Clumpy coexistence in phytoplankton: the role of functional similarity in community assembly

AbstractEmergent neutrality (EN) suggests that species must be sufficiently similar or sufficiently different in their niches to avoid interspecific competition. Such a scenario results in a multimodal distribution of species abundance along the niche axis (e.g., body size), namely clumps. From this perspective, species within clumps should behave in a quasi-neutral state, and their abundance will show stochastic fluctuations. Plankton is an excellent model system for developing and testing ecological theories, especially those related to size structure and species coexistence. We tested EN predictions using the phytoplankton community along the course of a tropical river considering (i) body size structure, (ii) functional clustering of species in terms of morphology-based functional groups (MBFG), and (iii) the functional similarity among species with respect to their functional traits. Considering body size as the main niche axis, two main clumps (clump I and II) were detected in different stretches of the river and remained conspicuous through time. The clump I comprised medium-sized species mainly from the MBFG IV, while the clump II included large-bodied species from the groups V and VI. Pairwise differences in species biovolume correlated with species functional redundancy when the whole species pool was considered, but not among species within the same clump. Within-clump functional distinctiveness was positively correlated with species biovolume considering both seasons, and also at the upper course. These results suggest that species within clumps behave in a quasi-neutral state, but even minor shifts in trait composition may affect their biovolume. In sum, our findings point that EN belongs to the plausible mechanisms explaining community assembly in river ecosystems.

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The Role of Dimensional Distinctiveness in Children's and Adults' Artifact Categorization

Psychological Science ◽

10.1111/j.0956-7976.2005.00794.x ◽

2005 ◽

Vol 16 (2) ◽

pp. 137-144 ◽

Cited By ~ 18

Author(s):

Rubi Hammer ◽

Gil Diesendruck

Keyword(s):

Preschool Children ◽

Contextual Factors ◽

A Priori ◽

Functional Similarity ◽

Second Stage ◽

Functional Dimension

There are conflicting results as to whether preschool children categorize artifacts on the basis of physical or functional similarity. The present study investigated the effect of the relative distinctiveness of these dimensions in children's categorization. In a physical-distinctive condition, preschool children and adults were initially asked to categorize computer-animated artifacts whose physical appearances were more distinctive than their functions. In a function-distinctive condition, the functional dimension of objects was more distinctive than their physical appearances. Both conditions included a second stage of categorization in which both dimensions were equally distinctive. Participants in a control condition performed only this stage of categorization. Adults in all conditions and stages consistently categorized by functional similarity. In contrast, children's categorization was affected by the relative distinctiveness of the dimensions. Children may not have a priori specific beliefs about how to categorize novel artifacts, and thus may be more susceptible to contextual factors.

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Stochastic Assembly Leads to Alternative Communities with Distinct Functions in a Bioreactor Microbial Community

mBio ◽

10.1128/mbio.00584-12 ◽

2013 ◽

Vol 4 (2) ◽

Cited By ~ 128

Author(s):

Jizhong Zhou ◽

Wenzong Liu ◽

Ye Deng ◽

Yi-Huei Jiang ◽

Kai Xue ◽

...

Keyword(s):

