Different Levels Of Ecological Organization Research Articles

Stable isotope spatial patterns for the Southwest Atlantic Ocean towards polar waters

Mapping stable isotope gradients (isoscapes) has become a powerful tool to understand and forecast the status and variability of marine ecosystems at different levels of ecological organization. To differentiate five marine areas from the Southwest Atlantic Ocean towards oceanic and polar waters, a key foraging area for many marine consumers, we built isoscapes at different spatial scales using carbon (δ13C) and nitrogen (δ15N) isotope values of phytoplankton, zooplankton and particulate organic matter in sediment. We analyzed the isotopic variability between marine areas in relation with oceanographic parameters (e.g. temperature, salinity) and geographical sampling site data (e.g. latitude, longitude). We collected samples during 6 oceanographic surveys conducted in spring and autumn between 2014 and 2019 at the Beagle Channel, the Atlantic coast of Tierra del Fuego and Burdwood Bank. We included also published isotopic data of zooplankton from two other oceanic areas (the Polar Frontal Zone and Polar Antarctic Peninsula waters) to construct large-scale isoscapes. We found that the marine areas analyzed have substantially different δ13C and δ15N baselines; some differences exist between spring and autumn but the general pattern of isotopic variability remains similar. Combining different biological components and spatial scale analysis, isotopic variability was found to be related to variables such as seawater temperature, depth, chlorophyll and nutrients. The generated data will enhance the efficacy of isoscapes in long-term monitoring initiatives that documents alterations in attributes and features across marine expanses. This is particularly pertinent to areas under legal protection, such as the oceanic Marine Protected Areas (MPAs) established in Argentine waters.

BatFly: A database of Neotropical bat-fly interactions.

Global changes have increased the risk of emerging infectious diseases, which can be prevented or mitigated by studying host-parasite interactions, among other measures. Bats and their ectoparasitic flies of the families Streblidae and Nycteribiidae are an excellent study model but, so far, our knowledge has been restricted to fragmented records at a local scale. To help boost research, we assembled a data set of bat-fly interactions from 174 studies published between 1904 and 2022 plus three original data sets. Altogether, these studies were carried out at 650 sites in the Neotropics, mainly distributed in Mexico, Brazil, Argentina, southern USA, and Colombia, among other countries. In total, our data set contains 3984 interaction records between 237 bat species and 255 fly species. The bat species with the largest number of recorded interactions were Carollia perspicillata (357), Artibeus jamaicensis (263), and Artibeus lituratus (228). The fly species with the largest number of recorded interactions were Trichobius joblingi (256), Megistopoda aranea (235), and Megistopoda proxima (215). The interaction data were extracted, filtered, taxonomically harmonized, and made available in a tidy format together with linked data on bat population, fly population, study reference, sampling methods and geographic information from the study sites. This interconnected structure enables the expansion of information for each interaction record, encompassing where and how each interaction occurred, as well as the number of bats and flies involved. We expect BatFly to open new avenues for research focused on different levels of ecological organization and spatial scales. It will help consolidate knowledge about ecological specialization, resource distribution, pathogen transmission, and the drivers of parasite prevalence over a broad spatial range. It may also help to answer key questions such as: Are there differences in fly prevalence or mean infestation across Neotropical ecoregions? What ecological drivers explain those differences? How do specialization patterns vary among fly species in the Neotropics? Furthermore, we expect BatFly to inspire research aimed at understanding how climate and land-use changes may impact host-parasite interactions and disease outbreaks. This kind of research may help us reach Sustainable Development Goal 3, Good Health and Wellbeing, outlined by the United Nations. The data are released under a Creative Commons Attribution 4.0 International License.

From meta-system theory to the sustainable management of rivers in the Anthropocene.

Regional‐scale ecological processes, such as the spatial flows of material, energy, and organisms, are fundamental for maintaining biodiversity and ecosystem functioning in river networks. Yet these processes remain largely overlooked in most river management practices and underlying policies. Here, we propose adoption of a meta‐system approach, where regional processes acting at different levels of ecological organization – populations, communities, and ecosystems – are integrated into conventional river conservation, restoration, and biomonitoring. We also describe a series of measurements and indicators that could be assimilated into the implementation of relevant biodiversity and environmental policies. Finally, we highlight the need for alternative management strategies that can guide practitioners toward applying recent advances in ecology to preserve and restore river ecosystems and the ecosystem services they provide, in the context of increasing alteration of river network connectivity worldwide.

