Positively and negatively autocorrelated environmental fluctuations have opposing effects on species coexistence

Priority Effects ◽

Adult Survival ◽

Storage Effect ◽

Competing Species ◽

Demographic Rates ◽

Environmental Fluctuations ◽

Environmental Responses ◽

Species Specific ◽

Strength Of Competition

AbstractEnvironmental fluctuations can mediate coexistence between competing species via the storage effect. This fluctuation-dependent coexistence mechanism requires three conditions: (i) a positive covariance between environment conditions and the strength of competition, (ii) species-specific environmental responses, and (iii) species are less sensitive to competition in environmentally unfavorable years. In serially uncorrelated environments, condition (i) only occurs if favorable environmental conditions immediately and directly increase the strength of competition. For many demographic parameters, this direct link between favorable years and competition may not exist. Moreover, many environmental variables are temporal autocorrelated, but theory has largely focused on serially uncorrelated environments. To address this gap, a model of competing species in autocorrelated environments is analyzed. This analysis shows that positive autocorrelations in demographic rates that increase fitness (e.g. maximal fecundity or adult survival) produce the positive environment-competition covariance. Hence, when these demographic rates contribute to buffered population growth, positive temporal autocorrelations generate a storage effect, otherwise they destabilize competitive interactions. For negatively autocorrelated environments, this theory highlights an alternative stabilizing mechanism that requires three conditions: (i’) a negative environmental-competition covariance, (ii) species-specific environmental responses, and (iii’) species are less sensitive to competition in more favorable years. When the conditions for either of these stabilizing mechanisms are violated, temporal autocorrelations can generate stochastic priority effects or hasten competitive exclusion. Collectively, these results highlight that temporal autocorrelations in environmental conditions can play a fundamental role in determining ecological outcomes of competing species.

What is the storage effect, why should it occur in cancers, and how can it inform cancer therapy?

10.1101/2020.03.28.013557 ◽

2020 ◽

Cited By ~ 1

Author(s):

Anna K. Miller ◽

Joel S. Brown ◽

David Basanta ◽

Nancy Huntly

Keyword(s):

Tumor Microenvironment ◽

Cancer Cell ◽

Treatment Resistance ◽

Cell Types ◽

Intratumor Heterogeneity ◽

Storage Effect ◽

Ecological Communities ◽

Substantial Impact ◽

Environmental Responses ◽

Intratumor heterogeneity is a feature of cancer that is associated with progression, treatment resistance, and recurrence. However, the mechanisms that allow diverse cancer cell lineages to coexist remain poorly understood. The storage effect is a coexistence mechanism that has been proposed to explain the diversity of a variety of ecological communities, including coral reef fish, plankton and desert annual plants. Three ingredients are required for there to be a storage effect: 1) temporal variability in the environment, 2) buffered population growth, and 3) species-specific environmental responses. Here, we argue that these conditions are observed in cancers and that it is likely that the storage effect contributes to intratumor diversity. Data that show the temporal variation within the tumor microenvironment is needed to quantify how cancer cells respond to fluctuations in the tumor microenvironment and what impact this has on interactions among cancer cell types. The presence of a storage effect within a patient’s tumors could have substantial impact on how we understand and treat cancer.

What Is the Storage Effect, Why Should It Occur in Cancers, and How Can It Inform Cancer Therapy?

Cancer Control ◽

10.1177/1073274820941968 ◽

2020 ◽

Vol 27 (3) ◽

pp. 107327482094196

Author(s):

Anna K. Miller ◽

Joel S. Brown ◽

David Basanta ◽

Nancy Huntly

Keyword(s):

Tumor Microenvironment ◽

Cancer Cell ◽

Treatment Resistance ◽

Cell Types ◽

Intratumor Heterogeneity ◽

Storage Effect ◽

Ecological Communities ◽

Substantial Impact ◽

Environmental Responses ◽

Intratumor heterogeneity is a feature of cancer that is associated with progression, treatment resistance, and recurrence. However, the mechanisms that allow diverse cancer cell lineages to coexist remain poorly understood. The storage effect is a coexistence mechanism that has been proposed to explain the diversity of a variety of ecological communities, including coral reef fish, plankton, and desert annual plants. Three ingredients are required for there to be a storage effect: (1) temporal variability in the environment, (2) buffered population growth, and (3) species-specific environmental responses. In this article, we argue that these conditions are observed in cancers and that it is likely that the storage effect contributes to intratumor diversity. Data that show the temporal variation within the tumor microenvironment are needed to quantify how cancer cells respond to fluctuations in the tumor microenvironment and what impact this has on interactions among cancer cell types. The presence of a storage effect within a patient’s tumors could have a substantial impact on how we understand and treat cancer.

