scholarly journals More than the sum of the parts: annual partitioning within spatial guilds underpins community regulation

2018 ◽  
Vol 285 (1883) ◽  
pp. 20180659 ◽  
Author(s):  
A. E. Magurran ◽  
P. A. Henderson
Keyword(s):  
Estuarine Fish ◽  
Modular Organization ◽  
Assemblage Composition ◽  
Community Regulation ◽  
As Species ◽  
Composition And Structure ◽  
Species Abundances ◽  
Annual Population ◽  
Population Sizes ◽  
Positive Covariance

To withstand the pressures of a rapidly changing world, resilient ecosystems should exhibit compensatory dynamics, including uncorrelated temporal shifts in population sizes. The observation that diversity is maintained through time in many systems is evidence that communities are indeed regulated and stabilized, yet empirical observations suggest that positive covariance in species abundances is widespread. This paradox could be resolved if communities are composed of a number of ecologically relevant sub-units in which the members compete for resources, but whose abundances fluctuate independently. Such modular organization could explain community regulation, even when the community as a whole appears synchronized. To test this hypothesis, we quantified temporal synchronicity in annual population abundances within spatial guilds in an estuarine fish assemblage that has been monitored for 36 years. We detected independent fluctuations in annual abundances within guilds. By contrast, the assemblage as a whole exhibited temporal synchronicity—an outcome linked to the dynamics of guild dominants, which were synchronized with each other. These findings underline the importance of modularity in explaining community regulation and highlight the need to protect assemblage composition and structure as well as species richness.

Environmental variation and habitat separation among small mammals

1989 ◽  
Vol 67 (1) ◽  
pp. 8-13 ◽  
Author(s):  
William L. Vickery ◽  
Stuart L. Iverson ◽  
Steve Mihok ◽  
Bill Schwartz
Keyword(s):  
Population Density ◽  
Habitat Use ◽  
Small Mammals ◽  
Environmental Variables ◽  
Dominant Species ◽  
Species Abundances ◽  
Principal Factors ◽  
Population Sizes ◽  
Positive Covariance ◽  
Habitat Separation

Habitat use and population density of five species of forest small mammals were monitored by annual spring snap-trap censuses at Pinawa, Manitoba, over 14 years. Population sizes were positively correlated among species and showed no evidence of density-dependent effects. Species were habitat selectors. Habitat use by species did not vary among years. Habitat separation between the dominant species was not correlated with environmental variables or with population size. We suggest that habitat selection and positive covariance among species abundances are the principal factors characterizing the dynamics of this community.

scholarly journals Macro- and mesoscale pattern interdependencies in complex networks

2019 ◽  
Vol 16 (159) ◽  
pp. 20190553 ◽  
Author(s):  
M. J. Palazzi ◽  
J. Borge-Holthoefer ◽  
C. J. Tessone ◽  
A. Solé-Ribalta
Keyword(s):  
Complex Networks ◽  
Empirical Evidence ◽  
Structural Properties ◽  
Modular Architecture ◽  
Modular Networks ◽  
As Species ◽  
Species Abundances ◽  
Organizational Patterns ◽  
Natural Combination ◽  
The Relationship

Identifying and explaining the structure of complex networks at different scales has become an important problem across disciplines. At the mesoscale, modular architecture has attracted most of the attention. At the macroscale, other arrangements—e.g. nestedness or core–periphery—have been studied in parallel, but to a much lesser extent. However, empirical evidence increasingly suggests that characterizing a network with a unique pattern typology may be too simplistic, since a system can integrate properties from distinct organizations at different scales. Here, we explore the relationship between some of these different organizational patterns: two at the mesoscale (modularity and in-block nestedness); and one at the macroscale (nestedness). We show experimentally and analytically that nestedness imposes bounds to modularity, with exact analytical results in idealized scenarios. Specifically, we show that nestedness and modularity are interdependent. Furthermore, we analytically evidence that in-block nestedness provides a natural combination between nested and modular networks, taking structural properties of both. Far from a mere theoretical exercise, understanding the boundaries that discriminate each architecture is fundamental, to the extent that modularity and nestedness are known to place heavy dynamical effects on processes, such as species abundances and stability in ecology.

