Niche Concept Research Articles

Preniche as missing link of the metastatic niche concept explaining organ-preferential metastasis of malignant tumors and the type of metastatic disease

Here we attempt to supplement the metastatic niche concept with a stage of "preniche" that determines the site of development of a premetastatic niche and of a subsequent metastasis. The "preniche" includes all cellular and molecular events in the site of a prospective metastasis preceding the entrance of myeloid progenitor cells. The "preniche" integrates an activation of vascular endothelium of the microcirculatory vessels of target organs in the site of a future metastasis under conditions of chronic persistent productive inflammation that can be induced by cytokines from the primary tumor and independently of it. The endothelium activation is responsible for adhesion and clustering of the recruited myeloid progenitor cells and also for the retention of cells of malignant tumors. The preniche easily arises in organs enriched with organ-specific macrophages (lungs, liver, brain, etc.) where the endothelium is predisposed for intensive recruiting of myeloid progenitor cells of macrophages, especially under conditions of inflammation. Introduction of the "preniche" concept allows us to avoid difficulties associated with the development of the metastatic niche concept, especially concerning the problem of organ-preferential localization of metastases, and to make some predictions for experimental verification and potential approaches for preventing metastasizing in some oncologic patients.

Positive interactions in ecology: filling the fundamental niche

The role of negative interactions in shaping ecological communities and the realized niches of species has been a focus of considerable research for at least decades. Traditionally, the discrepancy between the size of the fundamental and realized niche of a species was attributed to the effect of negative interactions, such that the realized niche is always smaller than the fundamental niche. However, in the last decade, a series of studies have highlighted the important role that positive interactions played in shaping the structure of communities. This renewed interest in positive interactions has led to a reconsideration of the niche concept. Specifically, some investigators have suggested that positive interactions can lead the realized niche of a species to be larger than its fundamental niche. Here, we show that although positive interactions can counteract the effects of negative interactions and possibly modify the realized niche of a species, the realized niche of a species can never be larger than the fundamental niche.

On the Distinctively Human: Two Perspectives on the Evolution of Language and Conscious Mind

In this paper, two alternative naturalistic standpoints on the relations between language, human consciousness and social life are contrasted. The first, dubbed “intrinsic naturalism,” is advocated among others by the realist philosopher John Searle; it starts with intrinsic intentionality and consciousness emerging from the brain, explains language as an outgrowth of consciousness and ends with institutional reality being created by language‐use. That standpoint leans on what may be described as the standard interpretation of Darwinian evolution. The other type of naturalism, in contrast, making use of the concept of evolutionary niches, suggests that the search for the explanatory mechanisms of language and consciousness should begin with the human community (of social action), because that is the cultural niche for everything distinctively human to evolve, including language and human consciousness.

An ecological analysis of competition among US communities

We apply the ecological concept of the organization's niche pioneered by John Freeman and Mike Hannan to the study of geographic communities. We define a community's market niche by the ties linking a community to the industries on which it depends for growth. We then hypothesize that the extent to which a community's market niche is occupied by other communities is a source of constraint and opportunity depending on the geographical locations of the communities that occupy the same market niche. Geographically distant communities occupying similar market niches are hypothesized to experience primarily constraint arising from competition for opportunities of exchange. Geographically proximate communities occupying similar market niches are hypothesized to face constraint arising from competition for exchange opportunities, as well as opportunity arising from access to valuable resources associated with the existence of similar others. Empirical analyses of firm foundings and exits across US communities support these hypotheses. Implications of our findings for ecological research on the niche and for the literature on communities are discussed.

Teaching natural history at the Museum of Vertebrate Zoology

AbstractDuring its centennial celebrations in 2008, the Museum of Vertebrate Zoology (MVZ) at the University of California, Berkeley paid homage to its founding director, Joseph Grinnell. Recognized as a leading scientific institution, the MVZ managed to grow throughout the twentieth century, a period often characterized by the decline of natural history. To understand how and why research flourished at the MVZ, this paper looks closely at Grinnell's undergraduate course, the Natural History of the Vertebrates (NHV). Taught by MVZ affiliates since 1914, the NHV offers an important window on Grinnell's approach and legacy. This paper argues that the NHV contributed to the MVZ's long-term success by acting as, first, a gateway to natural history; second, a vector for the MVZ's research programme; and third, a shared faculty responsibility. Grinnell's significance in the history of science is understated, in part because his writing style de-emphasized the importance of his theoretical contributions, including his development of the niche concept, his emphasis on population thinking and geographic isolation in studies of evolution, and his effort to integrate speciation questions and genetics. Studying the NHV highlights these contributions because Grinnell freely communicated his ideas to his students. An analysis of Grinnell's course material shows that his theoretical and methodological approach pre-dated the evolutionary synthesis and inspired natural-history research throughout the past century.

