ORCID Profile
0000-0002-5156-2009
Current Organisation
Instituto Gulbenkian de Ciência
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Ecological Impacts of Climate Change | Ecology | Community Ecology | Ecological Physiology
ANZSRC Socio-Economic Objective (SEO)
Ecosystem Adaptation to Climate Change | Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Expanding Knowledge in the Biological Sciences |
Related Links
Publications
Energetic scaling across different host densities and its consequences for pathogen proliferation
Publisher: Wiley
Date: 08-12-2021
Abstract: The spread of infectious disease is determined by the ability of a pathogen to proliferate within and spread between susceptible hosts. Processes that limit the performance of a pathogen thus occur at two scales: varying with both the availability of energy within a host, and the number of susceptible hosts in a patch. When the rate at which a host intakes and expends energy is density‐dependent, these two processes are intimately linked. By modifying how hosts compete for and expend resources, a shift in population density may contribute to differences in the flow of energy in a host–pathogen system, both in terms of the energy available for a host to grow, reproduce and fight infection, as well as the energy available for a pathogen to exploit. Energy flux, therefore, connects the two contrasting scales of within‐ and between‐host dynamics by directly linking the proliferation of a pathogen to the number of hosts circulating within a patch. We use the host Daphnia magna to explore the relationship between energy intake and expenditure at various population densities, as estimated by feeding and metabolic rates respectively. By infecting hosts with the bacterial pathogen Pasteuria ramosa , we then explore how infection changes the relative balance of energy intake and expenditure, and how this energy scope translates into production of transmission spores. Our work demonstrates that energy intake declines at a faster rate with density than does metabolic rate, leaving more excess energy (i.e. discretionary energy) available for both hosts and their dependent pathogens at low population densities. This energetic advantage translates positively into host and pathogen growth, with the production of mature transmission spores benefiting most from correlated changes in host body size, as well as a direct connection between energy scope and spore loads. Our findings reinforce how patch quality for a pathogen operates at two contrasting scales, with the within‐host proliferation of a pathogen being optimised in energy rich, low density host populations and opportunities for between‐host transmission likely maximised in dense populations. A free Plain Language Summary can be found within the Supporting Information of this article.
Species interactions can maintain resistance of subtidal algal habitats to an increasingly modified world
Publisher: Elsevier BV
Date: 07-2015
Genome Size Affects Fitness in the Eukaryotic Alga Dunaliella tertiolecta
Publisher: Elsevier BV
Date: 09-2020
Metabolic scaling across succession: Do individual rates predict community‐level energy use?
Publisher: Wiley
Date: 06-2018
How to estimate community energy flux? A comparison of approaches reveals that size-abundance trade-offs alter the scaling of community energy flux
Publisher: The Royal Society
Date: 19-08-2020
Abstract: Size and metabolism are highly correlated, so that community energy flux might be predicted from size distributions alone. However, the accuracy of predictions based on interspecific energy–size relationships relative to approaches not based on size distributions is unknown. We compare six approaches to predict energy flux in phytoplankton communities across succession: assuming a constant energy use among species (per cell or unit biomass), using energy–size interspecific scaling relationships and species-specific rates (both with or without accounting for density effects). Except for the per cell approach, all others explained some variation in energy flux but their accuracy varied considerably. Surprisingly, the best approach overall was based on mean biomass-specific rates, followed by the most complex (species-specific rates with density). We show that biomass-specific rates alone predict community energy flux because the allometric scaling of energy use with size measured for species in isolation does not reflect the isometric scaling of these species in communities. We also find energy equivalence throughout succession, even when communities are not at carrying capacity. Finally, we discuss that species assembly can alter energy–size relationships, and that metabolic suppression in response to density might drive the allometry of community energy flux as biomass accumulates.
Ecological Resistance – Why Mechanisms Matter: A Reply to Sundstrom et al.
Publisher: Elsevier BV
Date: 06-2016
Beyond spatial and temporal averages: ecological responses to extreme events may be exacerbated by local disturbances
Publisher: Springer Science and Business Media LLC
Date: 30-09-2015
Testing MacArthur's minimisation principle: do communities minimise energy wastage during succession?