Environmental and taxonomic controls of carbon and oxygen stable isotope composition in Sphagnum across broad climatic and geographic ranges

Biogeosciences ◽

10.5194/bg-15-5189-2018 ◽

2018 ◽

Vol 15 (16) ◽

pp. 5189-5202 ◽

Cited By ~ 13

Author(s):

Gustaf Granath ◽

Håkan Rydin ◽

Jennifer L. Baltzer ◽

Fia Bengtsson ◽

Nicholas Boncek ◽

...

Keyword(s):

Large Scale ◽

Net Primary Productivity ◽

Isotope Composition ◽

Explanatory Power ◽

Isotopic Signature ◽

Co2 Uptake ◽

Δ13c Values ◽

Site Variation ◽

Abstract. Rain-fed peatlands are dominated by peat mosses (Sphagnum sp.), which for their growth depend on nutrients, water and CO2 uptake from the atmosphere. As the isotopic composition of carbon (12,13C) and oxygen (16,18O) of these Sphagnum mosses are affected by environmental conditions, Sphagnum tissue accumulated in peat constitutes a potential long-term archive that can be used for climate reconstruction. However, there is inadequate understanding of how isotope values are influenced by environmental conditions, which restricts their current use as environmental and palaeoenvironmental indicators. Here we tested (i) to what extent C and O isotopic variation in living tissue of Sphagnum is species-specific and associated with local hydrological gradients, climatic gradients (evapotranspiration, temperature, precipitation) and elevation; (ii) whether the C isotopic signature can be a proxy for net primary productivity (NPP) of Sphagnum; and (iii) to what extent Sphagnum tissue δ18O tracks the δ18O isotope signature of precipitation. In total, we analysed 337 samples from 93 sites across North America and Eurasia using two important peat-forming Sphagnum species (S. magellanicum, S. fuscum) common to the Holarctic realm. There were differences in δ13C values between species. For S. magellanicum δ13C decreased with increasing height above the water table (HWT, R2=17 %) and was positively correlated to productivity (R2=7 %). Together these two variables explained 46 % of the between-site variation in δ13C values. For S. fuscum, productivity was the only significant predictor of δ13C but had low explanatory power (total R2=6 %). For δ18O values, approximately 90 % of the variation was found between sites. Globally modelled annual δ18O values in precipitation explained 69 % of the between-site variation in tissue δ18O. S. magellanicum showed lower δ18O enrichment than S. fuscum (−0.83 ‰ lower). Elevation and climatic variables were weak predictors of tissue δ18O values after controlling for δ18O values of the precipitation. To summarize, our study provides evidence for (a) good predictability of tissue δ18O values from modelled annual δ18O values in precipitation, and (b) the possibility of relating tissue δ13C values to HWT and NPP, but this appears to be species-dependent. These results suggest that isotope composition can be used on a large scale for climatic reconstructions but that such models should be species-specific.

A Bayesian hierarchical approach to improve model parameter estimates and predictions of silage maize phenology in Germany

10.5194/egusphere-egu21-7962 ◽

2021 ◽

Author(s):

Michelle Viswanathan ◽

Tobias KD Weber ◽

Andreas Scheidegger ◽

Thilo Streck

Keyword(s):

