identify global patterns in phenotypic plasticity. One such pattern may be the climatic variability hypothesis (CVH), which states that physiological flexibility should increase with climatic variability, and thus with latitude. Goal: Evaluate the latitudinal pattern predicted by the climatic variability hypothesis. Definitions: Routine metabolic rate (RMR) is the daily metabolic rate of an individual. Standard metabolic rate (SMR) is the minimum metabolic rate needed to sustain life processes at a given temperature. (Typically, RMR is nearly twice SMR.) Let metabolic scope (i.e. RMR -SMR) be a measure of physiological flexibility (see Naya et al., 2012). Methods: Download mass- and temperature-independent SMR and RMR for 38 fish species from the FishBase. Regress the metabolic scope of species against their body length, trophic position, distributional mid-point, distributional range, maximum depth, environmental temperatures, and thermal range within the distributional area. Results: Metabolic scope was positively correlated with species' distributional range and marginally correlated with the thermal range within species' distributional area. Conclusion: Given the pattern of variation in climatic variability with latitude in aquatic ecosystems, we expected that physiological flexibility in aquatic organisms should be closely related with species' distributional range rather than with latitudinal distributional mid-point, as was indeed the case for metabolic scope. © 2012 Daniel E. Naya.


Traveset A.,Linc Global
Proceedings. Biological sciences / The Royal Society | Year: 2013

The unique biodiversity of most oceanic archipelagos is currently threatened by the introduction of alien species that can displace native biota, disrupt native ecological interactions, and profoundly affect community structure and stability. We investigated the threat of aliens on pollination networks in the species-rich lowlands of five Galápagos Islands. Twenty per cent of all species (60 plants and 220 pollinators) in the pooled network were aliens, being involved in 38 per cent of the interactions. Most aliens were insects, especially dipterans (36%), hymenopterans (30%) and lepidopterans (14%). These alien insects had more links than either endemic pollinators or non-endemic natives, some even acting as island hubs. Aliens linked mostly to generalized species, increasing nestedness and thus network stability. Moreover, they infiltrated all seven connected modules (determined by geographical and phylogenetic constraints) of the overall network, representing around 30 per cent of species in two of them. An astonishingly high proportion (38%) of connectors, which enhance network cohesiveness, was also alien. Results indicate that the structure of these emergent novel communities might become more resistant to certain type of disturbances (e.g. species loss), while being more vulnerable to others (e.g. spread of a disease). Such notable changes in network structure as invasions progress are expected to have important consequences for native biodiversity maintenance.


Dispersal of individuals among subpopulations is a key process underlying metapopulation dynamics. Many metapopulation models, including those of coastal benthic organisms under marine reserve scenarios, have assumed a particular and time-independent dispersal pattern. The behavior of such models, however, may be sensitive to more realistic representations of oceanic dispersal. We examine the importance of environmental variability and dispersal characters for metapopulation persistence using a space-limited metapopulation model, in which the dispersal phase is represented by a connectivity matrix and environmental fluctuations by stochastic perturbations of adult abundances. The model is suited to marine organisms, but the same principles apply to other systems. When dispersal is asymmetrical, as expected in the presence of a dominant current, environmental variability can allow the metapopulation to persist, even when the per capita larval production rate is too low to otherwise sustain the population. This suggests that metapopulations inhabiting finite ranges in an advective environment may be more susceptible to variations related to climate change. Generalized stability theory is a powerful tool for identifying the local populations that have greatest impact on the metapopulation, and hence the optimal sites for protection from exploitation. We show that the inclusion of realistic environmental variability and complex dispersal patterns in models of marine reserve networks can bring unsuspected and sometimes largely positive effects for conservation and management of benthic species. Thus, marine reserve monitoring of abundance and recruitment in systems with longshore currents should include the region of longdistance dispersal of the species. © Inter-Research 2011.


Albrecht M.,Linc Global | Padron B.,Linc Global | Bartomeus I.,CSIC - Doñana Biological Station | Traveset A.,Linc Global
Proceedings. Biological sciences / The Royal Society | Year: 2014

Compartmentalization-the organization of ecological interaction networks into subsets of species that do not interact with other subsets (true compartments) or interact more frequently among themselves than with other species (modules)-has been identified as a key property for the functioning, stability and evolution of ecological communities. Invasions by entomophilous invasive plants may profoundly alter the way interaction networks are compartmentalized. We analysed a comprehensive dataset of 40 paired plant-pollinator networks (invaded versus uninvaded) to test this hypothesis. We show that invasive plants have higher generalization levels with respect to their pollinators than natives. The consequences for network topology are that-rather than displacing native species from the network-plant invaders attracting pollinators into invaded modules tend to play new important topological roles (i.e. network hubs, module hubs and connectors) and cause role shifts in native species, creating larger modules that are more connected among each other. While the number of true compartments was lower in invaded compared with uninvaded networks, the effect of invasion on modularity was contingent on the study system. Interestingly, the generalization level of the invasive plants partially explains this pattern, with more generalized invaders contributing to a lower modularity. Our findings indicate that the altered interaction structure of invaded networks makes them more robust against simulated random secondary species extinctions, but more vulnerable when the typically highly connected invasive plants go extinct first. The consequences and pathways by which biological invasions alter the interaction structure of plant-pollinator communities highlighted in this study may have important dynamical and functional implications, for example, by influencing multi-species reciprocal selection regimes and coevolutionary processes. © 2014 The Author(s) Published by the Royal Society. All rights reserved.


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