The spatial configuration of biotic interactions shapes coexistence-area relationships in an annual plant community

AbstractThe increase of species richness with area is a universal phenomenon on Earth. However, this observation contrasts with our poor understanding of how these species-area relationships (SARs) emerge from the collective effects of area, spatial heterogeneity, and local interactions. By combining a structuralist approach with five years of empirical observations in a highly-diverse Mediterranean grassland, we show that spatial heterogeneity plays a little role in the accumulation of species richness with area in our system. Instead, as we increase the sampled area more species combinations are realized, and they coexist mainly due to direct pairwise interactions rather than by changes in single-species dominance or by indirect interactions. We also identify a small set of transient species with small population sizes that are consistently found across spatial scales. These findings empirically support the importance of the architecture of species interactions together with stochastic events for driving coexistence- and species-area relationships.

Download Full-text

Species-area relationships emerge from multiple coexistence mechanisms

10.1101/2021.04.02.438211 ◽

2021 ◽

Author(s):

David Garcia-Callejas ◽

Ignasi Bartomeus ◽

Oscar Godoy

Keyword(s):

Species Richness ◽

Spatial Heterogeneity ◽

Species Interactions ◽

Spatial Scales ◽

Single Species ◽

Small Population ◽

Collective Effects ◽

Demographic Stochasticity ◽

Species Dominance ◽

Species Area

The increase of species richness with area is a universal phenomenon on Earth. However, this observation contrasts with our poor understanding of how these species-area relationships (SARs) emerge from the collective effects of area, spatial heterogeneity, and local interactions. By combining a structuralist approach with five years of empirical observations in a highly-diverse grassland, we show that,contrary to expectations, spatial heterogeneity plays a little role in the accumulation of species richness with area in our system. Instead, as we increase the sampled area more species combinations are realized, and they coexist mainly due to direct pairwise interactions rather than by changes in single-species dominance or by indirect interactions. We also identify a small set of transient species with small population sizes that are consistently found across spatial scales. These findings empirically support the importance of the architecture of species interactions together with demographic stochasticity for driving SARs.

Download Full-text

Patterns of biological diversity

Community Ecology ◽

10.1093/oso/9780198835851.003.0002 ◽

2019 ◽

pp. 11-37

Author(s):

Gary G. Mittelbach ◽

Brian J. McGill

Keyword(s):

Species Richness ◽

Species Interactions ◽

Biological Diversity ◽

Spatial Scales ◽

Species Numbers ◽

Diversity Gradient ◽

Species Abundances ◽

Species Area ◽

Species Area Relationship ◽

The Relationship

This chapter examines how biodiversity, the variety of life, is distributed across the globe and within local communities. It begins by considering some of the challenges associated with assessing biological diversity at different spatial scales. Then, three of the best-studied patterns in species richness are examined in detail—the species–area relationship, the distribution of species abundances, and the relationship between productivity and species richness. The chapter concludes with a detailed exploration of the most dramatic of Earth’s biodiversity patterns—the latitudinal diversity gradient. The above patterns constitute much of what community ecology seeks to explain about nature. Their study provides a foundation from which to explore mechanisms of species interactions, and to understand the processes that drive variation in species numbers and their distribution.

Download Full-text

Do syntopic host species harbour similar symbiotic communities? The case ofChaetopterusspp. (Annelida: Chaetopteridae)

PeerJ ◽

10.7717/peerj.2930 ◽

2017 ◽

Vol 5 ◽

pp. e2930 ◽

Cited By ~ 6

Author(s):

Temir A. Britayev ◽

Elena Mekhova ◽

Yury Deart ◽

Daniel Martin

Keyword(s):