Plant Phenology ◽

Parameter Estimates ◽

Crop Species ◽

Bayesian Hierarchical ◽

Crop Models ◽

Hierarchical Framework ◽

Silage Maize ◽

Parameterized Model ◽

Crop models are used to evaluate the impact of climate change on food security by simulating plant phenology, yield, biomass and leaf area index. Plant phenology defines the timing of crucial growth stages and physiological processes that influence organ appearance and assimilate partitioning. It is governed by environmental factors such as solar radiation, temperature and water availability. Plant phenology is not only specific for the crop species, but also depends on the cultivar. Additionally, growth of a cultivar could vary depending on the environment. Common crop models cannot fully capture the influence of the environment on phenology, resulting in cultivar-specific parameters that are environment-dependent. These parameter estimates may be unreliable in case of limited data. Moreover, crucial species-specific information is ignored. On the other hand, in large regional-scale models covering multiple cultivars and environments, information about the cultivars grown is generally not available. In this case, a shared set of parameters for the crop species would suppress within-species differences leading to unreliable predictions.A Bayesian hierarchical framework enables us to alleviate these problems by honouring the multi-level data structure. Additionally, we can reflect the uncertainty from different sources, for example, model inputs and measurements. In this study we implement a Bayesian hierarchical framework to estimate parameters of the Soil-Plant-Atmosphere System Simulation (SPASS) model for simulating phenological development of different cultivars of silage maize grown over all the contrasting climatological regions of Germany.We used data from the German weather service on the phenological development stages of silage maize grown across Germany between 2009 and 2019. During this period, silage maize was grown in over 3000 unique location-year combinations. Maize crops were differentiated into early, mid-early, mid-late and late ripening groups and were further classified into cultivars within each ripening group. Within the hierarchical framework, we estimate maize species-specific parameters as well as parameters per ripening group and cultivar, through Bayesian model calibration. We analyse the influence of environmental conditions on parameter estimates, to further develop the hierarchical structure. We perform cross-validation to assess the prediction quality of the parameterized model.With this approach, we show that robust parameter estimates account for differences between cultivars, ripening groups as well as different environmental conditions. The parameterized model can be used for large-scale phenology predictions of silage maize grown across Germany. These parameter estimates may perform better than independent species- or cultivar-specific estimates, in predicting phenology of future cultivars where specific cultivar characteristics are not known.

Diversity of parental environments increases phenotypic variation in Arabidopsis populations more than genetic diversity but similarly affects productivity

Annals of Botany ◽

10.1093/aob/mcaa100 ◽

2020 ◽

Cited By ~ 1

Author(s):

Javier Puy ◽

Carlos P Carmona ◽

Hana Dvořáková ◽

Vít Latzel ◽

Francesco de Bello

Keyword(s):

Genetic Diversity ◽

Phenotypic Variation ◽

Ecosystem Functioning ◽

Phenotypic Variability ◽

Population Type ◽

Diversity Effect ◽

Environmental Fluctuations ◽

Intraspecific Trait Variability ◽

Trait Variability

Abstract Background and Aims The observed positive diversity effect on ecosystem functioning has rarely been assessed in terms of intraspecific trait variability within populations. Intraspecific phenotypic variability could stem both from underlying genetic diversity and from plasticity in response to environmental cues. The latter might derive from modifications to a plant’s epigenome and potentially last multiple generations in response to previous environmental conditions. We experimentally disentangled the role of genetic diversity and diversity of parental environments on population productivity, resistance against environmental fluctuations and intraspecific phenotypic variation. Methods A glasshouse experiment was conducted in which different types of Arabidopsis thaliana populations were established: one population type with differing levels of genetic diversity and another type, genetically identical, but with varying diversity levels of the parental environments (parents grown in the same or different environments). The latter population type was further combined, or not, with experimental demethylation to reduce the potential epigenetic diversity produced by the diversity of parental environments. Furthermore, all populations were each grown under different environmental conditions (control, fertilization and waterlogging). Mortality, productivity and trait variability were measured in each population. Key Results Parental environments triggered phenotypic modifications in the offspring, which translated into more functionally diverse populations when offspring from parents grown under different conditions were brought together in mixtures. In general, neither the increase in genetic diversity nor the increase in diversity of parental environments had a remarkable effect on productivity or resistance to environmental fluctuations. However, when the epigenetic variation was reduced via demethylation, mixtures were less productive than monocultures (i.e. negative net diversity effect), caused by the reduction of phenotypic differences between different parental origins. Conclusions A diversity of environmental parental origins within a population could ameliorate the negative effect of competition between coexisting individuals by increasing intraspecific phenotypic variation. A diversity of parental environments could thus have comparable effects to genetic diversity. Disentangling the effect of genetic diversity and that of parental environments appears to be an important step in understanding the effect of intraspecific trait variability on coexistence and ecosystem functioning.

