scholarly journals Divergent responses of β‐diversity among organism groups to a strong environmental gradient

Ecosphere ◽  
2016 ◽  
Vol 7 (10) ◽  
Author(s):  
Micael Jonsson ◽  
Tord Snäll ◽  
Johan Asplund ◽  
Karina E. Clemmensen ◽  
Anders Dahlberg ◽  
...  
Keyword(s):  
Environmental Gradient ◽  
Β Diversity

scholarly journals Diferenciación florística en afloramientos calizos del sur de México y el centro de Brasil: un enfoque de diversidad beta

2019 ◽  
Vol 84 ◽  
pp. 45
Author(s):  
Eduardo A. Pérez García ◽  
Anderson C. Sevilha ◽  
Jorge A. Meave ◽  
Aldicir Scariot
Keyword(s):  
Environmental Gradient ◽  
Distance Effect ◽  
Floristic Composition ◽  
Spatial Arrangement ◽  
Central Brazil ◽  
Β Diversity ◽  
Structural Variables ◽  
Order Of Magnitude ◽  
Edaphic Gradient ◽  
Study Sites

We studied the spatial arrangement of floristic diversity in two systems of limestone outcrops, located in two distant Neotropical sites: the region of Nizanda (S Mexico) and the Paranã Valley (Central Brazil). We addressed the question whether their vegetation could display a similar zonation, and we explored the relative effects of distance and an environmental gradient on α-, β- and γ-diversities. The limestone outcrops at both sites are similar in size and in elevation, but strongly differ in between-outcrop distance by an order of magnitude. At each study site three individual limestone outcrops were selected; in each of them three plant communities along the edaphic gradient were distinguished (a xerophytic scrub and two tropical dry forests types, one of which had a more xeric character than the other), and sampled for structural variables and floristic composition in 100-m2 plots. At both study sites, structural variables responded similarly to the edaphic gradient. Species density was larger in Nizanda for both α- and γ-diversity, but the largest value of β-diversity was obtained in Paranã. The edaphic gradient produced larger mean β-diversity values than the simple distance effect, with the interaction of both factors resulting in an even larger β-diversity. Classification analyses by site showed larger floristic similarities between the two xerophytic communities than those existing between them and the more mesic forests. The spatial arrangement of diversity showed that both α- and γ-diversity were smaller for the xerophytic communities. As hypothesized, the more extreme changes in community physiognomy were associated with larger β-diversity values

Patterns in diversity and composition of the microbenthos of subarctic intertidal beaches with different morphodynamics

2020 ◽  
Vol 648 ◽  
pp. 19-38
Author(s):  
AI Azovsky ◽  
YA Mazei ◽  
MA Saburova ◽  
PV Sapozhnikov
Keyword(s):  
Species Abundance ◽  
Abundance Ratio ◽  
Wave Action ◽  
Coarse Grained ◽  
Sediment Properties ◽  
Β Diversity ◽  
Α Diversity ◽  
Wide Range ◽  
Similar Mode ◽  
Abundance And Diversity

Diversity and composition of benthic diatom algae and ciliates were studied at several beaches along the White and Barents seas: from highly exposed, reflective beaches with coarse-grained sands to sheltered, dissipative silty-sandy flats. For diatoms, the epipelic to epipsammic species abundance ratio was significantly correlated with the beach index and mean particle size, while neither α-diversity measures nor mean cell length were related to beach properties. In contrast, most of the characteristics of ciliate assemblages (diversity, total abundance and biomass, mean individual weight and percentage of karyorelictids) demonstrated a strong correlation to beach properties, remaining low at exposed beaches but increasing sharply in more sheltered conditions. β-diversity did not correlate with beach properties for either diatoms or ciliates. We suggest that wave action and sediment properties are the main drivers controlling the diversity and composition of the intertidal microbenthos. Diatoms and ciliates, however, demonstrated divergent response to these factors. Epipelic and epipsammic diatoms exhibited 2 different strategies to adapt to their environments and therefore were complementarily distributed along the environmental gradient and compensated for each other in diversity. Most ciliates demonstrated a similar mode of habitat selection but differed in their degree of tolerance. Euryporal (including mesoporal) species were relatively tolerant to wave action and therefore occurred under a wide range of beach conditions, though their abundance and diversity were highest in fine, relatively stable sediments on sheltered beaches, whereas the specific interstitial (i.e. genuine microporal) species were mostly restricted to only these habitats.

scholarly journals Fish community shifts along a strong fluvial environmental gradient revealed by eDNA metabarcoding

2021 ◽  
Author(s):  
Erik García‐Machado ◽  
Martin Laporte ◽  
Eric Normandeau ◽  
Cecilia Hernández ◽  
Guillaume Côté ◽  
...  
Keyword(s):  
Fish Community ◽  
Environmental Gradient ◽  
Community Shifts

scholarly journals Effect of hay type on cecal and fecal microbiome and fermentation parameters in horses

2020 ◽  
Author(s):  
Rachel J Sorensen ◽  
James S Drouillard ◽  
Teresa L Douthit ◽  
Qinghong Ran ◽  
Douglas G Marthaler ◽  
...  
Keyword(s):  
Fixed Effects ◽  
Volatile Fatty Acids ◽  
Random Effect ◽  
Alpha Diversity ◽  
Sampling Location ◽  
Rrna Gene ◽  
Illumina Hiseq ◽  
Fecal Microbiome ◽  
Β Diversity ◽  
Fermentation Parameters

