ORCID Profile
0000-0003-2857-7904
Current Organisation
Princeton University
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Publisher: Wiley
Date: 18-11-2022
Abstract: Understanding the traits mediating species' responses to climate change is a cornerstone for predicting future community composition and ecosystem function. Although species' eco‐physiological properties determine their response to environmental change, most trait‐based studies focus on a small subset of easily measured morphological traits as proxies for physiology. This choice may limit our ability to predict the impacts of climate change on species' demography, and obscure the underlying mechanisms. We conducted a transplantation experiment along a 1000‐m elevation gradient in the Alps to quantify the degree to which changes in plant abundance due to climate warming were predicted by eco‐physiological performance versus common morphological traits. Physiological measurements revealed that warming favoured species with a conservative leaf‐level water use strategy whereas species whose leaf‐level water use was more ‘wasteful’ were more likely to suffer from the warmer and drier climate. Nevertheless, the predictive power of physiological traits did not exceed that of morphological traits. Our results, therefore, show that while easily measured morphological traits can successfully predict plant abundance responses to climate, eco‐physiological approaches are needed to understand the underlying mechanism. Read the free Plain Language Summary for this article on the Journal blog.
Publisher: Proceedings of the National Academy of Sciences
Date: 18-01-2019
Abstract: Increasing evidence for rapid evolution suggests that the maintenance of species ersity in ecological communities may be influenced by more than purely ecological processes. Classic theory shows that interspecific competition may select for traits that increase niche differentiation, weakening competition and thus promoting species coexistence. While empirical work has demonstrated trait evolution in response to competition, if and how evolution affects the dynamics of the competing species—the key step for completing the required eco-evolutionary feedback—has been difficult to resolve. Here, we show that evolution in response to interspecific competition feeds back to change the course of competitive population dynamics of aquatic plant species over 10–15 generations in the field. By manipulating selection imposed by heterospecific competitors in experimental ponds, we demonstrate that ( i ) interspecific competition drives rapid genotypic change, and ( ii ) this evolutionary change in one competitor, while not changing the coexistence outcome, causes the population trajectories of the two competing species to converge. In contrast to the common expectation that interspecific competition should drive the evolution of niche differentiation, our results suggest that genotypic evolution resulted in phenotypic changes that altered population dynamics by affecting the competitive hierarchy. This result is consistent with theory suggesting that competition for essential resources can limit opportunities for the evolution of niche differentiation. Our finding that rapid evolution regulates the dynamics of competing species suggests that ecosystems may rely on continuous feedbacks between ecology and evolution to maintain species ersity.
Publisher: MDPI AG
Date: 03-2023
DOI: 10.3390/ANTIBIOTICS12030492
Abstract: The human population is growing and urbanising. These factors are driving the demand for animal-sourced proteins. The rising demand is favouring livestock intensification, a process that frequently relies on antibiotics for growth promotion, treatment and prevention of diseases. Antibiotic use in livestock production requires strict adherence to the recommended withdrawal periods. In Kenya, the risk of residues in meat is particularly high due to lack of legislation requiring testing for antibiotic residues in meat destined for the local market. We examined pig carcasses for gross pathological lesions and collected pork s les for antibiotic residue testing. Our aim was to determine if a risk-based approach to residue surveillance may be adopted by looking for an association between lesions and presence of residues. In total, 387 pork s les were tested for antibiotic residues using the Premi®Test micro-inhibition kit. The prevalence of antibiotic residues was 41.26% (95% CI, 34.53–48.45%). A logistic regression model found no significant associations between gross pathological lesions and the presence of antibiotic residues. We recommend that the regulating authorities strongly consider routine testing of carcasses for antibiotic residues to protect meat consumers. Future studies should research on farming practices contributing to the high prevalence of residues.
