@article{ReegStriglJeltsch2022, author = {Reeg, Jette and Strigl, Lea and Jeltsch, Florian}, title = {Agricultural buffer zone thresholds to safeguard functional bee diversity}, series = {Ecology and Evolution}, volume = {12}, journal = {Ecology and Evolution}, edition = {3}, publisher = {Wiley Online Library}, address = {Hoboken, New Jersey, USA}, issn = {2045-7758}, doi = {10.1002/ece3.8748}, pages = {1 -- 17}, year = {2022}, abstract = {Wild bee species are important pollinators in agricultural landscapes. However, population decline was reported over the last decades and is still ongoing. While agricultural intensification is a major driver of the rapid loss of pollinating species, transition zones between arable fields and forest or grassland patches, i.e., agricultural buffer zones, are frequently mentioned as suitable mitigation measures to support wild bee populations and other pollinator species. Despite the reported general positive effect, it remains unclear which amount of buffer zones is needed to ensure a sustainable and permanent impact for enhancing bee diversity and abundance. To address this question at a pollinator community level, we implemented a process-based, spatially explicit simulation model of functional bee diversity dynamics in an agricultural landscape. More specifically, we introduced a variable amount of agricultural buffer zones (ABZs) at the transition of arable to grassland, or arable to forest patches to analyze the impact on bee functional diversity and functional richness. We focused our study on solitary bees in a typical agricultural area in the Northeast of Germany. Our results showed positive effects with at least 25\% of virtually implemented agricultural buffer zones. However, higher amounts of ABZs of at least 75\% should be considered to ensure a sufficient increase in Shannon diversity and decrease in quasi-extinction risks. These high amounts of ABZs represent effective conservation measures to safeguard the stability of pollination services provided by solitary bee species. As the model structure can be easily adapted to other mobile species in agricultural landscapes, our community approach offers the chance to compare the effectiveness of conservation measures also for other pollinator communities in future.}, language = {en} } @article{MendesFerreiraDammhahnEccard2022, author = {Mendes Ferreira, Clara and Dammhahn, Melanie and Eccard, Jana}, title = {Forager-mediated cascading effects on food resource species diversity}, series = {Ecology and Evolution}, volume = {12}, journal = {Ecology and Evolution}, number = {11}, publisher = {John Wiley \& Sons}, issn = {2045-7758}, doi = {10.1002/ece3.9523}, pages = {13}, year = {2022}, abstract = {Perceived predation risk varies in space and time. Foraging in this landscape of fear alters forager-resource interactions via cascading nonconsumptive effects. Estimating these indirect effects is difficult in natural systems. Here, we applied a novel measure to quantify the diversity at giving-up density that allows to test how spatial variation in perceived predation risk modifies the diversity of multispecies resources at local and regional spatial levels. Furthermore, we evaluated whether the nonconsumptive effects on resource species diversity can be explained by the preferences of foragers for specific functional traits and by the forager species richness. We exposed rodents of a natural community to artificial food patches, each containing an initial multispecies resource community of eight species (10 items each) mixed in sand. We sampled 35 landscapes, each containing seven patches in a spatial array, to disentangle effects at local (patch) and landscape levels. We used vegetation height as a proxy for perceived predation risk. After a period of three nights, we counted how many and which resource species were left in each patch to measure giving-up density and resource diversity at the local level (alpha diversity) and the regional level (gamma diversity and beta diversity). Furthermore, we used wildlife cameras to identify foragers and assess their species richness. With increasing vegetation height, i.e., decreasing perceived predation risk, giving-up density, and local alpha and regional gamma diversity decreased, and patches became less similar within a landscape (beta diversity increased). Foragers consumed more of the bigger and most caloric resources. The higher the forager species richness, the lower the giving-up density, and alpha and gamma diversity. Overall, spatial variation of perceived predation risk of foragers had measurable cascading effects on local and regional resource species biodiversity, independent of the forager species. Thus, nonconsumptive predation effects modify forager-resource interactions and might act as an equalizing mechanism for species coexistence.}, language = {en} } @article{EccardMendesFerreiraPeredoArceetal.2022, author = {Eccard, Jana and Mendes Ferreira, Clara and Peredo Arce, Andres and Dammhahn, Melanie}, title = {Top-down effects of foraging decisions on local, landscape and regional biodiversity of resources (DivGUD)}, series = {Ecology letters}, volume = {25}, journal = {Ecology letters}, number = {1}, publisher = {Wiley-Blackwell}, address = {Oxford [u.a.]