Species Richness ◽

Community Structure ◽

Host Species ◽

Interspecific Interactions ◽

Single Species ◽

Intraspecific Interactions ◽

Mean Intensity ◽

Species Dominance ◽

High Species Richness ◽

Symbiotic Community

To assess whether closely related host species harbour similar symbiotic communities, we studied two polychaetes,Chaetopterussp. (n = 11) andChaetopteruscf.appendiculatus(n = 83) living in soft sediments of Nhatrang Bay (South China Sea, Vietnam). The former harboured the porcellanid crabsPolyonyxcf.heokandPolyonyxsp., the pinnotherid crabTetriassp. and the tergipedid nudibranchPhestillasp. The latter harboured the polynoid polychaeteOphthalmonoe pettiboneae, the carapid fishOnuxodon fowleriand the porcellanid crabEulenaios cometes, all of which, exceptO. fowleri, seemed to be specialized symbionts. The species richness and mean intensity of the symbionts were higher inChaetopterussp. than inC.cf.appendiculatus(1.8 and 1.02 species and 3.0 and 1.05 individuals per host respectively). We suggest that the lower density ofChaetopterussp. may explain the higher number of associated symbionts observed, as well as the 100% prevalence (69.5% inC.cf.appenciculatus). MostChaetopterussp. harboured two symbiotic species, which was extremely rare inC.cf.appendiculatus, suggesting lower interspecific interactions in the former. The crab and nudibranch symbionts ofChaetopterussp. often shared a host and lived in pairs, thus partitioning resources. This led to the species coexisting in the tubes ofChaetopterussp., establishing a tightly packed community, indicating high species richness and mean intensity, together with a low species dominance. In contrast, the aggressive, strictly territorial species associated withC.cf.appendiculatusestablished a symbiotic community strongly dominated by single species and, thus, low species richness and mean intensity. Therefore, we suggest that interspecific interactions are determining species richness, intensity and dominance, while intraspecific interactions are influencing only intensity and abundance. It is possible that species composition may have influenced the differences in community structure observed. We hypothesize that both host species could originally be allopatric. The evolutionary specialization of the symbiotic communities would occur in separated geographical areas, while the posterior disappearance of the existing geographical barriers would lead to the overlapped distribution.

Download Full-text

The Habitat Amount Hypothesis implies negative effects of habitat fragmentation on species richness and occurrence

10.1101/2020.02.02.930784 ◽

2020 ◽

Author(s):

Santiago Saura

Keyword(s):

Species Richness ◽

Habitat Fragmentation ◽

Spatial Configuration ◽

Spatial Scales ◽

Conservation Strategies ◽

Negative Effects ◽

Habitat Amount ◽

Habitat Configuration ◽

Habitat Amount Hypothesis ◽

Individual Site

AbstractThe Habitat Amount Hypothesis (HAH) predicts that species richness, abundance or occurrence in a habitat site increases with the amount of habitat in the ‘local landscape’ defined by an appropriate distance around the site, with no distinct effects of the size of the habitat patch in which the site is located. It has been stated that a consequence of the HAH, if supported, would be that it is unnecessary to consider habitat configuration to predict or manage biodiversity patterns, and that conservation strategies should focus on habitat amount regardless of fragmentation. Here, I assume that the HAH holds and apply the HAH predictions to all habitat sites over entire landscapes that have the same amount of habitat but differ in habitat configuration. By doing so, I show that the HAH actually implies clearly negative effects of habitat fragmentation, and of other spatial configuration changes, on species richness, abundance or occurrence in all or many of the habitat sites in the landscape, and that these habitat configuration effects are distinct from those of habitat amount in the landscape. I further show that, contrary to current interpretations, the HAH is compatible with a steeper slope of the species-area relationship for fragmented than for continuous habitat, and with higher species richness or abundance for a single large patch than for several small patches with the same total area (SLOSS). This suggests the need to revise the ways in which the HAH has been interpreted and can be actually tested. The misinterpretation of the HAH has arisen from confounding and overlooking the differences in the spatial scales involved: the individual habitat site at which the HAH gives predictions, the local landscape around an individual site, and the landscapes or regions (with multiple habitat sites and different local landscapes) that need to be analysed and managed. The HAH has been erroneously viewed as negating or diminishing the relevance of fragmentation effects, while it actually supports the importance of habitat configuration for biodiversity. I conclude that, even in the cases where the HAH holds, habitat fragmentation and configuration are important for understanding and managing species distributions in the landscape.

