Environmental proteomics, biodiversity statistics and food-web structure

Gotelli, Nicholas J.; Ellison, Aaron M.; Ballif, Bryan A.

doi:10.1016/j.tree.2012.03.001

Cited by 29 publications

(20 citation statements)

References 68 publications

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“…Future work with this system will involve the identification of biologically based early-warning indicators of tipping points. We hypothesize that such biomarkers, including genomic and proteomic markers derived from microbial activity (37), can provide more lead time for intervention than measurements of traditional environmental variables such as [O 2 ], which may be easier to measure but are themselves driven by underlying biological processes.…”

Section: Discussionmentioning

confidence: 99%

Organic-matter loading determines regime shifts and alternative states in an aquatic ecosystem

Sirota

Baiser

Gotelli

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Slow changes in underlying state variables can lead to "tipping points," rapid transitions between alternative states ("regime shifts") in a wide range of complex systems. Tipping points and regime shifts routinely are documented retrospectively in long time series of observational data. Experimental induction of tipping points and regime shifts is rare, but could lead to new methods for detecting impending tipping points and forestalling regime shifts. By using controlled additions of detrital organic matter (dried, ground arthropod prey), we experimentally induced a shift from aerobic to anaerobic states in a miniature aquatic ecosystem: the self-contained pools that form in leaves of the carnivorous northern pitcher plant, Sarracenia purpurea. In unfed controls, the concentration of dissolved oxygen ([O 2 ]) in all replicates exhibited regular diurnal cycles associated with daytime photosynthesis and nocturnal plant respiration. In low preyaddition treatments, the regular diurnal cycles of [O 2 ] were disrupted, but a regime shift was not detected. In high prey-addition treatments, the variance of the [O 2 ] time series increased until the system tipped from an aerobic to an anaerobic state. In these treatments, replicate [O 2 ] time series predictably crossed a tipping point at ∼45 h as [O 2 ] was decoupled from diurnal cycles of photosynthesis and respiration. Increasing organic-matter loading led to predictable changes in [O 2 ] dynamics, with high loading consistently driving the system past a welldefined tipping point. The Sarracenia microecosystem functions as a tractable experimental system in which to explore the forecasting and management of tipping points and alternative regimes.

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Section: Discussionmentioning

confidence: 99%

Organic-matter loading determines regime shifts and alternative states in an aquatic ecosystem

Sirota

Baiser

Gotelli

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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“…In early studies on rarefaction, the original null hypothesis was that species richness in a small collection (a subsample of a specified size) could be viewed as a random subset of a larger collection (the reference sample; Simberloff 1979). However, the null hypothesis that ecologists usually want to ask is whether two or more reference samples (or subsamples of them) could be viewed as random draws from a single assemblage (Gotelli and Colwell 2011). This comparison is more challenging because it requires some estimate of the unconditional variance associated with sampling from the true assemblage (Colwell et al 2004), rather than just the conditional variance associated with subsampling from the largest sample in the collection.…”