Publisher: Wiley
Date: 12-08-2022
DOI: 10.1111/ELE.14078
Abstract: Community ecology typically assumes that competitive exclusion and species coexistence are unaffected by evolution on the time scale of ecological dynamics. However, recent studies suggest that rapid evolution operating concurrently with competition may enable species coexistence. Such findings necessitate general theory that incorporates the coexistence contributions of eco-evolutionary processes in parallel with purely ecological mechanisms and provides metrics for quantifying the role of evolution in shaping competitive outcomes in both modelling and empirical contexts. To foster the development of such theory, here we extend the interpretation of the two principal metrics of modern coexistence theory-niche and competitive ability differences-to systems where competitors evolve. We define eco-evolutionary versions of these metrics by considering how invading and resident species adapt to conspecific and heterospecific competitors. We show that the eco-evolutionary niche and competitive ability differences are sums of ecological and evolutionary processes, and that they accurately predict the potential for stable coexistence in previous theoretical studies of eco-evolutionary dynamics. Finally, we show how this theory frames recent empirical assessments of rapid evolution effects on species coexistence, and how empirical work and theory on species coexistence and eco-evolutionary dynamics can be further integrated.
Publisher: Wiley
Date: 02-06-2016
DOI: 10.1111/ELE.12618
Abstract: Although the effects of variation between in iduals within species are traditionally ignored in studies of species coexistence, the magnitude of intraspecific variation in nature is forcing ecologists to reconsider. Compelling intuitive arguments suggest that in idual variation may provide a previously unrecognised route to ersity maintenance by blurring species-level competitive differences or substituting for species-level niche differences. These arguments, which are motivating a large body of empirical work, have rarely been evaluated with quantitative theory. Here we incorporate intraspecific variation into a common model of competition and identify three pathways by which this variation affects coexistence: (1) changes in competitive dynamics because of nonlinear averaging, (2) changes in species' mean interaction strengths because of variation in underlying traits (also via nonlinear averaging) and (3) effects on stochastic demography. As a consequence of the first two mechanisms, we find that intraspecific variation in competitive ability increases the dominance of superior competitors, and intraspecific niche variation reduces species-level niche differentiation, both of which make coexistence more difficult. In addition, in idual variation can exacerbate the effects of demographic stochasticity, and this further destabilises coexistence. Our work provides a theoretical foundation for emerging empirical interests in the effects of intraspecific variation on species ersity.
Publisher: Wiley
Date: 26-08-2022
DOI: 10.1111/ELE.14087
Abstract: Forecasting the trajectories of species assemblages in response to ongoing climate change requires quantifying the time lags in the demographic and ecological processes through which climate impacts species' abundances. Since experimental climate manipulations are typically abrupt, the observed species responses may not match their responses to gradual climate change. We addressed this problem by transplanting alpine grassland turfs to lower elevations, recording species' demographic responses to climate and competition, and using these data to parameterise community dynamics models forced by scenarios of gradual climate change. We found that shifts in community structure following an abrupt climate manipulation were not simply accelerated versions of shifts expected under gradual warming, as the former missed the transient rise of species benefiting from moderate warming. Time lags in demography and species interactions controlled the pace and trajectory of changing species' abundances under simulated 21st-century climate change, and thereby prevented immediate ersity loss.
Publisher: Wiley
Date: 25-08-2014
DOI: 10.1111/GEB.12219
Abstract: Environmentally cued germination and seed banking are strategies employed by annual plants to persist in unpredictable climates. Moreover, such strategies may be key to persistence under more extreme and variable future climates. In regions with a mediterranean climate, cold‐cued germination can allow populations to avoid germinating under unfavourable conditions and seed banks can buffer population growth in the face of inter‐annual climate variability. Using widespread native annual plant species in the C alifornia Floristic Province ( CFP ), we ask: (1) How common are cold‐cued germination and persistent seed banks? (2) Does the prevalence of cold‐cued germination and seed bank maintenance shift predictably with climate? (3) Are germination strategies taxonomically linked? C alifornia, USA . We assessed seed bank persistence and temperature‐cued germination in c . 175 populations of 42 species (eight families) from across C alifornia in the 2006 growing season. We then tested for evidence that the prevalence of these adaptations correlated with latitude, increasing climate variability and taxonomy. Only 19% of populations had significantly cold‐cued seed germination and only 52% of populations had detectable seed banks. There were no significant relationships between the prevalence of cold‐cued germination and any climate factor. Seed banking was significantly more common in regions with warm, dry conditions in the preceding year, but was not related to long‐term climate averages. Variance in temperature‐cued germination was best explained at the species level, with no variance explained by family. Our results suggest that germination of annual plants in the CFP is dominated by general risk aversion strategies rather than locally adaptive strategies linked to long‐term climate factors. High germination variability within and among populations, coupled with increased seed banking under less favourable conditions, suggests that germination strategies are unlikely to limit this flora's persistence under an increasingly harsh and unpredictable climate.
