scholarly journals Coexistence patterns and diversity in a trait-based metacommunity on an environmental gradient

Author(s):  
Mozzamil Mohammed ◽  
Bernd Blasius ◽  
Alexey Ryabov

AbstractThe dynamics of trait-based metacommunities have attracted much attention, but not much is known about how dispersal and spatial environmental variability mutually interact with each other to drive coexistence patterns and diversity. Here, we present a spatially explicit model of competition for two essential resources in a metacommunity on a one-dimensional environmental gradient. We find that both the strength of dispersal and the range of spatial environmental variability affect coexistence patterns, spatial structure, trait distribution, and local and regional diversity. Without dispersal, species are sorted according to their optimal growth conditions on the gradient. With the onset of dispersal, source-sink effects are initiated, which increases the effects of environmental filtering and interspecific competition and generates trait lumping, so that only a few species from an environment-defined trait range can survive. Interestingly, for very large dispersal rates, species distributions become spatially homogeneous, but nevertheless two species at the extreme ends of the trade-off curve can coexist for large environmental variability. Local species richness follows a classic hump-shaped dependence on dispersal rate, while local and regional diversity exhibit a pronounced peak for intermediate values of the environmental variability. Our findings provide important insights into the factors that shape the structure of trait-based metacommunities.

2021 ◽  
Author(s):  
Mozzamil Mohammed ◽  
Bernd Blasius ◽  
Alexey Ryabov

Abstract The dynamics of trait-based metacommunities have attracted much attention, but not much is known about how dispersal and spatial environmental variability mutually interact with each other to drive coexistence patterns and diversity. Here, we present a spatially-explicit model of resource competition in a metacommunity on a one- dimensional environmental gradient. We find that both the strength of dispersal and the range of spatial environmental variability affect coexistence patterns, spatial structure, trait distribution and local and regional diversity. Without dispersal, species are sorted according to their optimal growth conditions on the gradient. With the onset of dispersal source-sink effects are initiated, which increases the effects of environmental filtering and interspecific competition and generates trait lumping, so that only a few species from an environment-defined trait range can survive. Interestingly, for very large dispersal rates the system becomes spatially homogeneous, but nevertheless two species at the extreme ends of the trait-off curve can coexist for large environmental variability. Local species richness follows a classic hump-shaped dependence on dispersal rate, while local and regional diversity exhibit a pronounced peak for intermediate values of the environmental variability. Our findings provide important insights into the factors that shape the structure of trait-based metacommunities.


2021 ◽  
Author(s):  
Mozzamil Mohammed ◽  
Bernd Blasius ◽  
Alexey Ryabov

The dynamics of trait-based metacommunities have attracted much attention, but not much is known about how dispersal and environmental variability mutually interact with each other to drive coexistence mechanisms and diversity patterns. Here, we present a spatially-explicit model of resource competition in a metacommunity on a one-dimensional environmental gradient and analyse the joint influence of dispersal and environmental variability on coexistence mechanisms, spatial structure, trait distribution and local and regional diversity. We find that without dispersal, species are sorted according to their optimal position on the gradient, but with the onset of dispersal source-sink effects are initiated. Thereby, the dispersal rate and the range of spatial environmental variability strongly affect the competition outcomes, composition, and diversity. That is, at low dispersal rates the number of surviving species increases with the spatial environmental variability. Increasing dispersal rates generates trait lumping and strengthens environmental filtering so that only a few dominant species can survive. Interestingly, for very large dispersal rates the system becomes spatially homogeneous, but nevertheless two specialists at the extreme ends of the trait-off curve can coexist. Global species richness depends in an intricate manner on dispersal strength and resource variability, with a classic hump-shaped dependence of diversity on dispersal rate, but also a pronounced peak of global diversity for intermediate values of resource variability. Our findings thus provide important insights into the factors that shape metacommunity structure and promote coexistence and about how spatial environmental variability can lead to different competition outcomes in metacommunities.


2014 ◽  
Vol 30 (4) ◽  
pp. 335-346 ◽  
Author(s):  
Salman Abdo Al-Shami ◽  
Che Salmah Md Rawi ◽  
Abu Hassan Ahmad ◽  
Madziatul Rosemahanie Madrus ◽  
Khalid AL Mutairi

Abstract:We used aquatic macro-invertebrates as a model to investigate the relationship between the regional species richness (RSR) and local species richness (LSR) in Peninsular Malaysia. A total of 38 streams (local scale) in seven catchments (regional scale), were sampled for aquatic macro-invertebrates. Eleven environmental variables (i.e. pH, DO, velocity, temperature, width, depth, TSS, BOD, COD, ammonia and canopy cover) were measured to assess their importance for local species richness. The average species richness was 34.9 species per region and the average abundance was 1380 individual per region. The highest number of species was 41, while the lowest species richness was 31. We applied local-regional richness regression models to explore the nature of the RSR–LSR relationship and then used variation partitioning to determine the relative importance of RSR and environmental conditions on LSR. We found a linear RSR–LSR relationship, which indicates unsaturated communities for macro-invertebrates in Malaysian streams and absence of local control with strong effects of regional processes. Variation in LSR explained by RSR was 43%, while the variation fraction in LSR explained by environmental conditions was low (2%) and not significant. We conclude that the variation in LSR is mainly controlled by the regional diversity pool (i.e. RSR) for aquatic macro-invertebrates in Peninsular Malaysia. However, weak effects of environmental conditions may reflect relatively low variability in the habitat among investigated streams. Further studies at larger scales, and involving different regions in this area, will be useful to draw comprehensive conclusions about determinants of local species diversity for stream invertebrates.