Using phylogenetic information to impute missing functional trait values in ecological databases

Trait-based approaches offer complementary views to the classic taxonomic approach, which is a crucial step forward to unveil mechanisms of community assembly, species interactions, ecosystem functioning, and tackling important conservation issues. These approaches require an enormous sampling effort to provide complete trait datasets, consequently, missing data are very common. We evaluated the performance of the missForest algorithm, that uses the Random Forest method to impute species traits values using phylogenetic information. We simulated datasets with different sizes and proportions of missing data, different levels of trait conservatism, and trait correlation. We tested trait imputation using the missForest algorithm without phylogenetic information and adding the phylogenetic relationship among species, using phylogenetic eigenvector. Our results show that the level of phylogenetic signal in traits and the correlation among them are the main parameters that influence the measures of imputation error. The measures of errors are smaller when traits have higher levels of correlation and when traits are conserved in the phylogenetic tree. In general, the inclusion of phylogenetic vectors as predictors in the missForest algorithm improves the estimation of missing values. However, the importance of phylogenetic information to the imputation process depends on the proportion of missing entries, phylogenetic conservatism of traits, and the correlation among traits. The missForest algorithm seems to be a robust method for trait imputation, and it can be used to estimate missing traits without the exclusion of species. Thus, we expect to have contributed with a new step to guide methodological choices to impute entire databases of traits with the goal of decreasing uncertainties and bias in the interpretation of ecological patterns and processes at different levels of ecological organization.

Interplay of geomorphology and hydrology drives macroinvertebrate assemblage responses to hydropeaking

Hydropeaking leads to major anthropogenic disturbance of river networks worldwide. Flow variations imposed by hydropeaking may significantly affect macroinvertebrate assemblages within the river network. As such, the responses of macroinvertebrate assemblages to hydropeaking are expected to be complex and vary across spatial and temporal scales as well as ecological organization levels. To unpack this complexity, we assessed the interplay of geomorphic and hydrological variables as drivers of the responses of macroinvertebrate assemblages to hydropeaking. Specifically, we studied different levels of ecological organization of macroinvertebrate assemblages in two functional process zones (FPZs; Sub-Andean and Central Valley Gravel Dominated) subjected to different flow management in two Chilean Andean river networks. Hydropeaking caused significant reduction of macroinvertebrate abundances in both FPZs and at all ecological organization levels with the exception of one feeding guild (scrapers). Furthermore, the response of macroinvertebrate assemblage variance was stronger in the Central Valley Gravel Dominated FPZ. Both geomorphic and hydrological variables influenced macroinvertebrate assemblage responses. However, the effects of the principal geomorphic variables operated at valley (meso) spatial scale and the main hydrological variables operated at the sub-daily (micro) temporal scale. Therefore, to minimise the effects of hydropeaking on macroinvertebrate assemblages, flow management should consider reduction of sub-daily variability. Furthermore, placement of new barriers should take into account not only their position within the river network but also their effects downstream that strongly depend on characteristics of river valley.

Global trends and challenges in multimetric indices of biological condition

Abstract The use of multimetric indices (MMIs) of biological condition has been globally applied because they are practical tools that incorporate various biological metrics at different levels of ecological organization. However, the methods for developing and evaluating MMIs have been criticized. We reviewed the scientific literature to assess global processes for MMI creation and validation. We found a lack of common criteria for metric selection and determination of reference conditions, which hinders making comparable assessments across different programs and regions as well as for developing or refining future MMIs. We also present the ten metrics most commonly used in MMIs worldwide. Finally, we determined that differentiating natural variability from anthropogenic impacts is the major challenge in creating and applying MMIs. We offer our review to further the advancement and improvement of MMIs as standard bioassesment tools.