A multi-disciplinary comparison of great ape gut microbiota in a central African forest and European zoo

Scientific Reports ◽

10.1038/s41598-020-75847-3 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Victor Narat ◽

Katherine R. Amato ◽

Noémie Ranger ◽

Maud Salmona ◽

Séverine Mercier-Delarue ◽

...

Keyword(s):

Gut Microbiota ◽

Bacterial Diversity ◽

Participant Observation ◽

Feeding Habits ◽

Animal Health ◽

Structured Interviews ◽

Microbial Composition ◽

Species Specific ◽

Free Ranging

Abstract Comparisons of mammalian gut microbiota across different environmental conditions shed light on the diversity and composition of gut bacteriome and suggest consequences for human and animal health. Gut bacteriome comparisons across different environments diverge in their results, showing no generalizable patterns linking habitat and dietary degradation with bacterial diversity. The challenge in drawing general conclusions from such studies lies in the broad terms describing diverse habitats (“wild”, “captive”, “pristine”). We conducted 16S ribosomal RNA gene sequencing to characterize intestinal microbiota of free-ranging sympatric chimpanzees and gorillas in southeastern Cameroon and sympatric chimpanzees and gorillas in a European zoo. We conducted participant-observation and semi-structured interviews among people living near these great apes to understand better their feeding habits and habitats. Unexpectedly, bacterial diversity (ASV, Faith PD and Shannon) was higher among zoo gorillas than among those in the Cameroonian forest, but zoo and Cameroonian chimpanzees showed no difference. Phylogeny was a strong driver of species-specific microbial composition. Surprisingly, zoo gorilla microbiota more closely resembled that of zoo chimpanzees than of Cameroonian gorillas. Zoo living conditions and dietary similarities may explain these results. We encourage multidisciplinary approach integrating environmental sampling and anthropological evaluation to characterize better diverse environmental conditions of such investigations.

Applying modern coexistence theory to priority effects

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1803122116 ◽

2019 ◽

Vol 116 (13) ◽

pp. 6205-6210 ◽

Cited By ~ 18

Author(s):

Tess Nahanni Grainger ◽

Andrew D. Letten ◽

Benjamin Gilbert ◽

Tadashi Fukami

Keyword(s):

Growth Rates ◽

Competitive Exclusion ◽

Abiotic Factors ◽

Priority Effects ◽

Competitive Interactions ◽

Competing Species ◽

Coexistence Theory ◽

Dependent Growth ◽

Established Population ◽

Positive Frequency

Modern coexistence theory is increasingly used to explain how differences between competing species lead to coexistence versus competitive exclusion. Although research testing this theory has focused on deterministic cases of competitive exclusion, in which the same species always wins, mounting evidence suggests that competitive exclusion is often historically contingent, such that whichever species happens to arrive first excludes the other. Coexistence theory predicts that historically contingent exclusion, known as priority effects, will occur when large destabilizing differences (positive frequency-dependent growth rates of competitors), combined with small fitness differences (differences in competitors’ intrinsic growth rates and sensitivity to competition), create conditions under which neither species can invade an established population of its competitor. Here we extend the empirical application of modern coexistence theory to determine the conditions that promote priority effects. We conducted pairwise invasion tests with four strains of nectar-colonizing yeasts to determine how the destabilizing and fitness differences that drive priority effects are altered by two abiotic factors characterizing the nectar environment: sugar concentration and pH. We found that higher sugar concentrations increased the likelihood of priority effects by reducing fitness differences between competing species. In contrast, higher pH did not change the likelihood of priority effects, but instead made competition more neutral by bringing both fitness differences and destabilizing differences closer to zero. This study demonstrates how the empirical partitioning of priority effects into fitness and destabilizing components can elucidate the pathways through which environmental conditions shape competitive interactions.

