scholarly journals A phenomenological spatial model for macro-ecological patterns in species-rich ecosystems

2016 ◽  
Author(s):  
Fabio Peruzzo ◽  
Sandro Azaele
Keyword(s):  
Spatial Scales ◽  
Pair Correlation ◽  
Initial Increase ◽  
Ecological Communities ◽  
Lowland Tropical Forest ◽  
Forest Inventories ◽  
Spatial Turnover ◽  
Ecological Patterns ◽  
Analytical Formulae ◽  
Commonness And Rarity

Over the last few decades, ecologists have come to appreciate that key ecological patterns, which describe ecological communities at relatively large spatial scales, are not only scale dependent, but also intimately intertwined. The relative abundance of species – which informs us about the commonness and rarity of species – changes its shape from small to large spatial scales. The average number of species as a function of area has a steep initial increase, followed by decreasing slopes at large scales. Finally, if we find a species in a given location, it is more likely we find an individual of the same species close-by, rather than farther apart. Such spatial turnover depends on the geographical distribution of species, which often are spatially aggregated. This reverberates on the abundances as well as the richness of species within a region, but so far it has been difficult to quantify such relationships.Within a neutral framework – which considers all individuals competitively equivalent – we introduce a spatial stochastic model, which phenomenologically accounts for birth, death, immigration and local dispersal of individuals. We calculate the pair correlation function – which encapsulates spatial turnover – and the conditional probability to find a species with a certain population within a given circular area. Also, we calculate the macro-ecological patterns, which we have referred to above, and compare the analytical formulæ with the numerical integration of the model. Finally, we contrast the model predictions with the empirical data for two lowland tropical forest inventories, showing always a good agreement.

scholarly journals The prevalence and impact of transient species in ecological communities

2017 ◽  
Author(s):  
Sara Snell ◽  
Brian S. Evans ◽  
Ethan P. White ◽  
Allen H. Hurlbert
Keyword(s):  
Spatial Scales ◽  
Species Abundance ◽  
Careful Consideration ◽  
Ecological Communities ◽  
Transient Species ◽  
Ecological Patterns ◽  
Species Abundance Distributions ◽  
Species Area ◽  
Using Data ◽  
Taxonomic Groups

AbstractTransient species occur infrequently in a community over time and do not maintain viable local populations. Because transient species interact differently than non-transients with their biotic and abiotic environment, it is important to characterize the prevalence of these species and how they impact our understanding of ecological systems. We quantified the prevalence and impact of transient species in communities using data on over 17,000 community time series spanning an array of ecosystems, taxonomic groups, and spatial scales. We found that transient species are a general feature of communities regardless of taxa or ecosystem. The proportion of these species decreases with spatial scale leading to a need to control for scale in comparative work. Removing transient species from analyses influences the form of a suite of commonly studied ecological patterns including species-abundance distributions, species-energy relationships, species-area relationships, and temporal turnover. Careful consideration should be given to whether transient species are included in analyses depending on the theoretical and practical relevance of these species for the question being studied.

scholarly journals Deriving Tree Size Distributions of Tropical Forests from Lidar

2021 ◽  
Vol 13 (1) ◽  
pp. 131
Author(s):  
Franziska Taubert ◽  
Rico Fischer ◽  
Nikolai Knapp ◽  
Andreas Huth
Keyword(s):  
Size Distribution ◽  
Spatial Scales ◽  
Basal Area ◽  
Tree Height ◽  
Tree Size ◽  
Diameter Distribution ◽  
Forest Inventories ◽  
Allometric Relations ◽  
Lidar Measurements ◽  
Derived Data

Remote sensing is an important tool to monitor forests to rapidly detect changes due to global change and other threats. Here, we present a novel methodology to infer the tree size distribution from light detection and ranging (lidar) measurements. Our approach is based on a theoretical leaf–tree matrix derived from allometric relations of trees. Using the leaf–tree matrix, we compute the tree size distribution that fit to the observed leaf area density profile via lidar. To validate our approach, we analyzed the stem diameter distribution of a tropical forest in Panama and compared lidar-derived data with data from forest inventories at different spatial scales (0.04 ha to 50 ha). Our estimates had a high accuracy at scales above 1 ha (1 ha: root mean square error (RMSE) 67.6 trees ha−1/normalized RMSE 18.8%/R² 0.76; 50 ha: 22.8 trees ha−1/6.2%/0.89). Estimates for smaller scales (1-ha to 0.04-ha) were reliably for forests with low height, dense canopy or low tree height heterogeneity. Estimates for the basal area were accurate at the 1-ha scale (RMSE 4.7 tree ha−1, bias 0.8 m² ha−1) but less accurate at smaller scales. Our methodology, further tested at additional sites, provides a useful approach to determine the tree size distribution of forests by integrating information on tree allometries.