Understanding extinction debts: spatio–temporal scales, mechanisms and a roadmap for future research

Extinction debt refers to delayed species extinctions expected as a consequence of ecosystem perturbation. Quantifying such extinctions and investigating long‐term consequences of perturbations has proven challenging, because perturbations are not isolated and occur across various spatial and temporal scales, from local habitat losses to global warming. Additionally, the relative importance of eco‐evolutionary processes varies across scales, because levels of ecological organization, i.e. individuals, (meta)populations and (meta)communities, respond hierarchically to perturbations. To summarize our current knowledge of the scales and mechanisms influencing extinction debts, we reviewed recent empirical, theoretical and methodological studies addressing either the spatio–temporal scales of extinction debts or the eco‐evolutionary mechanisms delaying extinctions. Extinction debts were detected across a range of ecosystems and taxonomic groups, with estimates ranging from 9 to 90% of current species richness. The duration over which debts have been sustained varies from 5 to 570 yr, and projections of the total period required to settle a debt can extend to 1000 yr. Reported causes of delayed extinctions are 1) life‐history traits that prolong individual survival, and 2) population and metapopulation dynamics that maintain populations under deteriorated conditions. Other potential factors that may extend survival time such as microevolutionary dynamics, or delayed extinctions of interaction partners, have rarely been analyzed. Therefore, we propose a roadmap for future research with three key avenues: 1) the microevolutionary dynamics of extinction processes, 2) the disjunctive loss of interacting species and 3) the impact of multiple regimes of perturbation on the payment of debts. For their ability to integrate processes occurring at different levels of ecological organization, we highlight mechanistic simulation models as tools to address these knowledge gaps and to deepen our understanding of extinction dynamics.

Assessing the gap between conservation need and protection status for select rare ecosystems in Alaska

AbstractRare ecosystems support unique assemblages of flora and fauna within a small geographic area. As such, their conservation represents an effective method of biodiversity protection. The description, mapping, and assessment of rare ecosystems is a necessary and initial conservation action, yet this has not been completed for Alaska. Here, we provide the first comprehensive treatment of rare terrestrial ecosystems for the state. Thirty‐five rare systems, representing different levels of ecological organization and geographic scale, are presented. In addition, a gap analysis was conducted to evaluate the systems' current level of land management protection relative to their conservation need. Eleven of the mapped ecosystems are considered adequately protected, two are moderately protected, and 22 are less protected. Conservation ranks are incongruously aligned with land management protection levels such that the rarest systems are often not well protected and the less‐imperiled systems are often well protected. On the ecoregion scale, systems with arctic distributions are less protected than are those with boreal and maritime distributions. This rare ecosystem assessment complements species‐ and landscape‐scale conservation studies previously completed for Alaska. Collectively, the recommendations from these assessments provide a science‐based strategy for biological conservation in a vulnerable region of the world.

Interactions between ecological, evolutionary and environmental processes unveil complex dynamics of insular plant diversity

AbstractAimsUnderstanding how biodiversity emerges and how it varies in space and time requires integration of the underlying processes that affect biodiversity at different levels of ecological organization. We present BioGEEM (BioGeographical Eco‐Evolutionary Model), a spatially explicit model that integrates theories and processes understood to drive biodiversity dynamics. We investigated the necessary degree of mechanistic complexity by exploring simulation experiments to evaluate the relative roles of the underlying processes across spatio‐temporal scales and ecological levels (e.g. populations, species, communities).LocationHypothetical oceanic islands.MethodsBioGEEM is stochastic and grid‐based, and it integrates ecological (metabolic constraints, demography, dispersal and competition), evolutionary (mutation and speciation) and environmental (geo‐climatic dynamics) processes. Plants on oceanic islands served as a model system. We ran the simulations both with all processes on and with selected processes switched off to assess the role of each process from the emergent patterns.ResultsThe full model was able to generate patterns matching empirical evidence and theoretical expectations. Population sizes were largest on young islands, and species, particularly endemics, better filled their potential range on young and old islands due to limited area and reduced competition. Richness peaked at mid‐elevations. The proportion of endemics was highest in old, large and isolated environments within the islands. Species and trait richness showed unimodal temporal trends. Switching off selected processes led to several unrealistic patterns, including the evolution of super‐dominant species, extremely high richness and weakened spatial diversity gradients.Main conclusionsThe main predictions derived from BioGEEM are: Competition has cross‐scale effects on diversity. Hump‐shaped temporal dynamics can be obtained without speciation. Endemic species seem less susceptible to extinction than native non‐endemic species. Endemism reflects stronger geographical and environmental isolation. Finally, only the integration of all implemented processes generates realistic spatio‐temporal dynamics at population, species, community and assemblage levels.