Download Full-text

Species-area and network-area relationships in host–helminth interactions

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.3143 ◽

2021 ◽

Vol 288 (1947) ◽

Author(s):

Tad A. Dallas ◽

Pedro Jordano

Keyword(s):

Species Richness ◽

Trophic Interactions ◽

Species Interactions ◽

Geographical Area ◽

Species Interaction ◽

Helminth Parasites ◽

Scaling Relationship ◽

Theoretical Predictions ◽

Species Area ◽

Network Area

The scaling relationship observed between species richness and the geographical area sampled (i.e. the species-area relationship (SAR)) is a widely recognized macroecological relationship. Recently, this theory has been extended to trophic interactions, suggesting that geographical area may influence the structure of species interaction networks (i.e. network-area relationships (NARs)). Here, we use a global dataset of host–helminth parasite interactions to test existing predictions from macroecological theory. Scaling between single locations to the global host–helminth network by sequentially adding networks together, we find support that geographical area influences species richness and the number of species interactions in host–helminth networks. However, species-area slopes were larger for host species relative to their helminth parasites, counter to theoretical predictions. Lastly, host–helminth network modularity—capturing the tendency of the network to form into separate subcommunities—decreased with increasing area, also counter to theoretical predictions. Reconciling this disconnect between existing theory and observed SAR and NAR will provide insight into the spatial structuring of ecological networks, and help to refine theory to highlight the effects of network type, species distributional overlap, and the specificity of trophic interactions on NARs.

Download Full-text

A universal scaling method for biodiversity-ecosystem functioning relationships

10.1101/662783 ◽

2019 ◽

Cited By ~ 2

Author(s):

K.E. Barry ◽

G.A. Pinter ◽

J.W. Strini ◽

K. Yang ◽

I.G. Lauko ◽

...

Keyword(s):

Species Richness ◽

Biomass Production ◽

Ecosystem Functioning ◽

Spatial Scales ◽

Tropical Dry Forest ◽

Dry Forest ◽

Additional Species ◽

Spatial And Temporal Scales ◽

Natural Systems ◽

Species Area

SummaryGlobal biodiversity is declining at rates faster than at any other point in human history. Experimental manipulations of biodiversity at small spatial scales have demonstrated that communities with fewer species consistently produce less biomass than higher diversity communities. However, understanding how the global extinction crisis is likely to impact global ecosystem functioning will require applying these local and largely experimental findings to natural systems at substantially larger spatial and temporal scales. Here we propose that we can use two simple macroecological patterns – the species area curve and the biomass-area curve – to upscale the species richness-biomass relationship. We demonstrate that at local spatial scales, each additional species will contribute more to biomass production with increasing area sampled because the species-area curve saturates and the biomass-area curve increases monotonically. We use species-area and biomass-area curves from a Minnesota grassland and a Panamanian tropical dry forest to examine the species richness – biomass relationship at three and ten sampling extents, respectively. In both datasets, the observed relationship between biodiversity and biomass production at every sampling extent was predicted from simple species-area and biomass-area relationships. These findings suggest that macroecological patterns like the species-area curve underpin the scaling of biodiversity-ecosystem functioning research and can be used to predict these relationships at the global scales where they are relevant for species loss.

Download Full-text

Seascape connectivity exerts differing effects for fish assemblages in distinct habitats of the surf zones of ocean beaches

ICES Journal of Marine Science ◽

10.1093/icesjms/fsaa018 ◽

2020 ◽

Vol 77 (3) ◽

pp. 1033-1042

Author(s):

Jesse D Mosman ◽

Christopher J Henderson ◽

Andrew D Olds ◽

Ben L Gilby ◽

Thomas A Schlacher

Keyword(s):