scholarly journals Evolutionary origins for ecological patterns in space

2020 ◽  
Vol 117 (30) ◽  
pp. 17482-17490 ◽  
Author(s):  
Mark C. Urban ◽  
Sharon Y. Strauss ◽  
Fanie Pelletier ◽  
Eric P. Palkovacs ◽  
Mathew A. Leibold ◽  
...  
Keyword(s):  
Local Adaptation ◽  
Environmental Gradients ◽  
Spatial Scales ◽  
Keystone Species ◽  
Future Research ◽  
Evolutionary Divergence ◽  
Patch Selection ◽  
Fully Integrated ◽  
Evolutionary Origins ◽  
Ecological Patterns

Historically, many biologists assumed that evolution and ecology acted independently because evolution occurred over distances too great to influence most ecological patterns. Today, evidence indicates that evolution can operate over a range of spatial scales, including fine spatial scales. Thus, evolutionary divergence across space might frequently interact with the mechanisms that also determine spatial ecological patterns. Here, we synthesize insights from 500 eco-evolutionary studies and develop a predictive framework that seeks to understand whether and when evolution amplifies, dampens, or creates ecological patterns. We demonstrate that local adaptation can alter everything from spatial variation in population abundances to ecosystem properties. We uncover 14 mechanisms that can mediate the outcome of evolution on spatial ecological patterns. Sometimes, evolution amplifies environmental variation, especially when selection enhances resource uptake or patch selection. The local evolution of foundation or keystone species can create ecological patterns where none existed originally. However, most often, we find that evolution dampens existing environmental gradients, because local adaptation evens out fitness across environments and thus counteracts the variation in associated ecological patterns. Consequently, evolution generally smooths out the underlying heterogeneity in nature, making the world appear less ragged than it would be in the absence of evolution. We end by highlighting the future research needed to inform a fully integrated and predictive biology that accounts for eco-evolutionary interactions in both space and time.

scholarly journals Long-term data reveal unimodal responses of ground beetle abundance to precipitation and land use but no changes in taxonomic and functional diversity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Petr Zajicek ◽  
Ellen A. R. Welti ◽  
Nathan J. Baker ◽  
Kathrin Januschke ◽  
Oliver Brauner ◽  
...  
Keyword(s):  
Land Use ◽  
Functional Diversity ◽  
Spatial Scales ◽  
Ground Beetle ◽  
Temporal Trends ◽  
Ground Beetles ◽  
Community Change ◽  
Ecological Communities ◽  
Activity Density

AbstractWhile much of global biodiversity is undoubtedly under threat, the responses of ecological communities to changing climate, land use intensification, and long-term changes in both taxonomic and functional diversity over time, has still not been fully explored for many taxonomic groups, especially invertebrates. We compiled time series of ground beetles covering the past two decades from 40 sites located in five regions across Germany. We calculated site-based trends for 21 community metrics representing taxonomic and functional diversity of ground beetles, activity density (a proxy for abundance), and activity densities of functional groups. We assessed both overall and regional temporal trends and the influence of the global change drivers of temperature, precipitation, and land use on ground beetle communities. While we did not detect overall temporal changes in ground beetle taxonomic and functional diversity, taxonomic turnover changed within two regions, illustrating that community change at the local scale does not always correspond to patterns at broader spatial scales. Additionally, ground beetle activity density had a unimodal response to both annual precipitation and land use. Limited temporal change in ground beetle communities may indicate a shifting baseline, where community degradation was reached prior to the start of our observation in 1999. In addition, nonlinear responses of animal communities to environmental change present a challenge when quantifying temporal trends.

scholarly journals Ecotones: Marginal or central areas of transition?

2006 ◽  
Vol 52 (1) ◽  
pp. 29-53 ◽  
Author(s):  
Salit Kark ◽  
Berndt J. van Rensburg
Keyword(s):  
Environmental Gradients ◽  
Spatial Scales ◽  
Small Scale ◽  
Biodiversity Hotspots ◽  
Ecological Communities ◽  
Marginal Populations ◽  
Multiple Spatial Scales ◽  
Scientific Attention

Areas of environmental transition, where ecological communities coincide, are sometimes termed ecotones. These regions often correspond with sharp environmental gradients. Ecotones occur at multiple spatial scales, ranging from transitions between biomes to local small-scale transitions. In recent years ecotones have received increasing scientific attention after being neglected for years, as studies historically often focused on distinct communities. However, it is still debatable whether these transitional regions are speciation and biodiversity hotspots that deserve special conservation interest or are actually areas that hold marginal populations that depend on other parts of the range for the maintenance of their biodiversity and therefore should not deserve primary investment. This paper discusses some of the recent advancements in our understanding of the role of ecotones in ecology, evolution, and conservation.