Parasite and host elemental content and parasite effects on host nutrient excretion and metabolic rate.

Ecological stoichiometry uses the mass balance of elements to predict energy and elemental fluxes across different levels of ecological organization. A specific prediction of ecological stoichiometry is the growth rate hypothesis (GRH), which states that organisms with faster growth or reproductive rates will require higher phosphorus content for nucleic acid and protein synthesis. Although parasites are found ubiquitously throughout ecosystems, little is understood about how they affect nutrient imbalances in ecosystems. We (1) tested the GRH by determining the carbon (C), nitrogen (N), and phosphorus (P) content of parasitic trematodes and their intermediate host, the freshwater snail Elimia livescens, and (2) used this framework to determine the trematode effects on host nutrient excretion and metabolism. Snail and parasite tissues were analyzed for elemental content using a CHN analyzer and soluble reactive phosphorus (SRP) methods. Ammonium and SRP assays were used to estimate N and P excretion rates. A respirometer was used to calculate individual snail metabolism. Trematode tissues contained lower C:P and N:P (more P per unit C and N) than the snail tissues. Snail gonadal tissues more closely resembled the elemental content of parasite tissues, although P content was 13% higher in the gonad than the trematode tissues. Despite differences in elemental content, N and P excretion rates of snails were not affected by the presence of parasites. Parasitized snails maintained faster metabolic rates than nonparasitized snails. However, the species of parasite did not affect metabolic rate. Together, this elemental imbalance between parasite and host, and the altered metabolic rate of infected snails may lead to broader parasite effects in stream ecosystems.

Pattern and scale in latitude–production relationships for freshwater fishes

AbstractEmpirically understanding spatial variation in secondary production rates is central to ecology. Yet for most taxa, such patterns are rarely examined, especially at different levels of ecological organization (e.g., species‐ vs. community‐level patterns). We compiled data on biomass, production, and P/B rates of freshwater fish communities and species across latitudes and contrast patterns observed at the community level with those observed for species. At the community level, and at two distinct spatial scales (global vs. continental‐North American), negative or neutral relationships were apparent between biomass, production, and P/B with latitude; however, there was substantial scatter in these data. Yet at the species level in North America, production was often closely linked to latitude, but in the opposite direction: Many species showed improved production with latitude. Latitudinal increases in species‐level production rates were strongest for cool‐ and cold‐water species, and species rarely showed the opposite trend. Species‐level increases in production with latitude strengthened when production rates were normalized by the thermal opportunity for production, suggesting potential adaptations of individuals and populations to shorter growing seasons (i.e., “countergradient” production) at high latitudes. At the global scale, there were apparent unimodal relationships between community fish production measures and species richness; however, these patterns became linearized or non‐significant at the continental scale. Decreased interspecific competition at northern latitudes combined with genetic adaptations (e.g., countergradient growth) could explain a tendency for increased species production in northern populations, while total community production remains reduced. Latitude has contrasting effects on fish production at different spatial scales and levels of biological organization. Thus while freshwater fish communities are somewhat more productive and diverse at lower latitudes, species production in northern populations is often surprisingly high.

Species mixture effects on flammability across plant phylogeny: the importance of litter particle size and the special role for non-Pinus Pinaceae.

Fire affects and is affected by plants. Vegetation varies in flammability, that is, its general ability to burn, at different levels of ecological organization. To scale from individual plant traits to community flammability states, understanding trait effects on species flammability variation and their interaction is important. Plant traits are the cumulative result of evolution and they show, to differing extents, phylogenetic conservatism. We asked whether phylogenetic distance between species predicts species mixture effects on litterbed flammability. We conducted controlled laboratory burns for 34 phylogenetically wide‐ranging species and 34 random two‐species mixtures from them. Generally, phylogenetic distance did not predict species mixture effects on flammability. Across the plant phylogeny, most species were flammable except those in the non‐Pinus Pinaceae, which shed small needles producing dense, poorly ventilated litterbeds above the packing threshold and therefore nonflammable. Consistently, either positive or negative dominance effects on flammability of certain flammable or those non‐flammable species were found in mixtures involving the non‐Pinus Pinaceae. We demonstrate litter particle size is key to explaining species nonadditivity in fuelbed flammability. The potential of certain species to influence fire disproportionately to their abundance might increase the positive feedback effects of plant flammability on community flammability state if flammable species are favored by fire.