Flora ◽  
2021 ◽  
pp. 151868
Author(s):  
Karlo G. Guidoni-Martins ◽  
Leandro Maracahipes ◽  
Adriano S. Melo ◽  
Marcus V. Cianciaruso

1992 ◽  
Vol 12 (9) ◽  
pp. 3827-3833 ◽  
Author(s):  
T H Adams ◽  
W A Hide ◽  
L N Yager ◽  
B N Lee

In contrast to many other cases in microbial development, Aspergillus nidulans conidiophore production initiates primarily as a programmed part of the life cycle rather than as a response to nutrient deprivation. Mutations in the acoD locus result in "fluffy" colonies that appear to grow faster than the wild type and proliferate as undifferentiated masses of vegetative cells. We show that unlike wild-type strains, acoD deletion mutants are unable to make conidiophores under optimal growth conditions but can be induced to conidiate when growth is nutritionally limited. The requirement for acoD in conidiophore development occurs prior to activation of brlA, a primary regulator of development. The acoD transcript is present both in vegetative hyphae prior to developmental induction and in developing cultures. However, the effects of acoD mutations are detectable only after developmental induction. We propose that acoD activity is primarily controlled at the posttranscriptional level and that it is required to direct developmentally specific changes that bring about growth inhibition and activation of brlA expression to result in conidiophore development.


2004 ◽  
Vol 94 (2) ◽  
pp. 111-121 ◽  
Author(s):  
P.A.V. Borges ◽  
V.K. Brown

AbstractThe arthropod species richness of pastures in three Azorean islands was used to examine the relationship between local and regional species richness over two years. Two groups of arthropods, spiders and sucking insects, representing two functionally different but common groups of pasture invertebrates were investigated. The local–regional species richness relationship was assessed over relatively fine scales: quadrats (= local scale) and within pastures (= regional scale). Mean plot species richness was used as a measure of local species richness (= α diversity) and regional species richness was estimated at the pasture level (= γ diversity) with the ‘first-order-Jackknife’ estimator. Three related issues were addressed: (i) the role of estimated regional species richness and variables operating at the local scale (vegetation structure and diversity) in determining local species richness; (ii) quantification of the relative contributions of α and β diversity to regional diversity using additive partitioning; and (iii) the occurrence of consistent patterns in different years by analysing independently between-year data. Species assemblages of spiders were saturated at the local scale (similar local species richness and increasing β-diversity in richer regions) and were more dependent on vegetational structure than regional species richness. Sucking insect herbivores, by contrast, exhibited a linear relationship between local and regional species richness, consistent with the proportional sampling model. The patterns were consistent between years. These results imply that for spiders local processes are important, with assemblages in a particular patch being constrained by habitat structure. In contrast, for sucking insects, local processes may be insignificant in structuring communities.


2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Lyudmila P. Trenozhnikova ◽  
Almagul K. Khasenova ◽  
Assya S. Balgimbaeva ◽  
Galina B. Fedorova ◽  
Genrikh S. Katrukha ◽  
...  

We describe the actinomycete strain IMV-70 isolated from the soils of Kazakhstan, which produces potent antibiotics with high levels of antibacterial activity. After the research of its morphological, chemotaxonomic, and cultural characteristics, the strain with potential to be developed further as a novel class of antibiotics with chemotherapeutics potential was identified asStreptomycessp. IMV-70. In the process of fermentation, the strainStreptomycesspp. IMV-70 produces the antibiotic no. 70, which was isolated from the culture broth by extraction with organic solvents. Antibiotic compound no. 70 was purified and separated into individual components by HPLC, TLC, and column chromatography methods. The main component of the compound is the antibiotic 70-A, which was found to be identical to the peptolide etamycin A. Two other antibiotics 70-B and 70-C have never been described and therefore are new antibiotics. The physical-chemical and biological characteristics of these preparations were described and further researched. Determination of the optimal growth conditions to cultivate actinomycete-producer strain IMV-70 and development of methods to isolate, purify, and accumulate preparations of the new antibiotic no. 70 enable us to research further the potential of this new class of antibiotics.


2004 ◽  
Vol 17 (1) ◽  
pp. 1-13 ◽  
Author(s):  
M. Veith ◽  
S. Wulffraat ◽  
J. Kosuch ◽  
G. Hallmann ◽  
H.-W. Henkel ◽  
...  

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