}, issn = {1461-0248}, doi = {10.1111/ele.13901}, pages = {3 -- 16}, year = {2022}, abstract = {Foraging by consumers acts as a biotic filtering mechanism for biodiversity at the trophic level of resources. Variation in foraging behaviour has cascading effects on abundance, diversity, and functional trait composition of the community of resource species. Here we propose diversity at giving-up density (DivGUD), i.e. when foragers quit exploiting a patch, as a novel concept and simple measure quantifying cascading effects at multiple spatial scales. In experimental landscapes with an assemblage of plant seeds, patch residency of wild rodents decreased local alpha-DivGUD (via elevated mortality of species with large seeds) and regional gamma-DivGUD, while dissimilarity among patches in a landscape (beta-DivGUD) increased. By linking theories of adaptive foraging behaviour with community ecology, DivGUD allows to investigate cascading indirect predation effects, e.g. the ecology-of-fear framework, feedbacks between functional trait composition of resource species and consumer communities, and effects of inter-individual differences among foragers on the biodiversity of resource communities.}, language = {en} } @article{KerneckerFienitzNendeletal.2022, author = {Kernecker, Maria and Fienitz, Meike and Nendel, Claas and Paetzig, Marlene and Walzl, Karin Pirhofer and Raatz, Larissa and Schmidt, Martin and Wulf, Monika and Zscheischler, Jana}, title = {Transition zones across agricultural field boundaries for integrated landscape research and management of biodiversity and yields}, series = {Ecological solutions and evidence}, volume = {3}, journal = {Ecological solutions and evidence}, number = {1}, publisher = {Wiley}, address = {Hoboken}, issn = {2688-8319}, doi = {10.1002/2688-8319.12122}, pages = {7}, year = {2022}, abstract = {Biodiversity conservation and agricultural production have been largely framed as separate goals for landscapes in the discourse on land use. Although there is an increasing tendency to move away from this dichotomy in theory, the tendency is perpetuated by the spatially explicit approaches used in research and management practice. Transition zones (TZ) have previously been defined as areas where two adjacent fields or patches interact, and so they occur abundantly throughout agricultural landscapes. Biodiversity patterns in TZ have been extensively studied, but their relationship to yield patterns and social-ecological dimensions has been largely neglected. Focusing on European, temperate agricultural landscapes, we outline three areas of research and management that together demonstrate how TZ might be used to facilitate an integrated landscape approach: (i) plant and animal species' use and response to boundaries and the resulting effects on yield, for a deeper understanding of how landscape structure shapes quantity and quality of TZ; (ii) local knowledge on field or patch-level management and its interactions with biodiversity and yield in TZ, and (iii) conflict prevention and collaborative management across land-use boundaries.}, language = {en} } @article{MarciszJasseyKosakyanetal.2020, author = {Marcisz, Katarzyna and Jassey, Vincent E. J. and Kosakyan, Anush and Krashevska, Valentyna and Lahr, Daniel J. G. and Lara, Enrique and Lamentowicz, Lukasz and Lamentowicz, Mariusz and Macumber, Andrew and Mazei, Yuri and Mitchell, Edward A. D. and Nasser, Nawaf A. and Patterson, R. Timothy and Roe, Helen M. and Singer, David and Tsyganov, Andrey N. and Fournier, Bertrand}, title = {Testate amoeba functional traits and their use in paleoecology}, series = {Frontiers in Ecology and Evolution}, volume = {8}, journal = {Frontiers in Ecology and Evolution}, publisher = {Frontiers Media}, address = {Lausanne}, issn = {2296-701X}, doi = {10.3389/fevo.2020.575966}, pages = {28}, year = {2020}, abstract = {This review provides a synthesis of current knowledge on the morphological and functional traits of testate amoebae, a polyphyletic group of protists commonly used as proxies of past hydrological changes in paleoecological investigations from peatland, lake sediment and soil archives. A trait-based approach to understanding testate amoebae ecology and paleoecology has gained in popularity in recent years, with research showing that morphological characteristics provide complementary information to the commonly used environmental inferences based on testate amoeba (morpho-)species data. We provide a broad overview of testate amoeba morphological and functional traits and trait-environment relationships in the context of ecology, evolution, genetics, biogeography, and paleoecology. As examples we report upon previous ecological and paleoecological studies that used trait-based approaches, and describe key testate amoebae traits that can be used to improve the interpretation of environmental studies. We also highlight knowledge gaps and speculate on potential future directions for the application of trait-based approaches in testate amoeba research.