Adaptive foragers and community ecology: linking individuals to communities and ecosystems

Adaptive foragers and community ecology: linking individuals to communities and ecosystems

Different Effects of Species Diversity on Temporal Stability in Single‐Trophic and Multitrophic Communities

The question of how species diversity affects ecological stability has long interested ecologists and yet remains largely unresolved. Historically, attempts to answer this question have been hampered by the presence of multiple potentially confounding stability concepts, confusion over responses at different levels of ecological organization, discrepancy between theoretical predictions, and, particularly, the paucity of empirical studies. Here we used meta-analyses to synthesize results of empirical studies published primarily in the past 2 decades on the relationship between species diversity and temporal stability. We show that the overall effect of increasing diversity was positive for community-level temporal stability but neutral for population-level temporal stability. There were, however, striking differences in the diversity-stability relationship between single- and multitrophic systems, with diversity stabilizing both population and community dynamics in multitrophic but not single-trophic communities. These patterns were broadly equivalent across experimental and observational studies as well as across terrestrial and aquatic studies. We discuss possible mechanisms for population stability to increase with diversity in multitrophic systems and for diversity to influence community-level stability in general. Overall, our results indicate that diversity can affect temporal stability, but the effects may critically depend on trophic complexity.

Vertical gradients in leaf trait diversity in a New Zealand forest

Leaves come in a remarkable diversity of sizes and shapes. However, spatial patterns in leaf trait diversity are rarely investigated and poorly resolved. We used a hierarchical approach to evaluate vertical variability in leaf morphology (i.e., leaf trait diversity) in 16 common tree and shrub species inhabiting a New Zealand forest. Height-related heterogeneity in leaf area, specific leaf area, circularity and length to width ratio was analyzed at three scales: (1) among leaves within plants, (2) among plants within species and (3) among species within functional groups (i.e., trees vs. shrubs). Results were scale dependent. Among-leaf morphological diversity was unrelated to plant height. Among-individual morphological diversity increased with the average height of each species, indicating that taller plant species express a greater range of leaf traits than shorter species. Among-species morphological diversity was higher in shrubs than in trees. We hypothesize that scale-dependent patterns in leaf trait diversity result from scale-dependent adaptations to forest environmental conditions. As trees grow from the forest floor into the canopy, they are exposed to a range of environmental conditions, which may select for a range of leaf traits through ontogeny. Conversely, shrubs never reach the forest canopy and may instead be differentially adapted to suites of environmental conditions associated with different stages of forest recovery from tree-fall disturbances. Overall results indicate that vertical patterns in leaf trait diversity exist. However, their strength and directionality are strongly scale-dependent, suggesting that different processes govern leaf shape diversity at different levels of ecological organization.

Seasonal energetic constraints in Mediterranean benthic suspension feeders: effects at different levels of ecological organization

The aim of this work is to examine the role of food as a constraining factor at different levels of ecological organization in benthic littoral ecosystems. In the search for patterns in ecological systems, it has recently been documented that seasonality in the dynamics of benthic suspension feeders (BSF) in the Mediterranean Sea is characterized by summer dormancy. We review recent studies on seston availability in the water column and feeding and respiration by BSF in the Mediterranean. The objective is to assess whether a pattern across particular studies exists that could provide evidence of food as a constraining factor. A pattern emerges from these organism‐level studies, one which indicates the seasonal occurrence of an energy shortage in the taxa exhibiting summer dormancy. This energy shortage is closely related to low food availability and suggests that an energetic constraint underlie the summer dormancy phenomenon. The seasonal occurrence of summer energy shortage also appears to affect the dynamics of BSF at population and community level. In this sense, in late summer 1999, a mass mortality event of BSF affected several hundreds of kilometers in the Ligurian Sea (NW Mediterranean). The fact that the mass mortality event occurred in late summer and especially affected the taxa that exhibit energy shortage – such as anthozoans and sponges – suggests, that energetic constraints may contribute to the understanding of the mass mortality event. The energy shortage phenomenon may provide a mechanism to understand how the occurrence of anomalous climatic conditions may have induced the mass mortality of some BSF taxa. This review points out the existence of a common energy shortage phenomenon mainly related to low food availability as an important determinant of the dynamics of most BSF taxa at organism level in the Mediterranean. But this determinant also affects the dynamics of BSF at population and community level. Therefore, the extant data point up the crucial role of food as a constraining factor for benthic littoral ecosystems in oligotrophic areas like the Mediterranean, with important seasonal variations in seston abundance and composition.

