scholarly journals Small-scale variability of protistan planktonic communities relative to environmental pressures and biotic interactions at two adjacent coastal stations

2016 ◽  
Vol 548 ◽  
pp. 61-75 ◽  
Author(s):  
S Genitsaris ◽  
S Monchy ◽  
E Breton ◽  
E Lecuyer ◽  
U Christaki
Keyword(s):  
Biotic Interactions ◽  
Small Scale ◽  
Environmental Pressures ◽  
Planktonic Communities

Species associations of congeneric species in a tropical seasonal rain forest of China

2016 ◽  
Vol 32 (3) ◽  
pp. 201-212 ◽  
Author(s):  
Guoyu Lan ◽  
Yunbing Zhang ◽  
Fangliang He ◽  
Yuehua Hu ◽  
Hua Zhu ◽  
...  
Keyword(s):  
Species Interactions ◽  
Rain Forest ◽  
Biotic Interactions ◽  
Second Order ◽  
Small Scale ◽  
Order Effects ◽  
Congeneric Species ◽  
First Order ◽  
Large Trees ◽  
Tropical Seasonal Rain Forest

Abstract:In tropical plant communities with diverse species, many congeners are found to coexist. Do environment or biotic interactions structure the coexistence of congeners in tropical forest communities? In this paper, we aimed to disentangle the effect of environment (first-order effects) and species interactions (second-order effects) on the spatial distributions of tree species. We used a classification scheme and torus-translation to test the first-order interaction of 48 species from 17 genera in a fully mapped 20-ha dipterocarp tropical seasonal rain-forest plot in Xishuangbanna, south-west China. Then we used heterogeneous Poisson null models to reveal significant uni- and bivariate second-order interactions. The results demonstrated that (1) 34 of the 48 studied species showed a significant relation with at least one topographic variable. This confirmed that topographical heterogeneity is important for distribution of these congeners. Spatial segregation (36.6%) and partial overlap (34.8%) were the most common bivariate association types in Xishuangbanna plot, which indicated first-order effects (environment) were strong. (2) For small-scale associations, 51% saplings (1 to ≤ 5 cm) (68.8% for large trees with dbh > 5 cm) of the species showed non-significant associations. For large-scale associations, 61.6% saplings (81.2% for large trees) of the species showed non-significant associations. Lack of significant species interactions provides evidence for the unified neutral theory. In conclusion, both environment and biotic interactions structure congeneric species' coexistence in tropical seasonal rain forest in this region.

Information loss in the transition from life to death assemblages of foraminifera in back reef environments, Key Largo, Florida

1988 ◽  
Vol 62 (03) ◽  
pp. 399-410 ◽  
Author(s):  
Ronald E. Martin ◽  
Ramil C. Wright
Keyword(s):  
Cluster Analysis ◽  
Biotic Interactions ◽  
Information Loss ◽  
Small Scale ◽  
Time Averaging ◽  
Back Reef ◽  
Death Assemblages ◽  
Key Largo ◽  
Vegetation Samples ◽  
Marine Angiosperm

Despite numerous distributional studies of foraminifera in modern shallow-water carbonate environments, information loss and taphonomic bias in the transition from life to death assemblages of foraminifera in these environments have not previously been examined in detail. Surface sediment and vegetation samples were collected along six nearshore traverses and one traverse across the back reef lagoon off Key Largo, Florida. Living foraminifera are found in abundance on algae and the marine angiosperm,Thalassia testudinum, while foraminifera in sediment assemblages are represented primarily by empty tests. Q-mode cluster analysis of living assemblages onThalassiadelineates inshore (depth 0.4–2.7 m) and offshore (3.0–9.0 m) back reef biofacies. Calcareous imperforate (suborder Miliolina) species thrive in quiet waters of the inshore biofacies, in which biotic interactions appear to be the prime factor in determining small-scale species distributions of living foraminifera. Fragile species are most susceptible to test destruction, and, therefore, sediment assemblages are dominated by more robust forms (e.g.,Archaias angulatus, Valvulina oviedoiana, thick-walled species ofQuinqueloculina).Water turbulence primarily determines species composition of living populations of the offshore biofacies. These assemblages are dominated by the calcareous perforate (suborder Rotaliina) speciesPlanorbulina acervalisandRosalina bahamaensis. These species resist transport by encrustingThalassiablades and having a test which fits flush with grass blades, respectively. However, sediment assemblages of the offshore biofacies are also dominated by typical inshore, robust species (Archaias angulatus, thick-walled miliolids). Thus, inshore and offshore biofacies are not readily differentiated by Q-mode cluster analysis of sediment assemblages. Robust species are wide ranging and often abundant in sediment because of differential preservation and time-averaging of sediment assemblages. The resultant taphonomic bias may interfere with paleoecologic interpretations concerning intensity of water energy and distance from shore.

