scholarly journals The emergent interactions that govern biodiversity change

2020 ◽  
Vol 117 (29) ◽  
pp. 17074-17083 ◽  
Author(s):  
James S. Clark ◽  
C. Lane Scher ◽  
Margaret Swift
Keyword(s):  
Species Interactions ◽  
Environmental Gradients ◽  
Local Population ◽  
Species Abundance ◽  
Community Change ◽  
Model Specification ◽  
Data Simulation ◽  
Breeding Bird ◽  
Probabilistic Uncertainty ◽  
Nonlinear Responses

Observational studies have not yet shown that environmental variables can explain pervasive nonlinear patterns of species abundance, because those patterns could result from (indirect) interactions with other species (e.g., competition), and models only estimate direct responses. The experiments that could extract these indirect effects at regional to continental scales are not feasible. Here, a biophysical approach quantifies environment– species interactions (ESI) that govern community change from field data. Just as species interactions depend on population abundances, so too do the effects of environment, as when drought is amplified by competition. By embedding dynamic ESI within framework that admits data gathered on different scales, we quantify responses that are induced indirectly through other species, including probabilistic uncertainty in parameters, model specification, and data. Simulation demonstrates that ESI are needed for accurate interpretation. Analysis demonstrates how nonlinear responses arise even when their direct responses to environment are linear. Applications to experimental lakes and the Breeding Bird Survey (BBS) yield contrasting estimates of ESI. In closed lakes, interactions involving phytoplankton and their zooplankton grazers play a large role. By contrast, ESI are weak in BBS, as expected where year-to-year movement degrades the link between local population growth and species interactions. In both cases, nonlinear responses to environmental gradients are induced by interactions between species. Stability analysis indicates stability in the closed-system lakes and instability in BBS. The probabilistic framework has direct application to conservation planning that must weigh risk assessments for entire habitats and communities against competing interests.

scholarly journals Evolutionary Responses to Conditionality in Species Interactions across Environmental Gradients

2018 ◽  
Vol 192 (6) ◽  
pp. 715-730 ◽  
Author(s):  
Anna M. O’Brien ◽  
Ruairidh J. H. Sawers ◽  
Jeffrey Ross-Ibarra ◽  
Sharon Y. Strauss
Keyword(s):  
Species Interactions ◽  
Environmental Gradients

Benthic species as mud patrol - modelled effects of bioturbators and biofilms on large-scale estuarine mud and morphology

2021 ◽  
Author(s):  
Muriel Brückner ◽  
Christian Schwarz ◽  
Giovanni Coco ◽  
Anne Baar ◽  
Márcio Boechat Albernaz ◽  
...  
Keyword(s):  
Morphological Change ◽  
Species Interactions ◽  
Large Scale ◽  
Habitat Degradation ◽  
Species Abundance ◽  
Estuarine Sediments ◽  
Morphological Development ◽  
Benthic Species ◽  
Species Dominance ◽  
Species Specific

<p>Benthic species that live within estuarine sediments stabilize or destabilize local mud deposits through their eco-engineering activities, affecting the erosion of intertidal sediments. Possibly, the altered magnitudes in eroded sediment affect the large-scale redistribution of fines and hence morphological change. To quantify this biological control on the morphological development of estuaries, we numerically model i) biofilms, ii) two contrasting bioturbating species present in NW-Europe, and iii) their combinations by means of our novel eco-morphodynamic model. The model predicts local mud erodibility based on species pattern, which dynamically evolves from the hydrodynamics, soil mud content, competition and grazing, and is fed back into the hydromorphodynamic computations.</p><p>We find that biofilms reduce mud erosion on intertidal floodplains and stabilize estuarine morphology, whereas the two bioturbators significantly enhance inter- and supratidal mud erosion and bed elevation change, leading to a large-scale reduction in deposited mud and a widening of the estuary. In turn, the species-dependent changes in mud content redefines their habitat and leads to a redistribution of species abundances. Here, the eco-engineering affects habitat conditions and species abundance while species interactions determine species dominance. Our results show that species-specific biostabilization and bioturbation determine large-scale morphological change through mud redistribution, and at the same time affect species distribution. This suggests that benthic species have subtly changed estuarine morphology through space and time and that aggravating habitat degradation might lead to large effects on the morphology of future estuaries.</p>