scholarly journals Composition and structure of fish assemblage from Passa Cinco stream, Corumbataí river sub-basin, SP, Brazil

2012 ◽  
Vol 72 (1) ◽  
pp. 87-96
Author(s):  
AL Carmassi ◽  
G Rondineli ◽  
FC Ferreira ◽  
FMS Braga
Keyword(s):  
Species Distribution ◽  
Fish Assemblage ◽  
Altitudinal Gradient ◽  
Habitat Diversity ◽  
Important Species ◽  
Assemblage Composition ◽  
Gill Nets ◽  
Composition And Structure ◽  
Significant Difference ◽  
Richness Index

The aim of this work was to determine the composition of the fish assemblage of Passa Cinco stream and verify changes in their structure on the altitudinal gradient. Six samples were performed at five different sites in Passa Cinco stream (from the headwater, at order two, to its mouth, at order six), using an electric fishery equipment and gill nets in May, July, September and November of 2005 and January and March of 2006. The indices of Shannon's diversity, Pielou's evenness and Margalef's richness were quantified separately considering the different fishery equipment (nets versus electric fishery equipment). An ANOVA was used to compare samples collected in relation to values of abundance, diversity, evenness and richness. The representativeness of the species was summarised by their average values of abundance and weight. We captured 5082 individuals distributed into 61 species. We observed a trend of increasing diversity, richness and evenness of species from site 1 to 3, with further decrease in sites 4 and 5. The values found for habitat diversity also followed this pattern. Significant differences were found for all three indices considering the electric fishery samples. For individuals caught with nets, only the richness index showed a significant difference. Characidium aff. zebra was an important species in the headwater and transition sites and Hypostomus strigaticeps in middle-lower course sites. Despite the small extension of the Passa Cinco stream, environments structurally well defined were evidenced by the species distribution and assemblage composition along the gradient.

Species and genus richness and assemblage composition of stream caddisflies (Insecta: Trichoptera) vary with latitude in mountain rainforest of Argentina

2019 ◽  
Vol 70 (5) ◽  
pp. 687
Author(s):  
Edgardo J. I. Pero ◽  
Paola A. Rueda Martín ◽  
María C. Reynaga
Keyword(s):  
Latitudinal Gradient ◽  
Aquatic Insect ◽  
Latitudinal Gradients ◽  
Mountain Forest ◽  
Low Latitude ◽  
Study Region ◽  
Assemblage Composition ◽  
Composition And Structure ◽  
Genus Richness ◽  
Rank Abundance

Evidence found in results of studies of latitudinal gradients of benthic macroinvertebrate diversity is variable. This study analysed how species and genus richness and the composition of caddisfly assemblages (Insecta: Trichoptera) vary in Argentinean mountain forest through a latitudinal gradient from 22 to 28°S. Qualitative and quantitative data from 20 stream sites were compared. Assemblage richness and composition were analysed by comparing linear regressions, rank–abundance (RA) curves and non-metric multidimensional scaling (nMDS). Taxonomic richness increased from high to low latitude. RA curves showed changes in assemblage composition and structure across the latitudinal gradient. The nMDS revealed that the composition of the assemblages also changed along the latitudinal gradient. The patterns are similar to those observed in plants and vertebrates from the study region. The results are of particular note because a latitudinal gradient of aquatic insect diversity has rarely been observed in a narrow range.