Publisher: Wiley
Date: 20-05-2018
DOI: 10.1111/ELE.13087
Abstract: Robert MacArthur developed a theory of community assembly based on competition. By incorporating energy flow, MacArthur's theory allows for predictions of community function. A key prediction is that communities minimise energy wastage over time, but this minimisation is a trade-off between two conflicting processes: exploiting food resources, and maintaining low metabolism and mortality. Despite its simplicity and elegance, MacArthur's principle has not been tested empirically despite having long fascinated theoreticians. We used a combination of field chronosequence experiments and laboratory assays to estimate how the energy wastage of a community changes during succession. We found that older successional stages wasted more energy in maintenance, but there was no clear pattern in how communities of different age exploited food resources. We identify several reasons for why MacArthur's original theory may need modification and new avenues to further explore community efficiency, an understudied component of ecosystem functioning.
Ecological impacts of invading seaweeds: a meta‐analysis of their effects at different trophic levels
Publisher: Wiley
Date: 10-10-2014
DOI: 10.1111/DDI.12264
Resisting regime-shifts: the stabilising effect of compensatory processes
Publisher: Elsevier BV
Date: 09-2015
DOI: 10.1016/J.TREE.2015.06.014
Abstract: Ecologists seem predisposed to studying change because we are intuitively interested in dynamic systems, including their vulnerability to human disturbance. We contrast this disposition with the value of studying processes that work against change. Although powerful, processes that counter disturbance often go unexplored because they yield no observable community change. This stability results from compensatory processes which are initiated by disturbance these adjust in proportion to the strength of the disturbance to prevent community change. By recognising such buffering processes, we might also learn to recognise the early warning signals of community shifts which are notoriously difficult to predict because communities often show little to no change before their tipping point is reached.
Climate-driven disparities among ecological interactions threaten kelp forest persistence
Publisher: Wiley
Date: 06-08-2017
DOI: 10.1111/GCB.13414
Abstract: The combination of ocean warming and acidification brings an uncertain future to kelp forests that occupy the warmest parts of their range. These forests are not only subject to the direct negative effects of ocean climate change, but also to a combination of unknown indirect effects associated with changing ecological landscapes. Here, we used mesocosm experiments to test the direct effects of ocean warming and acidification on kelp biomass and photosynthetic health, as well as climate-driven disparities in indirect effects involving key consumers (urchins and rock lobsters) and competitors (algal turf). Elevated water temperature directly reduced kelp biomass, while their turf-forming competitors expanded in response to ocean acidification and declining kelp canopy. Elevated temperatures also increased growth of urchins and, concurrently, the rate at which they thinned kelp canopy. Rock lobsters, which are renowned for keeping urchin populations in check, indirectly intensified negative pressures on kelp by reducing their consumption of urchins in response to elevated temperature. Overall, these results suggest that kelp forests situated towards the low-latitude margins of their distribution will need to adapt to ocean warming in order to persist in the future. What is less certain is how such adaptation in kelps can occur in the face of intensifying consumptive (via ocean warming) and competitive (via ocean acidification) pressures that affect key ecological interactions associated with their persistence. If such indirect effects counter adaptation to changing climate, they may erode the stability of kelp forests and increase the probability of regime shifts from complex habitat-forming species to more simple habitats dominated by algal turfs.