}, language = {en} } @article{EhrlichGaedke2020, author = {Ehrlich, Elias and Gaedke, Ursula}, title = {Coupled changes in traits and biomasses cascading through a tritrophic plankton food web}, series = {Limnology and oceanography}, volume = {65}, journal = {Limnology and oceanography}, number = {10}, publisher = {Wiley}, address = {Hoboken}, issn = {0024-3590}, doi = {10.1002/lno.11466}, pages = {2502 -- 2514}, year = {2020}, abstract = {Trait-based approaches have broadened our understanding of how the composition of ecological communities responds to environmental drivers. This research has mainly focussed on abiotic factors and competition determining the community trait distribution, while effects of trophic interactions on trait dynamics, if considered at all, have been studied for two trophic levels at maximum. However, natural food webs are typically at least tritrophic. This enables indirect interactions of traits and biomasses among multiple trophic levels leading to underexplored effects on food web dynamics. Here, we demonstrate the occurrence of mutual trait adjustment among three trophic levels in a natural plankton food web (Lake Constance) and in a corresponding mathematical model. We found highly recurrent seasonal biomass and trait dynamics, where herbivorous zooplankton increased its size, and thus its ability to counter phytoplankton defense, before phytoplankton defense actually increased. This is contrary to predictions from bitrophic systems where counter-defense of the consumer is a reaction to prey defense. In contrast, counter-defense of carnivores by size adjustment followed the defense of herbivores as expected. By combining observations and model simulations, we show how the reversed trait dynamics at the two lower trophic levels result from a "trophic biomass-trait cascade" driven by the carnivores. Trait adjustment between two trophic levels can therefore be altered by biomass or trait changes of adjacent trophic levels. Hence, analyses of only pairwise trait adjustment can be misleading in natural food webs, while multitrophic trait-based approaches capture indirect biomass-trait interactions among multiple trophic levels.}, language = {en} } @article{EhrlichKathGaedke2020, author = {Ehrlich, Elias and Kath, Nadja Jeanette and Gaedke, Ursula}, title = {The shape of a defense-growth trade-off governs seasonal trait dynamics in natural phytoplankton}, series = {The ISME journal}, volume = {14}, journal = {The ISME journal}, number = {6}, publisher = {Nature Publishing Group}, address = {London}, issn = {1751-7362}, doi = {10.1038/s41396-020-0619-1}, pages = {1451 -- 1462}, year = {2020}, abstract = {Theory predicts that trade-offs, quantifying costs of functional trait adjustments, crucially affect community trait adaptation to altered environmental conditions, but empirical verification is scarce. We evaluated trait dynamics (antipredator defense, maximum growth rate, and phosphate affinity) of a lake phytoplankton community in a seasonally changing environment, using literature trait data and 21 years of species-resolved high-frequency biomass measurements. The trait data indicated a concave defense-growth trade-off, promoting fast-growing species with intermediate defense. With seasonally increasing grazing pressure, the community shifted toward higher defense levels at the cost of lower growth rates along the trade-off curve, while phosphate affinity explained some deviations from it. We discuss how low fitness differences of species, inferred from model simulations, in concert with stabilizing mechanisms, e.g., arising from further trait dimensions, may lead to the observed phytoplankton diversity. In conclusion, quantifying trade-offs is key for predictions of community trait adaptation and biodiversity under environmental change.}, language = {en} } @article{WeithoffBeisner2019, author = {Weithoff, Guntram and Beisner, Beatrix E.}, title = {Measures and Approaches in Trait-Based Phytoplankton Community Ecology}, series = {Frontiers in Marine Science}, volume = {6}, journal = {Frontiers in Marine Science}, publisher = {Frontiers Media}, address = {Lausanne}, issn = {2296-7745}, doi = {10.3389/fmars.2019.00040}, pages = {11}, year = {2019}, abstract = {Trait-based approaches to investigate (short- and long-term) phytoplankton dynamics and community assembly have become increasingly popular in freshwater and marine science. Although the nature of the pelagic habitat and the main phytoplankton taxa and ecology are relatively similar in both marine and freshwater systems, the lines of research have evolved, at least in part, separately. We compare and contrast the approaches adopted in marine and freshwater ecosystems with respect to phytoplankton functional traits. We note differences in study goals relating to functional trait use that assess community assembly and those that relate to ecosystem processes and biogeochemical cycling that affect the type of characteristics assigned as traits to phytoplankton taxa. Specific phytoplankton traits relevant for ecological function are examined in relation to herbivory, amplitude of environmental change and spatial and temporal scales of study. Major differences are identified, including the shorter time scale for regular environmental change in freshwater ecosystems compared to that in the open oceans as well as the type of sampling done by researchers based on site-accessibility. Overall, we encourage researchers to better motivate why they apply trait-based analyses to their studies and to make use of process-driven approaches, which are more common in marine studies. We further propose fully comparative trait studies conducted along the habitat gradient spanning freshwater to brackish to marine systems, or along geographic gradients. Such studies will benefit from the combined strength of both fields.