Conditional effects of aquatic insects of small tributaries on mainstream assemblages: position within drainage network matters

2014 ◽  
Vol 71 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Silvia Vendruscolo Milesi ◽  
Adriano Sanches Melo
Keyword(s):  
Spatial Heterogeneity ◽  
Aquatic Insects ◽  
Drainage Network ◽  
Stream Networks ◽  
Assemblage Composition ◽  
Nested Subsets ◽  
Aquatic Fauna ◽  
Bottom Substrate ◽  
Conditional Effects ◽  
Composition And Structure

Tributaries may affect fauna in a mainstream by changing bottom substrate and increasing spatial heterogeneity. Additionally, we hypothesized that fauna in the mainstream may be affected by drifting migrants from tributaries. In nine stream networks, we sampled a similar microhabitat immediately upstream and downstream of two confluences. In each network, one confluence was located in the network centre and one in the periphery, and they were distinguished by low and high ratios of tributary size, respectively. We assessed whether the aquatic fauna at sites downstream from confluences was species-richer, distinct in composition and structure, and whether it included the fauna of upstream sites. We found that richness, rarefied richness, and abundance at downstream sites were not higher than at their upstream counterparts. Faunas at downstream sites were not nested subsets of those at upstream sites. Macroinvertebrate assemblage composition and structure differed between downstream and upstream sites in the peripheral confluences (high tributary to mainstream (T:M) ratios), but not in central confluences (low T:M ratios). Thus, effects of small tributaries on receiving mainstreams are dependent on the T:M ratio.

scholarly journals Populations and assemblages living on the edge: dung beetles responses to forests-pasture ecotones

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e6148 ◽  
Author(s):  
Ana Paola Martínez-Falcón ◽  
Gustavo A. Zurita ◽  
Ilse J. Ortega-Martínez ◽  
Claudia E. Moreno
Keyword(s):  
Edge Effects ◽  
Functional Divergence ◽  
Species Abundance ◽  
Dung Beetle ◽  
Dung Beetles ◽  
Insect Biodiversity ◽  
As Species ◽  
Functional Richness ◽  
Species Abundances ◽  
Managed Landscapes

Edge effects alter insect biodiversity in several ways. However, we still have a limited understanding on simultaneous responses of ecological populations and assemblages to ecotones, especially in human modified landscapes. We analyze edge effects on dung beetle populations and assemblages between livestock pastures and native temperate forests (Juniperusand pine-oak forests (POFs)) to describe how species abundances and assemblage parameters respond to edge effects through gradients in forest-pasture ecotones. InJuniperusforest 13 species avoided the ecotones: six species showed greater abundance in forest interior and seven in pasturelands, while the other two species had a neutral response to the edge. In a different way, in POF we found five species avoiding the edge (four with greater abundance in pastures and only one in forest), two species had a neutral response, and two showed a unimodal pattern of abundance near to the edge. At the assemblage level edge effects are masked, as species richness, diversity, functional richness, functional evenness, and compositional incidence dissimilarity did not vary along forest-pasture ecotones. However, total abundance and functional divergence showed higher values in pastures in one of the two sampling localities. Also, assemblage similarity based on species’ abundance showed a peak near to the edge in POF. We propose that conservation efforts in human-managed landscapes should focus on mitigating current and delayed edge effects. Ecotone management will be crucial in livestock dominated landscapes to conserve regional biodiversity and the environmental services carried out by dung beetles.

scholarly journals Historic collections as a tool for assessing the global pollinator crisis

2018 ◽  
Author(s):  
I. Bartomeus ◽  
J.R. Stavert ◽  
D. Ward ◽  
O. Aguado
Keyword(s):  
Species Interactions ◽  
Pollination Services ◽  
Specimen Collection ◽  
As Species ◽  
Geographical Regions ◽  
The Status ◽  
Species Abundances ◽  
Collection Data ◽  
Pollinator Declines

AbstractThere is increasing concern about the decline of pollinators worldwide. However, despite reports that pollinator declines are widespread, data are scarce and often geographically and taxonomically biased. These biases limit robust inference about any potential pollinator crisis. Non-structured and opportunistic historical specimen collection data provide the only source of historical information which can serve as a baseline for identifying pollinator declines. Specimens historically collected and preserved in museums not only provide information on where and when species were collected, but also contain other ecological information such as species interactions and morphological traits. Here, we provide a synthesis of how researchers have used historical data to identify long-term changes in biodiversity, species abundances, morphology and pollination services. Despite recent advances, we show that information on the status and trends of most pollinators is absent, but we highlight opportunities and limitations to progress the assessment of pollinator declines globally. Finally, we demonstrate different approaches to analysing museum collection data using two contrasting case studies from distinct geographical regions (New Zealand and Spain) for which long-term pollinator declines have never been assessed. There is immense potential for museum specimens to play a central role in assessing the extent of the global pollination crisis.