Community Ecology

Ecology ◽  
2012 ◽  
Author(s):  
Herman A. Verhoef
Keyword(s):  
Community Ecology ◽  
Evolutionary Biology ◽  
Environmental Gradients ◽  
Functional Integration ◽  
Species Abundance ◽  
Functional Trait ◽  
Individual Species ◽  
Global Changes ◽  
Ecological Communities ◽  
Early 21St Century

At the beginning of the 20th century there was much debate about the “nature” of communities. The driving question was whether the community was a self-organized system of co-occurring species or simply a haphazard collection of populations with minimal functional integration. At that time, two extreme views dominated the discussion: one view considered a community as a superorganism, the member species of which were tightly bound together by interactions that contributed to repeatable patterns of species abundance in space and time. This concept led to the assumption that communities are fundamental entities, to be classified as the Linnaean taxonomy of species. Frederick E. Clements was one of the leading proponents of this approach, and his view became known as the organismic concept of communities. This assumes a common evolutionary history for the integrated species. The opposite view was the individualistic continuum concept, advocated by H. A. Gleason. His focus was on the traits of individual species that allow each to live within specific habitats or geographical ranges. In this view a community is an assemblage of populations of different species whose traits allow persisting in a prescribed area. The spatial boundaries are not sharp, and the species composition can change considerably. Consequently, it was discussed whether ecological communities were sufficiently coherent entities to be considered appropriate study objects. Later, consensus was reached: that properties of communities are of central interest in ecology, regardless of their integrity and coherence. From the 1950s and 1960s onward, the discussion was dominated by the deterministic outcome of local interactions between species and their environments and the building of this into models of communities. This approach, indicated as “traditional community ecology,” led to a morass of theoretical models, without being able to provide general principles about many-species communities. Early-21st-century approaches to bringing general patterns into community ecology concern (1) the metacommunity approach, (2) the functional trait approach, (3) evolutionary community ecology, and (4) the four fundamental processes. The metacommunity approach implicitly recognizes and studies the important role of spatiotemporal dynamics. In the functional trait approach, four themes are focused upon: traits, environmental gradients, the interaction milieu, and performance currencies. This functional, trait-focused approach should have a better prospect of understanding the effects of global changes. Evolutionary community ecology is an approach in which the combination of community ecology and evolutionary biology will lead to a better understanding of the complexity of communities and populations. The four fundamental processes are selection, drift, speciation, and dispersal. This approach concerns an organizational scheme for community ecology, based on these four processes to describe all existing specific models and frameworks, in order to make general statements about process–pattern connections.

scholarly journals Evolutionary responses to conditionality in species interactions across environmental gradients

2015 ◽  
Author(s):  
Anna M. O’Brien ◽  
Ruairidh J.H. Sawers ◽  
Jeffrey Ross-Ibarra ◽  
Sharon Y. Strauss
Keyword(s):  
Statistical Models ◽  
Species Interactions ◽  
Environmental Gradients ◽  
Niche Partitioning ◽  
Character Displacement ◽  
Arms Race ◽  
Positive Interactions ◽  
Common Pattern ◽  
Interacting Species ◽  
Stressful Environments

AbstractThe outcomes of many species interactions are conditional on the environments in which they occur. A common pattern is that outcomes grade from being more positive under stressful conditions to more antagonistic or neutral under benign conditions. The evolutionary implications of conditionality in interactions have received much less attention than the documentation of conditionality itself, with a few notable exceptions. Here, we predict patterns of adaptation and co-adaptation between partners along abiotic gradients, positing that when interactions become more positive in stressful environments, fitness outcomes for mutations affecting interactions align across partners and selection should favor greater mutualistic adap-tation and co-adaptation between interacting species. As a corollary, in benign environments, if interactions are strongly antagonistic, we predict antagonistic co-adaptation resulting in Red Queen or arms-race dynamics, or reduction of antagonism through character displacement and niche partitioning. We predict no adaptation if interactions are more neutral. We call this the CoCoA hypothesis: (Co)-adaptation and Conditionality across Abiotic gradients. We describe experimental designs and statistical models that allow testing predictions of CoCoA, with a focus on positive interactions. While only one study has included all the elements to test CoCoA, we briefly review the literature and summarize study findings relevant to CoCoA and highlight opportunities to test CoCoA further.

scholarly journals Describing macroecological patterns in microbes: Approaches for comparative analyses of operational taxonomic unit read number distribution with a case study of global oceanic bacteria