}, language = {en} } @article{EhrlichBecksGaedke2017, author = {Ehrlich, Elias and Becks, Lutz and Gaedke, Ursula}, title = {Trait-fitness relationships determine how trade-off shapes affect species coexistence}, series = {Ecology : a publication of the Ecological Society of America}, volume = {98}, journal = {Ecology : a publication of the Ecological Society of America}, publisher = {Wiley}, address = {Hoboken}, issn = {0012-9658}, doi = {10.1002/ecy.2047}, pages = {3188 -- 3198}, year = {2017}, abstract = {Trade-offs between functional traits are ubiquitous in nature and can promote species coexistence depending on their shape. Classic theory predicts that convex trade-offs facilitate coexistence of specialized species with extreme trait values (extreme species) while concave trade-offs promote species with intermediate trait values (intermediate species). We show here that this prediction becomes insufficient when the traits translate non-linearly into fitness which frequently occurs in nature, e.g., an increasing length of spines reduces grazing losses only up to a certain threshold resulting in a saturating or sigmoid trait-fitness function. We present a novel, general approach to evaluate the effect of different trade-off shapes on species coexistence. We compare the trade-off curve to the invasion boundary of an intermediate species invading the two extreme species. At this boundary, the invasion fitness is zero. Thus, it separates trait combinations where invasion is or is not possible. The invasion boundary is calculated based on measurable trait-fitness relationships. If at least one of these relationships is not linear, the invasion boundary becomes non-linear, implying that convex and concave trade-offs not necessarily lead to different coexistence patterns. Therefore, we suggest a new ecological classification of trade-offs into extreme-favoring and intermediate-favoring which differs from a purely mathematical description of their shape. We apply our approach to a well-established model of an empirical predator-prey system with competing prey types facing a trade-off between edibility and half-saturation constant for nutrient uptake. We show that the survival of the intermediate prey depends on the convexity of the trade-off. Overall, our approach provides a general tool to make a priori predictions on the outcome of competition among species facing a common trade-off in dependence of the shape of the trade-off and the shape of the trait-fitness relationships.}, language = {en} } @article{BoliusWiednerWeithoff2017, author = {Bolius, Sarah and Wiedner, Claudia and Weithoff, Guntram}, title = {High local trait variability in a globally invasive cyanobacterium}, series = {Freshwater biology}, volume = {62}, journal = {Freshwater biology}, publisher = {Wiley}, address = {Hoboken}, issn = {0046-5070}, doi = {10.1111/fwb.13028}, pages = {1879 -- 1890}, year = {2017}, abstract = {1. During the last couple of decades, invasive species have become a worldwide problem in many freshwater systems. Besides higher plants and animals, microbes, in particular the potentially toxic cyanobacterium Cylindrospermopsis raciborskii, has attracted increasing attention, due to its spread towards temperate zones of the northern and southern hemisphere. A number of advantageous functional traits and a high intraspecific plasticity have been suggested to explain its invasion success. 2. The aim of this study was to examine intraspecific functional trait variability in 12 different isolates of C.raciborskii originating from different lakes in an invaded region in Northeast Germany. We measured growth rate, C:N:P ratios, chlorophyll-a content and the abundance of heterocysts under nutrient-replete and phosphorus-limited conditions. Moreover, the isolate-specific morphology and grazing losses by an herbivorous rotifer, as a top-down force, were studied. 3. DNA fingerprinting revealed that all isolates were genetically different. C.raciborskii exhibited a large variability in all measured traits among isolates. The C:P, N:P and Chl-a:C ratios differed by a factor of two or more. The trait variability among isolates was higher under nutrient-replete conditions, except for the C:P ratio, which varied most during phosphorus limitation. The susceptibility to grazing, calculated as maximum ingestion rates of the rotifer Brachionus calyciflorus on C.raciborskii, varied most among isolates, but was not related to any of the measured physiological or morphological traits, i.e. no trade-off was found. 4. Ecological and genetic clustering did not match, indicating that the genetic relationship based on DNA fingerprinting did not cover ecological differences. 5. Our results show a high trait variability within locally occurring and partly co-occurring C.raciborskii isolates. No overall trade-offs between the measured functional traits were found. This demonstrates the ecological relevance of linking multiple traits, e.g. competitive and consumptive. Furthermore, this study emphasises the importance of analysing more than one strain of a species, as different strains show different trait values potentially relevant for their invasibility and the field of general trait-based ecology.}, language = {en} }