scholarly journals The macroecology of rapid evolutionary radiation

2011 ◽  
Vol 278 (1717) ◽  
pp. 2486-2494 ◽  
Author(s):  
Nicholas F. Parnell ◽  
J. Todd Streelman
Keyword(s):  
Adaptive Radiation ◽  
Species Interactions ◽  
Spatial Scales ◽  
Ecological Communities ◽  
Core Set ◽  
Evolutionary Radiation ◽  
Local Species ◽  
Entire Lake ◽  
Insight Into ◽  
Occurrence Of Species

A long-standing debate in ecology addresses whether community composition is the result of stochastic factors or assembly rules. Non-random, over-dispersed patterns of species co-occurrence have commonly been attributed to competition—a particularly important force in adaptive radiation. We thus examined the macroecology of the recently radiated cichlid rock-fish assemblage in Lake Malawi, Africa at a spectrum of increasingly fine spatial scales (entire lake to depth within rock-reef sites). Along this range of spatial scales, we observed a signal of community structure (decreased co-occurrence of species) at the largest and smallest scales, but not in between. Evidence suggests that the lakewide signature of structure is driven by extreme endemism and micro-allopatric speciation, while patterns of reduced co-occurrence with depth are indicative of species interactions. We identified a ‘core’ set of rock-reef species, found in combination throughout the lake, whose depth profiles exhibited replicated positive and negative correlation. Our results provide insight into how ecological communities may be structured differently at distinct spatial scales, re-emphasize the importance of local species interactions in community assembly, and further elucidate the processes shaping speciation in this model adaptive radiation.

scholarly journals Evidence for large-scale effects of competition: niche displacement in Canada lynx and bobcat

2013 ◽  
Vol 280 (1773) ◽  
pp. 20132495 ◽  
Author(s):  
Michael J. L. Peers ◽  
Daniel H. Thornton ◽  
Dennis L. Murray
Keyword(s):  
Large Scale ◽  
Scale Effects ◽  
Spatial Scales ◽  
Biotic Interactions ◽  
Character Displacement ◽  
Lynx Rufus ◽  
Ecological Communities ◽  
Lynx Canadensis ◽  
Distribution Models ◽  
Canada Lynx

Determining the patterns, causes and consequences of character displacement is central to our understanding of competition in ecological communities. However, the majority of competition research has occurred over small spatial extents or focused on fine-scale differences in morphology or behaviour. The effects of competition on broad-scale distribution and niche characteristics of species remain poorly understood but critically important. Using range-wide species distribution models, we evaluated whether Canada lynx ( Lynx canadensis ) or bobcat ( Lynx rufus ) were displaced in regions of sympatry. Consistent with our prediction, we found that lynx niches were less similar to those of bobcat in areas of sympatry versus allopatry, with a stronger reliance on snow cover driving lynx niche divergence in the sympatric zone. By contrast, bobcat increased niche breadth in zones of sympatry, and bobcat niches were equally similar to those of lynx in zones of sympatry and allopatry. These findings suggest that competitively disadvantaged species avoid competition at large scales by restricting their niche to highly suitable conditions, while superior competitors expand the diversity of environments used. Our results indicate that competition can manifest within climatic niche space across species’ ranges, highlighting the importance of biotic interactions occurring at large spatial scales on niche dynamics.

scholarly journals The phylogeny of Critical Zone Observatories, or how to better structure existing observation networks to match the whole system approach

2021 ◽  
Author(s):  
Isabelle Braud ◽  
Jérôme Gaillardet ◽  
François Mercier ◽  
Sylvie Galle ◽  
Virginie Entringer
Keyword(s):  
System Approach ◽  
Spatial Scales ◽  
National Level ◽  
Monitoring Network ◽  
Critical Zone ◽  
Visualization Tool ◽  
Ecological Communities ◽  
Continental Scale ◽  
Observation Networks