Publisher: Wiley
Date: 06-03-2022
Abstract: Sympatric large mammalian herbivore species differ in diet composition, both by eating different parts of the same plant and by eating different plant species. Various theories proposed to explain these differences are not mutually exclusive, but are difficult to reconcile and confront with data. Moreover, whereas several of these ideas were originally developed with reference to within‐plant partitioning (i.e. consumption of different tissues), they may analogously apply to partitioning of plant species this possibility has received little attention. Plant functional traits provide a novel window into herbivore diets and a means of testing multiple hypotheses in a unified framework. We used DNA metabarcoding to characterize the diets of 14 sympatric large‐herbivore species in an African savanna and analysed diet composition in light of 27 functional traits that we measured locally for 204 plant species. Plant traits associated with the deep phylogenetic split between grasses and eudicots formed the primary axis of resource partitioning, affirming the generality and importance of the grazer–browser spectrum. A secondary axis comprised plant traits relevant to herbivore body size. Plant taxa in the diets of large‐bodied species were lower on average in digestible energy and protein, taller on average (especially among grazers), and tended to be higher in tensile strength, zinc, stem‐specific density, and potassium (and lower in sodium, stem dry matter content, and copper). These results are consistent with longstanding hypotheses linking body size with forage quality and height, yet they also suggest the existence of undiscovered links between herbivore body size and a set of rarely considered food–plant traits. We also tested the novel hypothesis that the leaf economic spectrum (LES), a major focus in plant ecology, is an axis of resource partitioning in large‐herbivore assemblages we found that the LES was a minor axis of in idual variation within a few species, but had little effect on interspecific dietary differentiation. Synthesis . These results identify key plant traits that underpin the partitioning of food–plant species in large‐herbivore communities and suggest that accounting for multiple plant traits (and trade‐offs among them) will enable a deeper understanding of herbivore–plant interaction networks.
Publisher: Annual Reviews
Date: 12-2012
DOI: 10.1146/ANNUREV-ECOLSYS-110411-160411
Abstract: Although research on the role of competitive interactions during community assembly began decades ago, a recent revival of interest has led to new discoveries and research opportunities. Using contemporary coexistence theory that emphasizes stabilizing niche differences and relative fitness differences, we evaluate three empirical approaches for studying community assembly. We show that experimental manipulations of the abiotic or biotic environment, assessments of trait-phylogeny-environment relationships, and investigations of frequency-dependent population growth all suggest strong influences of stabilizing niche differences and fitness differences on the outcome of plant community assembly. Nonetheless, due to the limitations of these approaches applied in isolation, we still have a poor understanding of which niche axes and which traits determine the outcome of competition and community structure. Combining current approaches represents our best chance of achieving this goal, which is fundamental to conceptual ecology and to the management of plant communities under global change.
Publisher: MDPI AG
Date: 13-10-2023
Publisher: Elsevier BV
Date: 11-2016
Publisher: Wiley
Date: 23-06-2010
DOI: 10.1111/J.1461-0248.2010.01509.X
Abstract: Though many processes are involved in determining which species coexist and assemble into communities, competition is among the best studied. One hypothesis about competition's contribution to community assembly is that more closely related species are less likely to coexist. Though empirical evidence for this hypothesis is mixed, it remains a common assumption in certain phylogenetic approaches for inferring the effects of environmental filtering and competitive exclusion. Here, we relate modern coexistence theory to phylogenetic community assembly approaches to refine expectations for how species relatedness influences the outcome of competition. We argue that two types of species differences determine competitive exclusion with opposing effects on relatedness patterns. Importantly, this means that competition can sometimes eliminate more different and less related taxa, even when the traits underlying the relevant species differences are phylogenetically conserved. Our argument leads to a reinterpretation of the assembly processes inferred from community phylogenetic structure.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United States of America
Location: United States of America
Location: United States of America
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No related grants have been discovered for Jonathan Levine.