Phytoplankton diversity affects biomass and energy production differently during community development
Publisher: Wiley
Date: 04-11-2021
Abstract: Bio ersity determines the productivity and stability of ecosystems but some aspects of bio ersity–ecosystem functioning relationships remain poorly resolved. One key uncertainty is the inter‐relationship between bio ersity, energy and biomass production as communities develop over time. Energy production drives biomass accumulation but the ratio of the two processes can change during community development. How bio ersity affects these temporal patterns remains unknown. We empirically assessed how species ersity mediates the rates of increase and maximum values of biomass and net energy production in experimental phytoplankton communities over 10 days in the laboratory. We used five phytoplankton species to assemble three levels of ersity (monocultures, bicultures and communities) and we quantify their changes in biomass production and energy fluxes (energy produced by photosynthesis, consumed by metabolism, and net energy production as their difference) as the cultures move from a low density, low competition system to a high density, high competition system. We find that species ersity affects both biomass and energy fluxes but in different ways. Diverse communities produce net energy and biomass at faster rates, reaching greater maximum biomass but with no difference in maximum net energy production. Bounds on net energy production seem stronger than those on biomass because competition limits energy fluxes as biomass accumulates over time. In summary, ersity initially enhances productivity by diffusing competitive interactions but metabolic density dependence reduces these positive effects as biomass accumulates in older communities. By showing how bio ersity affects both biomass and energy fluxes during community development, our results demonstrate a mechanism that underlies positive bio ersity effects and offer a framework for comparing bio ersity effects across systems at different stages of development and disturbance regimes. A free Plain Language Summary can be found within the Supporting Information of this article.
Variation in the structure of subtidal landscapes in the NW Mediterranean Sea
Publisher: Inter-Research Science Center
Date: 21-06-2012
DOI: 10.3354/MEPS09703
Potential effects of storm-water run-off on assemblages of mobile invertebrates
Publisher: Inter-Research Science Center
Date: 20-10-2011
DOI: 10.3354/MEPS09307
Conspecific chemical cues drive density-dependent metabolic suppression independently of resource intake
Publisher: The Company of Biologists
Date: 2020
DOI: 10.1242/JEB.224824
Abstract: Within species, in iduals of the same size can vary substantially in their metabolic rate. One source of variation in metabolism is conspecific density – in iduals in denser populations may have lower metabolism than those in sparser populations. However, the mechanisms through which conspecifics drive metabolic suppression remain unclear. While food competition is a potential driver, other density-mediated factors could act independently or in combination to drive metabolic suppression but these drivers have rarely been investigated. We used sessile marine invertebrates to test how food availability interacts with oxygen availability, water flow and chemical cues to affect metabolism. We show that conspecific chemical cues induce metabolic suppression independently of food and this metabolic reduction is associated with the downregulation of physiological processes rather than feeding activity. Conspecific cues should be considered when predicting metabolic variation and competitive outcomes as they are an important, but underexplored, source of variation in metabolic traits.
Metabolic evolution in response to interspecific competition in a eukaryote
Publisher: Cold Spring Harbor Laboratory
Date: 21-10-2022
DOI: 10.1101/2022.10.19.512836
Abstract: Competition can drive rapid evolution which, in turn, alters the trajectory of ecological communities. The role of eco-evolutionary dynamics in ecological communities is increasingly well-appreciated, but a mechanistic framework for identifying the types of traits that will evolve, and their trajectories, is required. Metabolic theory makes explicit predictions about how competition should shape the evolution of metabolism and size but these predictions have gone largely untested, particularly in eukaryotes. We use experimental evolution of a eukaryotic phototroph to examine how metabolism, size, and demography coevolve under both inter- and intra-specific competition. We find that the focal species evolves a smaller body size in response to competition, reducing density-dependence and maximizing carrying capacity. Metabolic theory successfully predicted most of these adaptations, but we also find important departures from theory. Longer-term evolution (70 generations) led to Pareto improvements in both population growth rate and carrying capacity, suggesting that classic r-K trade-offs observed among species can be evaded within species. The evasion of this trade-off appeared to arise due to the rapid evolution of enhanced metabolic plasticity: lineages exposed to competition evolved more labile metabolisms that tracked resource availability more effectively than lineages that were competition-free. We predict that rapid evolution in both size and metabolism may be a ubiquitous feature of adaptation to changing resource regimes that occur via species invasions and environmental change.