<p>Implementing the Whole System Approach for long-term ecosystem, critical zone and socio-ecological system research requires going beyond existing structuration of scientific communities and observation networks. Indeed, existing observation networks were often built independently from each other, on a very disciplinary basis, with their own scientific objectives, funding mechanisms and institutional constraints. To tackle the observation challenges of the “new climatic regime” in the Anthropocene, a new type of observational platforms, more compatible with a scientific systemic approach needs to be built taking into account the history and institutional contexts of long-term observatories.</p><p><br>We have attempted to represent the diversity of critical zone observatories, sites and network of observatories that exist and that have been founded by different research institutions in France over the last 40 years and that are now gathered in the OZCAR Critical Zone network. Our representation encapsulates three main characteristics: the spatial scales of investigation (from the plot scale to the continental-scale watershed), the diversity of monitored compartments (catchments, glaciers, peatlands, aquifers…), and the institutional dimension (labeling and founding at the national level).  We found that a representation in the form of a tree, mimicking the phylogenetic tree of life, named the OZCAR-tree, was offering a visualization tool able to capture the philosophy and rationale of the network and was useful to improve the communication with the neighboring infrastructures, users and stakeholders. The branches of the tree represent the nested monitored scales, with the small branches of the tree representing monitored parcels or small catchments. The trunks represent networks of sites investigating the same compartment. For monitored catchments, the representation directly shows the various sampled scales and their nested organization from upstream to downstream. At each site, colored pie charts allow us to visualize rapidly the types of data that are collected, each part of the pie being a component of the critical zone (atmosphere, soil water, aquifers, vegetation, snow, ice…). This visualization directly shows the focus of the various sites, the completeness of measurements conducted by the different scientists, but also the missing compartments. It also shows that, if the network, as a whole is able to sample the various compartments and variables required for implementing the whole system approach, it is rarely the case when considering individual sites.</p><p>Beyond being a visualization tool, the OZCAR-tree helps representing the requirements of a “whole critical zone approach”. Because all compartments of the critical zone are connected vertically and horizontally by processes and fluxes of energy and matter, the tree is meant to represent all the components to be monitored and what should be the spatial architecture of a monitoring network fulfilling the disciplinary questions and approaches. The tree is therefore an illustration of a conceptual and idealized network (devoid of cost issues) of terrestrial surfaces monitoring infrastructure respectful of disciplinary approaches.</p><p>Finally, this representation is open to ecological and socio-ecological communities and may serve as a template for fostering collaboration with ecological and socio-ecological communities and networks and implementing observation platforms at the scale of changing territories.</p>

scholarly journals A unified model of species abundance, genetic diversity, and functional diversity reveals the mechanisms structuring ecological communities

2020 ◽  
Author(s):  
Isaac Overcast ◽  
Megan Ruffley ◽  
James Rosindell ◽  
Luke Harmon ◽  
Paulo A. V. Borges ◽  
...  
Keyword(s):  
Community Assembly ◽  
Island Biogeography ◽  
Spatial Scales ◽  
Mechanistic Model ◽  
Species Abundance ◽  
Real Data ◽  
Current Theory ◽  
Supervised Machine Learning ◽  
Ecological Communities ◽  
Trait Variation

AbstractBiodiversity accumulates hierarchically by means of ecological and evolutionary processes and feedbacks. Reconciling the relative importance of these processes is hindered by current theory, which tends to focus on a single spatial, temporal or taxonomic scale. We introduce a mechanistic model of community assembly, rooted in classic island biogeography theory, which makes temporally explicit joint predictions across three biodiversity data axes: i) species richness and abundances; ii) population genetic diversities; and iii) trait variation in a phylogenetic context. We demonstrate that each data axis captures information at different timescales, and that integrating these axes enables discriminating among previously unidentifiable community assembly models. We combine our massive eco-evolutionary synthesis simulations (MESS) with supervised machine learning to fit the parameters of the model to real data and infer processes underlying how biodiversity accumulates, using communities of tropical trees, arthropods, and gastropods as case studies that span a range of spatial scales.

scholarly journals Previous oil exposure alters oil avoidance behavior in a common marsh fish, the Gulf Killifish Fundulus grandis

2020 ◽  
Author(s):  
Charles W. Martin ◽  
Ashley M. McDonald ◽  
Guillaume Rieucau ◽  
Brian J. Roberts
Keyword(s):  
Oil Spills ◽  
Spatial Scales ◽  
Chemical Constituents ◽  
Field Studies ◽  
Future Research ◽  
Ecological Communities ◽  
Fundulus Grandis ◽  
Individual Level ◽  
Marine Disasters ◽  
Oil Exposure

AbstractOil spills threaten the structure and function of ecological communities. In the northern Gulf of Mexico, the 2010 Deepwater Horizon spill was among the largest marine disasters in history. While many predicted catastrophic consequences for nearshore fishes, field studies indicate surprising resilience in populations and communities. One potential mechanism for this resilience is the recognition and behavioral avoidance at small spatial scales of the toxic chemical constituents found in oil. Previous research indicates many marsh fishes have the capacity to avoid oil contaminated areas. Here, we test whether prior oil exposure of a common marsh fish, the Gulf killifish Fundulus grandis, alters this avoidance response. Using choice tests between unoiled and a range of oiled sediments, we found that, even at low levels of previous exposure, killifish lose recognition of oiled sediments. Preference for unoiled sediments was lost across the entire range of oil concentrations tested here after oil exposure, and some evidence for preference of oiled sediments was even demonstrated. These results provide evidence for lack of response to toxic environments in exposed individuals, suggesting sublethal impairment of sensory mechanisms on an individual level despite organism survival. Future research should highlight additional sublethal consequences that affect ecosystem and food web functioning.

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