A ‘WalMartization’ of Religion? The Ecological Impact of Megachurches on the Local and Extra-Local Religious Economy

This study explores the impact megachurches have on local and extra-local congregations. Arguing that the two commonly held theories concerning the effect of megachurches on local congregations—that they are either harmful because they undercut local competition, or are beneficial because they increase local competition—are under-specified, we add the concept of religious niches to an organizational ecology model to predict how megachurches will differentially impact local congregations of various affiliation. Following new methodological directions charted by Blanchard et al. (Soc Forces 86(4):1591–1620, 2008 ), we test how the presence of megachurches differentially impacts congregational change rates among Catholics, Mainline Protestants, Conservative Protestants and three disaggregated Conservative Protestant sub-groups—Evangelical, Pentecostal and Fundamentalists, using county-level data from the 1990 and 2000 Churches and Church Membership datasets and megachurch data from the Database of Megachurches in the US. We find support for the variable impact of megachurches on local congregations in differing niches. For local congregations in dissimilar niches the presence of megachurches seems to be beneficial, whereas for local congregations inhabiting similar niches the presence of megachurches seems to be harmful. In addition to the local impact of megachurches, we find that they also have an impact upon the vitality of congregations in neighboring counties.

Community assembly and diversification in Indo-Pacific coral reef fishes.

Theories of species coexistence have played a central role in ecology and evolutionary studies of the origin and maintenance of biodiversity in highly diverse communities. The concept of niche and associated theories predict that competition for available ecological space leads to a ceiling in species richness that influences further diversification patterns. By contrast, the neutral theory supports that speciation is stochastic and diversity independent. We examined the phylogenetic community structure and diversification rates in three families and 14 sites within coral reef fish communities from the Indian and Pacific oceans. Using the phylogenetic relationships among 157 species estimated with 2300 bp of mitochondrial DNA, we tested predictions in terms of species coexistence from the neutral and niche theories. At the regional scale, our findings suggest that phylogenetic community structure shifts during community assembly to a pattern of dispersion as a consequence of allopatric speciation in recent times but overall, variations in diversification rates did not relate with sea level changes. At the local scale, the phylogenetic community structure is consistent with a neutral model of community assembly since no departure from a random sorting of species was observed. The present results support a neutral model of community assembly as a consequence of the stochastic and unpredictable nature of coral reefs favoring generalist and sedentary species competing for living space rather than trophic resources. As a consequence, the observed decrease in diversification rates may be seen as the result of a limited supply of living space as expected in a finite island model.

The vascular niche: home for normal and malignant hematopoietic stem cells

Hematopoietic stem cells (HSCs) are uniquely capable of self-renewal and provision of all of the mature elements of the blood and immune system throughout the lifetime of an individual. HSC self-renewal is regulated by both intrinsic mechanisms and extrinsic signals mediated via specialized microenvironments or 'niches' wherein HSCs reside. HSCs have been shown to reside in close association with bone marrow (BM) osteoblasts in the endosteal niche and also in proximity to BM sinusoidal vessels. An unresolved question surrounds whether the endosteal and vascular niches provide synchronous or redundant regulation of HSC fate or whether these niches provide wholly unique regulatory functions. Furthermore, while some aspects of the mechanisms through which osteoblasts regulate HSC fate have been defined, the mechanisms through which the vascular niche regulates HSC fate remain obscure. Here, we summarize the anatomic and functional basis supporting the concept of an HSC vascular niche as well as the precise function of endothelial cells, perivascular cells and stromal cells within the niche in regulating HSC fate. Lastly, we will highlight the role of the vascular niche in regulating leukemic stem cell fate in vivo.