scholarly journals Ecological relevance of abundant and rare taxa in a high-diverse elastic hypersaline microbial mat, using a small-scale sampling

2021 ◽  
Author(s):  
Laura Espinosa-Asuar ◽  
Camila Monroy ◽  
David Madrigal-Trejo ◽  
Marisol Navarro ◽  
Jazmin Sanchez ◽  
...  
Keyword(s):  
Microbial Diversity ◽  
Chihuahuan Desert ◽  
Biotic Interactions ◽  
16S Rrna Gene Sequencing ◽  
Biological Properties ◽  
Microbial Mat ◽  
Small Scale ◽  
Rrna Gene ◽  
Rare Taxa ◽  
Rare Biosphere

We evaluated the microbial diversity and metabolomic signatures of a hypersaline elastic microbial mat from Cuatro Cienegas Basin (CCB) in the Chihuahuan Desert of Coahuila, Mexico. We collected ten samples within a small scale (1.5-meters transect) and found a high microbial diversity through NGS-based ITS and 16S rRNA gene sequencing. A very low number of taxa were abundant and shared between all sites, whereas the rare biosphere was more phylogenetically diverse (FPD index) and phylogenetically disperse (PSC index) than the abundant taxa for both analyzed libraries. In regard to potential biotic interactions (Pearson analysis), there were more positive correlations than negative. We also found a distinctive metabolomic signature for each sample and were able to tentatively annotate several classes of compounds with relevant biological properties. Together, these results reveal cohesive, diverse and fluctuating microbial communities, where abundant and rare taxa appear to have different ecological roles.

scholarly journals Co-occurring morphologically distinct algae support a diverse associated fauna in the intertidal zone of Araçá Bay, Brazil

2018 ◽  
Vol 18 (1) ◽  
Author(s):  
Edson A. Vieira ◽  
Heloísa Romeu Filgueiras ◽  
Marília Bueno ◽  
Fosca Pedini Pereira Leite ◽  
Gustavo Muniz Dias
Keyword(s):  
Rocky Shore ◽  
Biotic Interactions ◽  
Light Limitation ◽  
Small Scale ◽  
Rocky Shores ◽  
Associated Fauna ◽  
Close Relationship ◽  
Algal Host ◽  
Species Tolerance ◽  
Terrestrial Insects

Abstract Species diversity is regulated by historical, neutral and niche processes, with species tolerance, dispersal and productivity guiding diversity at larger scales, while habitat heterogeneity and biotic interactions acts in smaller scales. In rocky shores, several organisms provide secondary substrates for mobile fauna, with macroalgae being the most abundant and diverse ones. The patchiness promoted by different macroalgae hosts enhances small-scale heterogeneity and may increase and maintain the diversity of the mobile organisms, since there is a close relationship between the associated fauna and its hosts. In this study we selected three morphologically different macroalgae that coexist in the same rocky shore height in the Araçá Bay, an area under the threat of the nearby harbor expansion, and evaluated the fauna associated to each algal host. Even under similar abiotic pressure (same rocky shore height), the associated fauna of each algal host varied in number and composition, revealing a close relationship. The poorly branched foliose Ulva lactuca sustained a lower density of organisms and was dominated by isopods, while the heavily branched turf and Bostrychietum community showed a high density of organisms, with a dominance of peracarid crustaceans and annelids on the turf and more resistant groups, such as bivalves, acaris and terrestrial insects on the Bostrychietum. Previous studies in the Araçá Bay already revealed a large spatial heterogeneity in the processes and sessile organisms distribution, and here we highlight that this heterogeneity can be observed in an even smaller scale, with different algal hosts mediating the turnover of species in a scale of centimeters and meters, resulting in diversity maintenance of the associated fauna. Since the harbor expansion may prevent the occurrence of macroalgae as a result of light limitation by suspended platforms, we may expect not only a decrease in algal cover but also in the total diversity of the associated fauna in the Araçá Bay.