scholarly journals Community composition, beta diversity and structure of high altitude grasslands along an altitudinal gradient in southeastern Brazil

2020 ◽  
Vol 68 (3) ◽  
Author(s):  
Prímula Viana Campos ◽  
Pedro Manuel Villa ◽  
Carlos Ernesto Gonçalves Reynaud Schaefer ◽  
Jaquelina Alves Nunes ◽  
Stefan Porembski ◽  
...  
Keyword(s):  
Community Composition ◽  
Indicator Species ◽  
Beta Diversity ◽  
Altitudinal Gradient ◽  
Southeastern Brazil ◽  
Indicator Species Analysis ◽  
Composition And Structure ◽  
Species Analysis ◽  
Species Abundances ◽  
High Altitude Grasslands

Introduction: Studies on how the altitudinal gradient determines community composition and structure in tropical high altitude grasslands are limited. Objective: To evaluate the plant community composition and structure and their relationship with altitude and soil properties along an altitudinal gradient of three granitic rocky outcrops at the Serra do Brigadeiro State Park, Minas Gerais, in southeastern Brazil. Methods: In each selected site, 100 plots of 1 × 1 m were established, totalizing 300 plots in the study area. We compared floristic composition, relative coverage and abundance among sites. We performed beta diversity analysis. We also performed an indicator species analysis and a canonical correlation analysis to investigate possible relations between abiotic (soil and altitude) and biotic (indicator species abundances) variables. Results: We sampled a total of 9 276 individuals belonging to 39 families and 102 species. Significant differences were observed among sites regarding composition, abundance and coverage. The indicator species analysis revealed that 57 species (55.88 %) were indicators. The distribution of indicator species abundances was correlated with environmental variables. Conclusions: It was observed that altitude and soil play an important role in controlling community composition and structure, beta diversity and species distribution in the highland grasslands studied.

scholarly journals Plant Functional Traits on Tropical Ultramafic Habitats Affected by Fire and Mining: Insights for Reclamation

Diversity ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 248
Author(s):  
Celestino Quintela-Sabarís ◽  
Michel-Pierre Faucon ◽  
Rimi Repin ◽  
John B. Sugau ◽  
Reuben Nilus ◽  
...  
Keyword(s):  
Functional Traits ◽  
Plant Cover ◽  
Lateral Spreading ◽  
Growth Strategy ◽  
Ultramafic Soils ◽  
As Species ◽  
First Choice ◽  
Species Abundances ◽  
Number Of Stems ◽  
In Fire

Biodiversity-rich tropical ultramafic areas are currently being impacted by land clearing and particularly by mine activities. The reclamation of ultramafic degraded areas requires a knowledge of pioneer plant species. The objective of this study is to highlight the functional traits of plants that colonize ultramafic areas after disturbance by fire or mining activities. This information will allow trait-assisted selection of candidate species for reclamation. Fifteen plots were established on ultramafic soils in Sabah (Borneo, Malaysia) disturbed by recurrent fires (FIRE plots) or by soil excavation and quarrying (MINE plots). In each plot, soil samples were collected and plant cover as well as species abundances were estimated. Fifteen functional traits related to revegetation, nutrient improvement, or Ni phytomining were measured in sampled plants. Vegetation of both FIRE and MINE plots was dominated by perennials with lateral spreading capacity (mainly by rhizomes). Plant communities displayed a conservative growth strategy, which is an adaptation to low nutrient availability on ultramafic soils. Plant height was higher in FIRE than in MINE plots, whereas the number of stems per plant was higher in MINE plots. Perennial plants with lateral spreading capacity and a conservative growth strategy would be the first choice for the reclamation of ultramafic degraded areas. Additional notes for increasing nutrient cycling, managing competition, and implementing of Ni-phytomining are also provided.

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