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

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. Source

Traveset A.,Linc Global
Proceedings. Biological sciences / The Royal Society

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. Source

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

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. Source

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

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. Source

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

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. Source

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