2019 ◽  
Author(s):  
Ryosuke Nakadai ◽  
Yusuke Okazaki ◽  
Shunsuke Matsuoka
Keyword(s):  
Bacterial Communities ◽  
High Throughput Sequencing ◽  
Environmental Gradients ◽  
Species Abundance ◽  
Operational Taxonomic Unit ◽  
Tree Communities ◽  
Species Abundance Distributions ◽  
Similarities And Differences ◽  
Read Number ◽  
Commonness And Rarity

AbstractDescribing the variation in commonness and rarity in a community is a fundamental method of evaluating biodiversity. Such patterns have been studied in the context of species abundance distributions (SADs) among macroscopic organisms in numerous communities. Recently, models for analyzing variation in local SAD shapes along environmental gradients have been constructed. The recent development of high-throughput sequencing enables evaluation of commonness and rarity in local communities of microbes using operational taxonomic unit (OTU) read number distributions (ORDs), which are conceptually similar to SADs. However, few studies have explored the variation in local microbial ORD shapes along environmental gradients. Therefore, the similarities and differences between SADs and ORDs are unclear, clouding any universal rules of global biodiversity patterns. We investigated the similarities and differences in ORD shapes vs. SADs, and how well environmental variables explain the variation in ORDs along latitudinal and depth gradients. Herein, we integrate ORDS into recent comparative analysis methods for SAD shape using datasets generated on the Tara Oceans expedition. About 56% of the variance in skewness of ORDs among global oceanic bacterial communities was explained with this method. Moreover, we confirmed that the parameter combination constraints of Weibull distributions were shared by ORDs of bacterial communities and SADs of tree communities, suggesting common long-term limitation processes such as adaptation and community persistence acting on current abundance variation. On the other hand, skewness was significantly greater for bacterial communities than tree communities, and many ecological predictions did not apply to bacterial communities, suggesting differences in the community assembly rules for microbes and macroscopic organisms. Approaches based on ORDs provide opportunities to quantify macroecological patterns of microbes under the same framework as macroscopic organisms.

scholarly journals Increasing temporal variance leads to stable species range limits

2021 ◽  
Author(s):  
John W Benning ◽  
Ruth A Hufbauer ◽  
Christopher Weiss-Lehman
Keyword(s):  
Environmental Gradient ◽  
Environmental Gradients ◽  
Local Population ◽  
Evolutionary Model ◽  
Environmental Variation ◽  
Species Range ◽  
Range Limits ◽  
Stable Range ◽  
Species Expansion ◽  
Temporal Variance

What prevents populations of a species from adapting to the novel environments outside the species' geographic distribution? Previous models highlighted how gene flow across spatial environmental gradients determines species expansion vs. extinction and the location of species range limits. However, space is only one of two axes of environmental variation — environments also vary in time, and we know temporal environmental variation has important consequences for population demography and evolution. We used an individual based evolutionary model to explore how temporal stochasticity in environmental conditions influences the spread of populations across a spatial environmental gradient. We find that temporal stochasticity greatly alters our predictions for range dynamics compared to temporally static environments. When temporal variance is equal across the landscape, the fate of species (expansion vs. extinction) is determined by the interaction between the degree of temporal autocorrelation in environmental fluctuations and the steepness of the spatial environmental gradient. When the magnitude of temporal variance changes across the landscape, stable range limits form where this variance becomes large enough to prevent local population adaptation and persistence. These results illustrate the pivotal influence of temporal stochasticity on the likelihood of populations colonizing novel habitats and the location of species range limits.

Facilitation and the Organization of Communities

Ecology ◽  
2012 ◽  
Author(s):  
Christopher J. Lortie
Keyword(s):  
Species Interactions ◽  
Environmental Gradients ◽  
Plant Competition ◽  
Historical Background ◽  
Positive Interactions ◽  
Plant Interactions ◽  
Reciprocal Effect ◽  
Early 21St Century ◽  
Analytical Approaches ◽  
Plant Plant