Community Structure ◽

Microbial Community ◽

Microbial Diversity ◽

Microbial Community Structure ◽

Community Assembly ◽

Ecosystem Functioning ◽

Dominant Role ◽

Microbial Biodiversity ◽

Stochastic Assembly

ABSTRACTThe processes and mechanisms of community assembly and its relationships to community functioning are central issues in ecology. Both deterministic and stochastic factors play important roles in shaping community composition and structure, but the connection between community assembly and ecosystem functioning remains elusive, especially in microbial communities. Here, we used microbial electrolysis cell reactors as a model system to examine the roles of stochastic assembly in determining microbial community structure and functions. Under identical environmental conditions with the same source community, ecological drift (i.e., initial stochastic colonization) and subsequent biotic interactions created dramatically different communities with little overlap among 14 identical reactors, indicating that stochastic assembly played dominant roles in determining microbial community structure. Neutral community modeling analysis revealed that deterministic factors also played significant roles in shaping microbial community structure in these reactors. Most importantly, the newly formed communities differed substantially in community functions (e.g., H2production), which showed strong linkages to community structure. This study is the first to demonstrate that stochastic assembly plays a dominant role in determining not only community structure but also ecosystem functions. Elucidating the links among community assembly, biodiversity, and ecosystem functioning is critical to understanding ecosystem functioning, biodiversity preservation, and ecosystem management.IMPORTANCEMicroorganisms are the most diverse group of life known on earth. Although it is well documented that microbial natural biodiversity is extremely high, it is not clear why such high diversity is generated and maintained. Numerous studies have established the roles of niche-based deterministic factors (e.g., pH, temperature, and salt) in shaping microbial biodiversity, the importance of stochastic processes in generating microbial biodiversity is rarely appreciated. Moreover, while microorganisms mediate many ecosystem processes, the relationship between microbial diversity and ecosystem functioning remains largely elusive. Using a well-controlled laboratory system, this study provides empirical support for the dominant role of stochastic assembly in creating variations of microbial diversity and the first explicit evidence for the critical role of community assembly in influencing ecosystem functioning. The results presented in this study represent important contributions to the understanding of the mechanisms, especially stochastic processes, involved in shaping microbial biodiversity.

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What matters most - Role of environment, arrival order and population fitness in invaded community assembly

Acta Oecologica ◽

10.1016/j.actao.2018.10.006 ◽

2018 ◽

Vol 93 ◽

pp. 56-64

Author(s):

Achyut Kumar Banerjee ◽

Chiranjib Medda ◽

Sabyasachi Bhattacharya ◽

Anjana Dewanji

Keyword(s):

Community Assembly ◽

Population Fitness ◽

What Matters

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Deterministic Selection Dominates Microbial Community Assembly in Termite Mounds Across a Large Spatial Area

10.21203/rs.3.rs-34782/v1 ◽

2020 ◽

Author(s):

Qing-Lin Chen ◽

Hang-Wei Hu ◽

Zhen-Zhen Yan ◽

Chao-Yu Li ◽

Bao-Anh Thi Nguyen ◽

...

Keyword(s):

Microbial Community ◽

Stochastic Processes ◽

Microbial Communities ◽

Fungal Community ◽

Community Assembly ◽

Distance Decay ◽

Termite Mounds ◽

Deterministic Processes ◽

Microbial Community Assembly

Abstract Background: Termites are ubiquitous insects in tropical and subtropical habitats, where they construct massive mounds from soil, their saliva and excreta. Termite mounds harbor an enormous amount of microbial inhabitants, which regulate multiple ecosystem functions such as mitigating methane emissions and increasing ecosystem resistance to climate change. However, we lack a mechanistic understanding about the role of termite mounds in modulating the microbial community assembly processes, which are essential to unravel the biological interactions of soil fauna and microorganisms, the major components of soil food webs. We conducted a large-scale survey across a >1500 km transect in northern Australia to investigate biogeographical patterns of bacterial and fungal community in 134 termite mounds and the relative importance of deterministic versus stochastic processes in microbial community assembly. Results: Microbial alpha (number of phylotypes) and beta (changes in bacterial and fungal community composition) significantly differed between termite mounds and surrounding soils. Microbial communities in termite mounds exhibited a significant distance-decay pattern, and fungal communities had a stronger distance-decay relationship (slope = -1.91) than bacteria (slope = -0.21). Based on the neutral community model (fitness < 0.7) and normalized stochasticity ratio index (NST) with a value below the 50% boundary point, deterministic selection, rather than stochastic forces, predominated the microbial community assembly in termite mounds. Deterministic processes exhibited significantly weaker impacts on bacteria (NST = 45.23%) than on fungi (NST = 33.72%), probably due to the wider habitat niche breadth and higher potential migration rate of bacteria. The abundance of antibiotic resistance genes (ARGs) was negatively correlated with bacterial/fungal biomass ratios, indicating that ARG content might be an important biotic factor that drove the biogeographic pattern of microbial communities in termite mounds. Conclusions: Deterministic processes play a more important role than stochastic processes in shaping the microbial community assembly in termite mounds, an unique habitat ubiquitously distributed in tropical and subtropical ecosystems. An improved understanding of the biogeographic patterns of microorganisms in termite mounds is crucial to decipher the role of soil faunal activities in shaping microbial community assembly, with implications for their mediated ecosystems functions and services.