Managing local coastal stressors to reduce the ecological effects of ocean acidification and warming
Publisher: MDPI AG
Date: 10-10-2013
DOI: 10.3390/W5041653
Does energy flux predict density‐dependence? An empirical field test
Publisher: Wiley
Date: 08-11-2017
DOI: 10.1002/ECY.2033
Abstract: Changes in population density alter the availability, acquisition, and expenditure of resources by in iduals, and consequently their contribution to the flux of energy in a system. While both negative and positive density-dependence have been well studied in natural populations, we are yet to estimate the underlying energy flows that generate these patterns and the ambivalent effects of density make prediction difficult. Ultimately, density-dependence should emerge from the effects of conspecifics on rates of energy intake (feeding) and expenditure (metabolism) at the organismal level, thus determining the discretionary energy available for growth. Using a model system of colonial marine invertebrates, we measured feeding and metabolic rates across a range of population densities to calculate how discretionary energy per colony changes with density and test whether this energy predicts observed patterns in organismal size across densities. We found that both feeding and metabolic rates decline with density but that feeding declines faster, and that this discrepancy is the source of density-dependent reductions in in idual growth. Importantly, we could predict the size of our focal organisms after eight weeks in the field based on our estimates of energy intake and expenditure. The effects of density on both energy intake and expenditure overwhelmed the effects of body size even though higher density populations had smaller colonies (with higher mass-specific biological rates), density effects meant that these smaller colonies had lower mass-specific rates overall. Thus, to predict the contribution of organisms to the flux of energy in populations, it seems necessary not only to quantify how rates of energy intake and expenditure scale with body size, but also how they scale with density given that this ecological constraint can be a stronger driver of energy use than the physiological constraint of body size.
Community efficiency during succession: a test of MacArthur's minimization principle in phytoplankton communities
Publisher: Wiley
Date: 17-03-2020
DOI: 10.1002/ECY.3015
Moving ocean acidification research beyond a simple science: Investigating ecological change and their stabilizers
Publisher: Elsevier BV
Date: 12-2017
Organismal homeostasis buffers the effects of abiotic change on community dynamics
Publisher: Wiley
Date: 09-2016
DOI: 10.1002/ECY.1488
Abstract: The problem of linking fine-scale processes to broad-scale patterns remains a central challenge of ecology. As rates of abiotic change intensify, there is a critical need to understand how in idual responses aggregate to generate compensatory dynamics that stabilize community processes. Notably, while local and global resource enhancement (e.g., nutrient and CO
Metabolic evolution in response to interspecific competition in a eukaryote
Publisher: Elsevier BV
Date: 07-2023
Trophic compensation reinforces resistance: herbivory absorbs the increasing effects of multiple disturbances
Publisher: Wiley
Date: 11-01-2015
DOI: 10.1111/ELE.12405
Abstract: Disturbance often results in small changes in community structure, but the probability of transitioning to contrasting states increases when multiple disturbances combine. Nevertheless, we have limited insights into the mechanisms that stabilise communities, particularly how perturbations can be absorbed without restructuring (i.e. resistance). Here, we expand the concept of compensatory dynamics to include countervailing mechanisms that absorb disturbances through trophic interactions. By definition, 'compensation' occurs if a specific disturbance stimulates a proportional countervailing response that eliminates its otherwise unchecked effect. We show that the compounding effects of disturbances from local to global scales (i.e. local canopy-loss, eutrophication, ocean acidification) increasingly promote the expansion of weedy species, but that this response is countered by a proportional increase in grazing. Finally, we explore the relatively unrecognised role of compensatory effects, which are likely to maintain the resistance of communities to disturbance more deeply than current thinking allows.
Related Organisations
Universita Degli Studi Di Ferrara Dipartimento Di Fisica E Scienze Della Terra
Location: Italy
Related Funding Activities
Competition And The Evolution Of Energy Fluxes In Communities
Start Date: 2021
End Date: 2024
Funder: “la Caixa” Foundation
View Funded ActivityCompetition And The Evolution Of Energy Fluxes In Communities
Start Date: 2021
End Date: 2024
Funder: Caixabank SA
View Funded ActivityUnravelling The Impacts Of Global Warming On Whole Ecological Communities
Start Date: 2019
End Date: 2021
Funder: Australian Research Council
View Funded ActivityDiscovery Early Career Researcher Award - Grant ID: DE190100660
Start Date: 01-2019
End Date: 11-2021
Amount: $409,805.00
Funder: Australian Research Council
View Funded Activity