Spatial variation in giraffe demography: a test of 2 paradigms

Journal of Mammalogy ◽

10.1093/jmammal/gyw086 ◽

2016 ◽

Vol 97 (4) ◽

pp. 1015-1025 ◽

Cited By ~ 18

Author(s):

Derek E. Lee ◽

Monica L. Bond ◽

Bernard M. Kissui ◽

Yustina A. Kiwango ◽

Douglas T. Bolger

Keyword(s):

Population Growth ◽

Spatial Variation ◽

Adult Female ◽

Vital Rate ◽

Adult Survival ◽

Continental Scale ◽

Demographic Rates ◽

Adult Females ◽

Calf Survival ◽

Female Survival

Abstract Examination of spatial variation in demography among or within populations of the same species is a topic of growing interest in ecology. We examined whether spatial variation in demography of a tropical megaherbivore followed the “temporal paradigm” or the “adult survival paradigm” of ungulate population dynamics formulated from temperate-zone studies. We quantified spatial variation in demographic rates for giraffes (Giraffa camelopardalis) at regional and continental scales. Regionally, we used photographic capture-mark-recapture data from 860 adult females and 449 calves to estimate adult female survival, calf survival, and reproduction at 5 sites in the Tarangire ecosystem of Tanzania. We examined potential mechanisms for spatial variation in regional demographic rates. At the continental scale, we synthesized demographic estimates from published studies across the range of the species. We created matrix population models for all sites at both scales and used prospective and retrospective analyses to determine which vital rate was most important to variation in population growth rate. Spatial variability of demographic parameters at the continental scale was in agreement with the temporal paradigm of low variability in adult survival and more highly variable reproduction and calf survival. In contrast, at the regional scale, adult female survival had higher spatial variation, in agreement with the adult survival paradigm. At both scales, variation in adult female survival made the greatest contribution to variation in local population growth rates. Our work documented contrasting patterns of spatial variation in demographic rates of giraffes at 2 spatial scales, but at both scales, we found the same vital rate was most important. We also found anthropogenic impacts on adult females are the most likely mechanism of regional population trajectories.

Extreme climatic events in relation to global change and their impact on life histories

Current Zoology ◽

10.1093/czoolo/57.3.375 ◽

2011 ◽

Vol 57 (3) ◽

pp. 375-389 ◽

Cited By ~ 58

Author(s):

Juan Moreno ◽

Anders Pape Møller

Keyword(s):

Life Histories ◽

Reproductive Effort ◽

Weather Conditions ◽

Extreme Weather ◽

Reproductive Failure ◽

Adult Survival ◽

Extreme Climatic Events ◽

Empirical Tests ◽

Living Organisms

Abstract Extreme weather conditions occur at an increasing rate as evidenced by higher frequency of hurricanes and more extreme precipitation and temperature anomalies. Such extreme environmental conditions will have important implications for all living organisms through greater frequency of reproductive failure and reduced adult survival. We review examples of reproductive failure and reduced survival related to extreme weather conditions. Phenotypic plasticity may not be sufficient to allow adaptation to extreme weather for many animals. Theory predicts reduced reproductive effort as a response to increased stochasticity. We predict that patterns of natural selection will change towards truncation selection as environmental conditions become more extreme. Such changes in patterns of selection may facilitate adaptation to extreme events. However, effects of selection on reproductive effort are difficult to detect. We present a number of predictions for the effects of extreme weather conditions in need of empirical tests. Finally, we suggest a number of empirical reviews that could improve our ability to judge the effects of extreme environmental conditions on life history.

The Role of Chloroplast Membrane Lipid Metabolism in Plant Environmental Responses

Cells ◽

10.3390/cells10030706 ◽

2021 ◽

Vol 10 (3) ◽

pp. 706

Author(s):

Ron Cook ◽

Josselin Lupette ◽

Christoph Benning

Keyword(s):

Environmental Changes ◽

Photosynthetic Apparatus ◽

Life Forms ◽

Membrane Lipid ◽

Chloroplast Membrane ◽

Class Composition ◽

Environmental Responses

Plants are nonmotile life forms that are constantly exposed to changing environmental conditions during the course of their life cycle. Fluctuations in environmental conditions can be drastic during both day–night and seasonal cycles, as well as in the long term as the climate changes. Plants are naturally adapted to face these environmental challenges, and it has become increasingly apparent that membranes and their lipid composition are an important component of this adaptive response. Plants can remodel their membranes to change the abundance of different lipid classes, and they can release fatty acids that give rise to signaling compounds in response to environmental cues. Chloroplasts harbor the photosynthetic apparatus of plants embedded into one of the most extensive membrane systems found in nature. In part one of this review, we focus on changes in chloroplast membrane lipid class composition in response to environmental changes, and in part two, we will detail chloroplast lipid-derived signals.