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The role of temperature and dispersal in moss-microarthropod community assembly after a catastrophic event

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2012.0241 ◽

2012 ◽

Vol 367 (1605) ◽

pp. 3042-3049 ◽

Cited By ~ 11

Author(s):

Giselle Perdomo ◽

Paul Sunnucks ◽

Ross M. Thompson

Keyword(s):

Climate Change ◽

Community Assembly ◽

Size Structure ◽

Landscape Scale ◽

Model Systems ◽

Habitat Isolation ◽

Catastrophic Event ◽

Extreme Climatic Events ◽

Effects Of Temperature

There is a clear crisis in the maintenance of biodiversity. It has been generated by a multitude of factors, notably habitat loss, now compounded by the effects of climate change. Predicted changes in climate include increased severity and frequency of extreme climatic events. To manage landscapes, an understanding of the processes that allow recovery from these extreme events is required. Understanding these landscape-scale processes of community assembly and disassembly is hindered by the large scales at which they operate. Model systems provide a means of studying landscape scale processes at tractable scales. Here, we assess the combined effects of temperature and habitat-patch isolation on assembly of naturally diverse moss microarthropod communities after a high-temperature event. We show that community assembly depends on temperature and on degree of habitat isolation. Heated communities were heavily dominated in abundance by two species, one of them relatively large. The resulting size-structure is unlike that seen in the field. Community composition in habitat fragments appears also to have been influenced by the source pool of recolonizing fauna. Our results highlight the value of dispersal in disturbed landscapes and the potential for habitat connectivity to buffer communities from the effects of climate change.

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The role of phylogeny in desert rodent community assembly

Journal of Animal Ecology ◽

10.1111/j.1365-2656.2012.01962.x ◽

2012 ◽

Vol 81 (2) ◽

pp. 307-309 ◽

Cited By ~ 2

Author(s):

James H. Brown

Keyword(s):

Community Assembly ◽

Desert Rodent ◽

Rodent Community

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Role of suprachiasmatic nuclei in circadian and light-entrained behavioral rhythms of lizards

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.2000.279.6.r2121 ◽

2000 ◽

Vol 279 (6) ◽

pp. R2121-R2131 ◽

Cited By ~ 11

Author(s):

Cristiano Bertolucci ◽

Valeria Anna Sovrano ◽

Maria Chiara Magnone ◽

Augusto Foà

Keyword(s):

Circadian Rhythms ◽

Constant Temperature ◽

Locomotor Behavior ◽

Functional Similarity ◽

Daily Rhythm ◽

Constant Darkness ◽

Suprachiasmatic Nuclei ◽

Podarcis Sicula ◽

Behavioral Rhythms

To establish whether the suprachiasmatic nuclei (SCN) of the Ruin lizard ( Podarcis sicula) play a role in entrainment of circadian rhythms to light, we examined the effects of exposure to 24-h light-dark (LD) cycles on the locomotor behavior of lizards with SCN lesions. Lizards became arrhythmic in response to complete SCN lesion under constant temperature and constant darkness (DD), and they remained arrhythmic after exposure to LD cycles. Remnants of SCN tissue in other lesioned lizards were sufficient to warrant entrainment to LD cycles. Hence, the SCN of Ruin lizards are essential both to maintain locomotor rhythmicity and to mediate entrainment of these rhythms to light. We also asked whether light causes expression of Fos-like immunoreactivity (Fos-LI) in the SCN. Under LD cycles, the SCN express a daily rhythm in Fos-LI. Because Fos-LI is undetectable in DD, the rhythm seen in LD cycles is caused by light. We further showed that unilateral SCN lesions in DD induce dramatic period changes. Altogether, the present data support the existence of a strong functional similarity between the SCN of lizards and the SCN of mammals.

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