scholarly journals The Effects of Habitat Heterogeneity at Distinct Spatial Scales on Hard-Bottom-Associated Communities

Diversity ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 39 ◽  
Author(s):  
Fabiane Gallucci ◽  
Ronaldo A. Christofoletti ◽  
Gustavo Fonseca ◽  
Gustavo M. Dias
Keyword(s):  
Habitat Heterogeneity ◽  
Rocky Shore ◽  
Spatial Scales ◽  
Benthic Communities ◽  
Biotic Interactions ◽  
Habitat Diversity ◽  
Small Scale ◽  
Β Diversity ◽  
Biological Substrate ◽  
Mangrove Roots

For marine benthic communities, environmental heterogeneity at small spatial scales are mostly due to biologically produced habitat heterogeneity and biotic interactions, while at larger spatial scales environmental factors may prevails over biotic features. In this study, we investigated how community structure and β-diversity of hard-bottom-associated meio- and macrofauna varied in relation to small-scale (cm–m) changes in biological substrate (an algae “turf” dominated by the macroalgae Gelidium sp., the macroalgae Caulerpa racemosa and the sponge Hymeniacidon heliophile) in a rocky shore and in relation to larger-scale (10’s m) changes in environmental conditions of the same biological substrate (the macroalgae Bostrychia sp) in different habitats (rocky shore vs. mangrove roots). Results showed that both substrate identity and the surrounding environment were important in structuring the smaller-sized meiofauna, particularly the nematode assemblages, whereas the larger and more motile macrofauna was influenced only by larger-scale changes in the surrounding ecosystem. This implies that the macrofauna explores the environment in a larger spatial scale compared to the meiofauna, suggesting that effects of spatial heterogeneity on communities are dependent on organism size and mobility. Changes in taxa composition between environments and substrates highlight the importance of habitat diversity at different scales for maintaining the diversity of the associated fauna.

scholarly journals From Surface to Subsurface: Diversity, Composition, and Abundance of Sessile and Endolithic Bacterial, Archaeal, and Eukaryotic Communities in Sand, Clay and Rock Substrates in the Laurentians (Quebec, Canada)

2022 ◽  
Vol 10 (1) ◽  
pp. 129
Author(s):  
Julia Meyer ◽  
Sheri Zakhary ◽  
Marie Larocque ◽  
Cassandre S. Lazar
Keyword(s):  
Biotic Interactions ◽  
Vertical Movement ◽  
Shallow Subsurface ◽  
Aquifer Systems ◽  
Geological Formation ◽  
Systematic Understanding ◽  
Microbial Groups ◽  
Terrestrial Subsurface ◽  
Do So ◽  
Planktonic Communities

Microbial communities play an important role in shallow terrestrial subsurface ecosystems. Most studies of this habitat have focused on planktonic communities that are found in the groundwater of aquifer systems and only target specific microbial groups. Therefore, a systematic understanding of the processes that govern the assembly of endolithic and sessile communities is still missing. This study aims to understand the effect of depth and biotic factors on these communities, to better unravel their origins and to compare their composition with the communities detected in groundwater. To do so, we collected samples from two profiles (~0–50 m) in aquifer sites in the Laurentians (Quebec, Canada), performed DNA extractions and Illumina sequencing. The results suggest that changes in geological material characteristics with depth represent a strong ecological and phylogenetical filter for most archaeal and bacterial communities. Additionally, the vertical movement of water from the surface plays a major role in shallow subsurface microbial assembly processes. Furthermore, biotic interactions between bacteria and eukaryotes were mostly positive which may indicate cooperative or mutualistic potential associations, such as cross-feeding and/or syntrophic relationships in the terrestrial subsurface. Our results also point toward the importance of sampling both the geological formation and groundwater when it comes to studying its overall microbiology.