Abstract The effect of hay type on the microbiome of the equine gastrointestinal tract is relatively unexplored. Our objective was to characterize the cecal and fecal microbiome of mature horses consuming alfalfa or Smooth Bromegrass (brome) hay. Six cecally cannulated horses were used in a split plot design run as a crossover in 2 periods. Whole plot treatment was ad libitum access to brome or alfalfa hay fed over two 21-d acclimation periods with subplots of sampling location (cecum and rectum) and sampling hour. Each acclimation period was followed by a 24-h collection period where cecal and fecal samples were collected every 3 h for analysis of pH and volatile fatty acids (VFA). Fecal and cecal samples were pooled and sent to a commercial lab (MR DNA, Shallowater, TX) for amplification of the V4 region of the 16S rRNA gene and sequenced using Illumina HiSeq. Main effects of hay on VFA, pH, and taxonomic abundances were analyzed using the MIXED procedure of SAS 9.4 with fixed effects of hay, hour, location, period, all possible interactions and random effect of horse. Alpha and β diversity were analyzed using the R Dame package. Horses fed alfalfa had greater fecal than cecal pH (P ≤ 0.05) whereas horses fed brome had greater cecal than fecal pH (P ≤ 0.05). Regardless of hay type, total volatile fatty acid (VFA) concentrations were greater (P ≤ 0.05) in the cecum than in feces, and alfalfa resulted in greater (P ≤ 0.05) VFA concentrations than brome in both sampling locations. Alpha diversity was greater (P ≤ 0.05) in fecal compared to cecal samples. Microbial community structure within each sampling location and hay type differed from one another (P ≤ 0.05). Bacteroidetes were greater (P ≤ 0.05) in the cecum compared to the rectum, regardless of hay type. Firmicutes and Firmicutes:Bacteroidetes were greater (P ≤ 0.05) in the feces compared to cecal samples of alfalfa-fed horses. In all, fermentation parameters and bacterial abundances were impacted by hay type and sampling location in the hindgut.

scholarly journals Adaptive Divergence under Gene Flow along an Environmental Gradient in Two Coexisting Stickleback Species

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 435
Author(s):  
Thijs M. P. Bal ◽  
Alejandro Llanos-Garrido ◽  
Anurag Chaturvedi ◽  
Io Verdonck ◽  
Bart Hellemans ◽  
...  
Keyword(s):  
Gene Flow ◽  
Brackish Water ◽  
Environmental Gradient ◽  
Spatial Scales ◽  
Morphological Differentiation ◽  
Genotyping By Sequencing ◽  
Adaptive Divergence ◽  
Linkage Groups ◽  
Closely Related Species ◽  
Genomic Patterns

There is a general and solid theoretical framework to explain how the interplay between natural selection and gene flow affects local adaptation. Yet, to what extent coexisting closely related species evolve collectively or show distinctive evolutionary responses remains a fundamental question. To address this, we studied the population genetic structure and morphological differentiation of sympatric three-spined and nine-spined stickleback. We conducted genotyping-by-sequencing and morphological trait characterisation using 24 individuals of each species from four lowland brackish water (LBW), four lowland freshwater (LFW) and three upland freshwater (UFW) sites in Belgium and the Netherlands. This combination of sites allowed us to contrast populations from isolated but environmentally similar locations (LFW vs. UFW), isolated but environmentally heterogeneous locations (LBW vs. UFW), and well-connected but environmentally heterogenous locations (LBW vs. LFW). Overall, both species showed comparable levels of genetic diversity and neutral genetic differentiation. However, for all three spatial scales, signatures of morphological and genomic adaptive divergence were substantially stronger among populations of the three-spined stickleback than among populations of the nine-spined stickleback. Furthermore, most outlier SNPs in the two species were associated with local freshwater sites. The few outlier SNPs that were associated with the split between brackish water and freshwater populations were located on one linkage group in three-spined stickleback and two linkage groups in nine-spined stickleback. We conclude that while both species show congruent evolutionary and genomic patterns of divergent selection, both species differ in the magnitude of their response to selection regardless of the geographical and environmental context.

scholarly journals Oral and Intravenous Iron Therapy Differentially Alter the On- and Off-Tumor Microbiota in Anemic Colorectal Cancer Patients

Cancers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1341
Author(s):  
Oliver Phipps ◽  
Hafid O. Al-Hassi ◽  
Mohammed N. Quraishi ◽  
Edward A. Dickson ◽  
Jonathan Segal ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Ferrous Sulphate ◽  
Intravenous Iron ◽  
Oral Iron ◽  
Iron Therapy ◽  
Deficiency Anemia ◽  
Ferric Carboxymaltose ◽  
Β Diversity ◽  
Post Surgery ◽  
Intravenous Iron Therapy

Iron deficiency anemia is a common complication of colorectal cancer and may require iron therapy. Oral iron can increase the iron available to gut bacteria and may alter the colonic microbiota. We performed an intervention study to compare oral and intravenous iron therapy on the colonic tumor-associated (on-tumor) and paired non-tumor-associated adjacent (off-tumor) microbiota. Anemic patients with colorectal adenocarcinoma received either oral ferrous sulphate (n = 16) or intravenous ferric carboxymaltose (n = 24). On- and off-tumor biopsies were obtained post-surgery and microbial profiling was performed using 16S ribosomal RNA analysis. Off-tumor α- and β-diversity were significantly different between iron treatment groups. No differences in on-tumor diversity were observed. Off-tumor microbiota of oral iron-treated patients showed higher abundances of the orders Clostridiales, Cytophagales, and Anaeroplasmatales compared to intravenous iron-treated patients. The on-tumor microbiota was enriched with the orders Lactobacillales and Alteromonadales in the oral and intravenous iron groups, respectively. The on- and off-tumor microbiota associated with intravenous iron-treated patients infers increased abundances of enzymes involved in iron sequestration and anti-inflammatory/oncogenic metabolite production, compared to oral iron-treated patients. Collectively, this suggests that intravenous iron may be a more appropriate therapy to limit adverse microbial outcomes compared to oral iron.

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