Section: Ecological Null Hypothesismentioning

confidence: 99%

Ecological and biogeographic null hypotheses for comparing rarefaction curves

Cayuela

Gotelli

Colwell

2015

Ecological Monographs

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The statistical framework of rarefaction curves and asymptotic estimators allows for an effective standardization of biodiversity measures. However, most statistical analyses still consist of point comparisons of diversity estimators for a particular sampling level. We introduce new randomization methods that incorporate sampling variability encompassing the entire length of the rarefaction curve and allow for statistical comparison of i !2 individual-based, sample-based, or coverage-based rarefaction curves. These methods distinguish between two distinct null hypotheses: the ecological null hypothesis (H 0eco ) and the biogeographical null hypothesis (H 0biog ).H 0eco states that the i samples were drawn from a single assemblage, and any differences among them in species richness, composition, or relative abundance reflect only sampling effects. H 0biog states that the i samples were drawn from assemblages that differ in their species composition but share similar species richness and species abundance distributions. To test H 0eco , we created a composite rarefaction curve by summing the abundances of all species from the i samples. We then calculated a test statistic Z eco , the (cumulative) summed areas of difference between each of the i individual curves and the composite curve. For H 0biog , the test statistic Z biog was calculated by summing the area of difference between all possible pairs of the i individual curves. Bootstrap sampling from the composite curve (H 0eco ) or random sampling from different simulated assemblages using alternative abundance distributions (H 0biog ) was used to create the null distribution of Z, and to provide a frequentist test of Z j H 0 . Rejection of H 0eco does not pinpoint whether the samples differ in species richness, species composition, and/or relative abundance.In benchmark comparisons, both tests performed satisfactorily against artificial data sets randomly drawn from a single assemblage (low Type I error). In benchmark comparisons with different species abundance distributions and richness, the tests had adequate power to detect differences among curves (low Type II error), although power diminished at small sample sizes and for small differences among underlying species rank abundances.

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“…Nutrients, mainly lipids, are involved in many vital functions of aquatic individuals (Arts et al, 2001;Gotelli et al, 2012). Since some of them can only be obtained from food and therefore referred to as 'essential nutrients' they have proven to be useful trophic markers (Kelly and Scheibling, 2012).…”

Section: Introductionmentioning

confidence: 99%

Biochemical and toxicological effects of organic (herbicide Primextra® Gold TZ) and inorganic (copper) compounds on zooplankton and phytoplankton species

et al. 2016

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a b s t r a c tIn Europe, mainly in the Mediterranean region, an intensive usage of pesticides was recorded during the past 30 years. According to information from agricultural cooperatives of the Mondego valley (Figueira da Foz, Portugal), Primextra ® Gold TZ is the most used herbicide in corn crop fields and one of the 20 best-selling herbicides in Portugal. Copper is mainly used in pesticide formulations. This study aims to determine the ecotoxicological and biochemical (namely fatty acid profiles) effects of the herbicide Primextra ® Gold TZ and the metal copper on marine plankton. The organisms used in this study are three planktonic species: the marine diatom Thalassiosira weissflogii, the estuarine copepod Acartia tonsa and nauplii of the marine brine shrimp Artemia franciscana. Fatty acids (FAs) are one of the most important molecules transferred across the plant-animal interface in aquatic food webs and can be used as good indicators of stress. The conducted lab incubations show that T. weissflogii is the most sensitive species to the herbicide followed by A. tonsa (EC 50 = 0.0078 mg/L and EC 50 = 0.925 mg/L, respectively), whereas the copepod was the most sensitive species to the metal followed by T. weissflogii (EC 50 = 0.234 mg/L and EC 50 = 0.383 mg/L, respectively). A. franciscana was the most tolerant organism both to the herbicide and to the metal (EC 50 = 20.35 mg/L and EC 50 = 18.93 mg/L, respectively). Changes in the FA profiles of primary producer and primary consumers were observed, with the increase of saturated FA and decrease of unsaturated FA contents, especially of highly unsaturated FAs that can be obtained mainly from food and therefore are referred to as 'essential FA'. The study suggests that discharges of Primextra ® Gold TZ or other pesticides mainly composed by copper may be a threat to plankton populations causing changes in the FA contents and thus in their nutritive value, with severe repercussions for higher trophic levels and thus the entire food web.

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Environmental proteomics, biodiversity statistics and food-web structure

Cited by 29 publications

References 68 publications

Organic-matter loading determines regime shifts and alternative states in an aquatic ecosystem

Organic-matter loading determines regime shifts and alternative states in an aquatic ecosystem

Ecological and biogeographic null hypotheses for comparing rarefaction curves

Biochemical and toxicological effects of organic (herbicide Primextra® Gold TZ) and inorganic (copper) compounds on zooplankton and phytoplankton species

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