Information loss in the transition from life to death assemblages of foraminifera in back reef environments, Key Largo, Florida

1988 ◽  
Vol 62 (3) ◽  
pp. 399-410 ◽  
Author(s):  
Ronald E. Martin ◽  
Ramil C. Wright
Keyword(s):  
Cluster Analysis ◽  
Biotic Interactions ◽  
Information Loss ◽  
Small Scale ◽  
Time Averaging ◽  
Back Reef ◽  
Death Assemblages ◽  
Key Largo ◽  
Vegetation Samples ◽  
Marine Angiosperm

Despite numerous distributional studies of foraminifera in modern shallow-water carbonate environments, information loss and taphonomic bias in the transition from life to death assemblages of foraminifera in these environments have not previously been examined in detail. Surface sediment and vegetation samples were collected along six nearshore traverses and one traverse across the back reef lagoon off Key Largo, Florida. Living foraminifera are found in abundance on algae and the marine angiosperm, Thalassia testudinum, while foraminifera in sediment assemblages are represented primarily by empty tests. Q-mode cluster analysis of living assemblages on Thalassia delineates inshore (depth 0.4–2.7 m) and offshore (3.0–9.0 m) back reef biofacies. Calcareous imperforate (suborder Miliolina) species thrive in quiet waters of the inshore biofacies, in which biotic interactions appear to be the prime factor in determining small-scale species distributions of living foraminifera. Fragile species are most susceptible to test destruction, and, therefore, sediment assemblages are dominated by more robust forms (e.g., Archaias angulatus, Valvulina oviedoiana, thick-walled species of Quinqueloculina).Water turbulence primarily determines species composition of living populations of the offshore biofacies. These assemblages are dominated by the calcareous perforate (suborder Rotaliina) species Planorbulina acervalis and Rosalina bahamaensis. These species resist transport by encrusting Thalassia blades and having a test which fits flush with grass blades, respectively. However, sediment assemblages of the offshore biofacies are also dominated by typical inshore, robust species (Archaias angulatus, thick-walled miliolids). Thus, inshore and offshore biofacies are not readily differentiated by Q-mode cluster analysis of sediment assemblages. Robust species are wide ranging and often abundant in sediment because of differential preservation and time-averaging of sediment assemblages. The resultant taphonomic bias may interfere with paleoecologic interpretations concerning intensity of water energy and distance from shore.

Reasons to strike first

2019 ◽  
Vol 42 ◽  
Author(s):  
William Buckner ◽  
Luke Glowacki
Keyword(s):  
Intergroup Conflict ◽  
Small Scale

Abstract De Dreu and Gross predict that attackers will have more difficulty winning conflicts than defenders. As their analysis is presumed to capture the dynamics of decentralized conflict, we consider how their framework compares with ethnographic evidence from small-scale societies, as well as chimpanzee patterns of intergroup conflict. In these contexts, attackers have significantly more success in conflict than predicted by De Dreu and Gross's model. We discuss the possible reasons for this disparity.

Exploring Coronal Structures with SOHO

2000 ◽  
Vol 179 ◽  
pp. 403-406
Author(s):  
M. Karovska ◽  
B. Wood ◽  
J. Chen ◽  
J. Cook ◽  
R. Howard
Keyword(s):  
Solar Corona ◽  
Image Enhancement ◽  
Coronal Mass Ejections ◽  
Dynamical Evolution ◽  
Small Scale ◽  
Low Contrast ◽  
Contrast Structures ◽  
Scale Structures ◽  
Small Scale Structures ◽  
Coronal Structures

AbstractWe applied advanced image enhancement techniques to explore in detail the characteristics of the small-scale structures and/or the low contrast structures in several Coronal Mass Ejections (CMEs) observed by SOHO. We highlight here the results from our studies of the morphology and dynamical evolution of CME structures in the solar corona using two instruments on board SOHO: LASCO and EIT.

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