Species Richness ◽

Indicator Species ◽

Surf Zone ◽

Fish Assemblages ◽

Spatial Configuration ◽

Spatial Scales ◽

Coastal Habitat ◽

Rocky Reefs ◽

Eastern Australia ◽

Management Approaches

Abstract Animals move throughout coastal seascapes to disperse, feed, and spawn, including the surf zones of ocean beaches. Yet, the influences of seascape context on surf-zone fish are largely unquantified. We sampled surf-zone fish assemblages with baited remote underwater video deployments at 25 beaches across 50 km of coastline in eastern Australia to determine if variation in the spatial configuration of broader coastal seascapes shapes fish assemblages in different surf-zone habitats. We show that surf zones are not homogenous fish habitats, with offshore bars and nearshore troughs having distinct fish assemblages, shaped by different environmental variables. Fish assemblages of offshore bars were characterized by greater species richness and a higher abundance of indicator species (as identified by Dufrene–Legendre indicator species analysis) when close to rocky reefs and estuaries. In contrast, fish assemblages of nearshore troughs were characterized by greater species richness and a higher abundance of indicator species when far from estuaries, and off wider beaches. Our results highlight the importance of seascape connectivity in structuring surf-zone fish assemblages. Consequently, management approaches need to more thoroughly quantify the effects of seascape connectivity over smaller spatial scales and consider surf zones as key components of broader coastal habitat mosaics.

Download Full-text

Richness and Composition of Oasis Bird Communities: Spatial Issues and Species–Area Relationships

The Auk ◽

10.1093/auk/119.2.533 ◽

2002 ◽

Vol 119 (2) ◽

pp. 533-539

Author(s):

Slaheddine Selmi ◽

Thierry Boulinier ◽

Robert Barbault

Keyword(s):

Species Richness ◽

Spatial Organization ◽

Spatial Configuration ◽

Spatial Location ◽

Oceanic Islands ◽

Local Communities ◽

Bird Communities ◽

Spatial Covariance ◽

Species Area ◽

The Relationship

Abstract We used data on breeding bird communities of the oases of southern Tunisia to investigate variation in species richness and composition among local communities in relation to spatial configuration of the oasis system and to assess significance of the relationship between oasis size and local richness. Oases could be grouped into three regional systems, namely littoral, saharan, and mountainous oases. We found that at the scale of the entire oasis system, species richness and species composition exhibited significant spatial autocorrelation. That result was consistent with our prediction that the particular spatial organization of oases may have led to regional differences in availability of potential colonizers and that higher species exchange within oasis zones than among oasis zones may have played an important role in shaping local communities. With regard to the species–area relationship, we thus found that a model accounting for spatial covariance was more parsimonious than a standard regression model not incorporating information on the spatial location of oases. Overall, oasis size was a good predictor of species richness, but results were sensitive to spatial scale at which the relationship was examined. Aside from oceanic islands and forest patches, oases may constitute interesting systems to study how regional processes affect local diversity.

Download Full-text

Energetic and ecological constraints on population density of reef fishes

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.2186 ◽

2016 ◽

Vol 283 (1823) ◽

pp. 20152186 ◽

Cited By ~ 19

Author(s):

D. R. Barneche ◽

M. Kulbicki ◽

S. R. Floeter ◽

A. M. Friedlander ◽

A. P. Allen

Keyword(s):

Species Richness ◽

Body Size ◽

Population Density ◽

Species Interactions ◽

Spatial Scales ◽

Small Body ◽

Reef Fishes ◽

Abundant Species ◽

Global Scale ◽

Ecological Constraints

Population ecology has classically focused on pairwise species interactions, hindering the description of general patterns and processes of population abundance at large spatial scales. Here we use the metabolic theory of ecology as a framework to formulate and test a model that yields predictions linking population density to the physiological constraints of body size and temperature on individual metabolism, and the ecological constraints of trophic structure and species richness on energy partitioning among species. Our model was tested by applying Bayesian quantile regression to a comprehensive reef-fish community database, from which we extracted density data for 5609 populations spread across 49 sites around the world. Our results indicate that population density declines markedly with increases in community species richness and that, after accounting for richness, energetic constraints are manifested most strongly for the most abundant species, which generally are of small body size and occupy lower trophic groups. Overall, our findings suggest that, at the global scale, factors associated with community species richness are the major drivers of variation in population density. Given that populations of species-rich tropical systems exhibit markedly lower maximum densities, they may be particularly susceptible to stochastic extinction.

Download Full-text