Review and assessment of biotic variables and analytical methods used in estuarine inflow studies

Published and gray literature, and works in progress, were reviewed to identify biotic variables and analytical methods used in studying freshwater inflow needs of estuaries. Landings, CPUE, and other measures of single-species abundance are most often used, especially for shellfish and finfish. These efforts work best when biomass is used and lag times are allowed for recruitment, but neither method is always used, and most efforts have assumed that physical habitat availability is constant. Efforts employing habitat and community-level variables are used less often but more recent attempts are using dynamic as well as stationary definitions of habitat. Even stationary habitat methods have given less attention to tidal freshwater and brackish estuarine reaches, than to other reaches. Natural long-period climate cycles (El Nino Southern Oscillation; North Atlantic Multi-Decadal Oscillation) are not factored into most inflow studies. Three promising approaches are encouraged; a mixture of variables representing different levels of ecological organization should be used, the natural non-linear geometry of estuaries (especially tidal rivers) should be exploited to identify critical thresholds of inflow, and the validity of using instream flow methods to calculate estuarine requirements by proxy should be determined.

Boundaries and Corridors as a Continuum of Ecological Flow Control: Lessons from Rivers and Streams

Abstract: Landscape boundaries and corridors are areas of small spatial extent relative to their large effects on ecological flows. The trend in ecological literature is to treat corridors and boundaries as separate phenomena on the landscape. This approach, however, misses a fundamental aspect they have in common: their strong influence on ecological flows. Corridors and boundaries exist at opposite ends of a permeability gradient, differing in their effects on rates and direction of flow. The position of landscape structures along this permeability gradient depends on attributes of both the flow and of the structure itself. We discuss boundaries and corridors in terms of mover specificity, scale, and effects on different levels of ecological organization, using rivers and streams to illustrate our points. We predict which structures will act as boundaries or corridors and at what spatial and temporal scales they are likely to be relevant. Considering the function of landscape structures across the boundary‐corridor continuum will provide researchers and managers with a more complete, holistic viewpoint and will allow better strategies to attain conservation goals.

Dynamic structure of a food web model: comparison with a food chain model

In this paper the dynamic behaviour of a food web model with a high diversity in time scales and function is contrasted with the dynamic behaviour of a food chain model. The models describe the trophic dynamics in pelagic systems. Body weight is chosen as the central variable determining an organism's dynamic and ecological properties. In the web model consumers are further distinguished by the selectivity of their feeding behaviour. Because of its dynamic and flexible network, the web model buffers the effects of structural changes such as adding a top predator and changes in the environment such as altering nutrient input. This behaviour is in sharp contrast to the sensitivity of the chain model. The transfer of energy up the trophic gradient proves to be far more efficient in the web than in the chain model. This article provides an example of a systematic approach to investigating the influence of structural and dynamic complexity of ecological networks for ecosystem dynamics and function. Such approaches are essential for improving our understanding of ecosystem regulation and for bridging different levels of ecological organization.

Genetics of host-parasite interactions

The evolution of host susceptibility or resistance to parasites has important consequences for the evolution of parasite virulence, host sexual selection, population dynamics of both host and parasite populations, and programs of biological control. The general observation of a fraction of Individuals within a population that is not parasitized, and/or the variability in parasite intensity among hosts, may reflect several phenomena acting at different levels of ecological organization. Yet, host-parasite coevolution requires host susceptibility and parasite virulence to be genetically variable. In spite of evolutionary and epidemiological implications of genetic heterogeneities in host-parasite systems, evidence concerning natural populations is still scarce. Here, we wish to emphasize why we need a better knowledge of the genetics of host-parasite interaction in natural populations and to review the evidence concerning the heritability of host susceptibility or resistance to parasites in natural populations of animals.