Species interactions are a cornerstone of ecological research wherein the effects of an individual of one species on another individual, frequently a different species, are studied. Within versus between species interactions are also commonly contrasted as a means to infer relative importance, but the majority of theory advances, at least at the community level, are associated with interactions between individuals of different species. Interactions can range from positive to negative, and effects are measured at all levels of development, or life history stages, of an organism. Positive interactions have been extensively studied in both population and community ecology. Facilitation, however, is a relatively specific term that has evolved primarily to describe positive plant–plant interactions (see Defining Facilitation). Facilitation, or positive interactions, is a relatively recent subset of these species interactions in general, including related processes, such as competition, mutualism, and parasitism. Facilitation is best viewed as the antithesis of the plant competition literature, as it shares many of the main attributes, both in terms of scope and approach, and arose as a comparator to this research. Facilitation studies mainly refer to positive plant–plant interactions, as the term was proposed in the plant literature and extensively used to describe interactions that include a positive effect of one species on another. Mutualism and parasitism research is often plant–insect based and formally identifies the reciprocal effect in the interaction, that is, (+, +) in mutualism and (+,−) in parasitism, whereas facilitation studies are generally (+,0) or (+,?), with the second effect often unreported. Interactions that include at least one negative interaction are usually described as competition in the plant literature and do not apply the term facilitation (although the frequency of both being discussed concomitantly is increasing). Hence, the term facilitation, owing to historical use, describes the subset of interactions that are (+,0) and is mostly specific to within plants, although its usage is expanding. The research on facilitation has most likely peaked, similar to plant competition studies, in that facilitation has been clearly established as an important process in the formation of plant communities. Additional studies simply demonstrating facilitation are increasing unlikely to be present in the literature. That said, the implications to theory and other, more nuanced aspects of interaction, such as context dependence, shifting balances, and importance of the environment, as they relate to facilitation, are still largely unexplored. In the early 21st century the most contentious debates, with respect to facilitation, center on either disagreement concerning what a community is and whether research should be conducted at this scale or on how to use environmental gradients (i.e., stress) most effectively. Both of these topics are described herein, with readings also included on Historical Background, Experimental and Analytical Approaches, Evolution, other taxa, and Applications.

Density Trends and Range Boundary Constraints of Forest Birds Along a Latitudinal Gradient

The Auk ◽  
1986 ◽  
Vol 103 (4) ◽  
pp. 791-803 ◽  
Author(s):  
John T. Emlen ◽  
Michael J. DeJong ◽  
Michael John Jaeger ◽  
Timothy C. Moermond ◽  
Kurt A. Rusterholz ◽  
...  
Keyword(s):  
Habitat Structure ◽  
Deciduous Forest ◽  
Climatic Factors ◽  
Environmental Gradients ◽  
Species Abundance ◽  
Bird Species ◽  
Population Data ◽  
Day Length ◽  
Latitudinal Gradients ◽  
Habitat Factors

Abstract We plotted the density distributions of 41 land-bird species along a 1,200-km transect spanning 7°28′ (865 km) of latitude through relatively uniform bottomland deciduous forest in middle North America. Standardized counts and observations at 12 survey stations, closely matched in habitat structure and widely distributed along the route, provided population data for all species and indices of total avian foraging pressure (consuming biomass) on each of six major foraging substrates. Density curves for species fluctuated considerably from station to station but tended to be level across range centers and slope peripherally to north and south boundaries at rates of 3-30% per degree of latitude. Substrate foraging pressures declined northward on the aerial and midfoliage substrates and southward on the low-foliage substrate. Summed community densities showed no significant latitudinal trends. We used the distinctive distribution patterns of climate (smooth latitudinal gradients), habitat structure (irregular mosaics of vegetation patches), and competition (reciprocally sloping density gradients) to identify and evaluate the role of these three constraints along the transect. Progressive latitudinal trends in species abundance thus were attributed to climatic factors, irregular station-to-station fluctuations to habitat factors, and inversely sloping density trends in paired profiles to competition. On this basis all species apparently responded to both climatic and habitat factors, and about half of the species showed suggestions of competition. In a correlation analysis across the 12 stations, latitude per se most closely matched density distribution in 12 species, one or another of the habitat parameters in 25 species. We proposed that season length (days available for breeding activity) was the principal constraining attribute of latitude at northern range boundaries, day length (hours available for feeding and provisioning young) at southern boundaries. Boundaries have been essentially stable during the past 50-100 yr in most species, but the northern boundary expanded northward in one species following human-induced habitat enhancement, and temporarily receded southward in another following a winter of severe stress. We attribute this general stability of range boundaries over time to within-population gene flow and the associated peripherally declining mean fitness of phenotypes adapted to central range conditions along radially diverging environmental gradients. We suggest that two boundary lines should be recognized for each species, an inner functional boundary at the line where birth rates drop below death rates, and an outer empirical boundary at the limit of recorded occurrences.

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