Bone marrow‐derived endothelial and hematopoietic precursors cells enhance the metastasis of colon cancer in an orthotopic murine model

We have read with great interest the article by Shinagawa et al.1 In their study, they evaluated transplantation of the KM12SM human colon cancer cell line mixed with mesenchymal stem cells (MSCs) into the spleen.They reported a significantly greater number of liver metastases at 4 weeks with the cell mixture than with the transplantation of KM12SM cells alone. Additionally, MSCs surrounding the tumour were functionally incorporated into the stroma of the orthotopic colon tumour and expressed carcinoma-associated fibroblast markers. This manuscript prompted us to analyze the relevance of the murine model. To induce liver metastasis, a human colon cancer line (LS174) was injected into the spleen of nude mice. First, we characterized the bone marrow-derived cell (BMDC) population by fluorescence-activated cell sorting isolated on green mice C57 BL/6-Tg obtained after a density gradient. The population contained 30% of BM-derived endothelial precursor cells and derived haematopoietic precursor cells that expressed CD 133. At day 0, we injected BMDCs or PBS into the tail veins of tumor-bearing mice. At day 38, the injection of BMDCs enhanced the metastatic process in our model of liver metastasis with a number of micro or macrometastases in 56% of the BMDC group (n = 16) versus 20% in the PBS group (n = 20), p < 0.05. Immunofluorescent staining of cut liver specimens has demonstrated that BMDCs labelled with Green fluorescent protein (GFP) always localized to the tumour invasion front and colocalized with endothelial cells (Fig. 1). Migration of BMDCs to the stroma of a metastatic liver tumor (*): GFP-labeled BMDCs are localized to the tumor invasion front (a) and colocalized with endothelial cells (CD31 labeling in red) (b). (c) Merge (green and red). There is increasing evidence that BMDCs participate in the tumour microenvironment and metastatic progression,2-5 possibly by previous modification of the metastatic site by the BM-derived precursor cell before tumour cell arrival,4 which has led to the emergence of the concept of the premetastatic niche. We have corroborated the findings of Shinagawa et al. with a second type of human colon cancer cell line (LS174) in another original murine model of orthotopic liver metastasis. This method of BMDC supply was even systemic, which is more interesting than coinjection because the BMDCs localize preferentially and not around the tumour by necessity. Our choice of BMDCs was innovative due to the absence of sorting of the different cells that constitute the injected solution; this solution was at least a third bone marrow-derived endothelial and haematopoietic precursors cells. For the first time, we have proposed a functional role for bone marrow-derived endothelial and haematopoietic precursors cells in tumour angiogenesis and metastasis enhancement in an orthotopic nude mice model. Controlling the effects of BMDCs and understanding the molecular pathways of interaction between tumour cells and BMDCs or MSCs could be a new targeted therapy for liver colon metastasis. Yours sincerely, Raphaelle Audollent*, Clarisse Eveno* , Jean-Olivier Contreres*, Patricia Hainaud*, Aurore Rampanou*, Evelyne Dupuy* , Jean-Philippe Brouland* §, Marc Pocard* , * Unité Inserm U965, équipe “Angiogenèse et Recherche Translationnelle,” hôpital Lariboisière, Institut des Vaisseaux et du Sang, 8, rue Guy-Patin, 75475 Paris cedex 10, France, Département médico-chirurgical de pathologie digestive, Hôpital Lariboisière, 2, rue Ambroise-Paré, 75475 Paris cedex 10, France, Université Paris-Diderot, Paris-7, France, § Département d'Anatomopathologie, Hôpital Lariboisière, 2, rue Ambroise-Paré, 75475 Paris cedex 10, France.

Minireview: The Stem Cell Next Door: Skeletal and Hematopoietic Stem Cell “Niches” in Bone

Long known to be home to hematopoietic stem cells (HSC), the bone/bone marrow organ and its cellular components are directly implicated in regulating hematopoiesis and HSC function. Over the past few years, advances on the identity of HSC "niche" cells have brought into focus the role of cells of osteogenic lineage and of marrow microvessels. At the same time, the identity of self-renewing multipotent skeletal progenitors (skeletal stem cells, also known as mesenchymal stem cells) has also been more precisely defined, along with the recognition of their own microvascular niche. The two sets of evidence converge in delineating a picture in which two kinds of stem cells share an identical microanatomical location in the bone/bone marrow organ. This opens a new view on the manner in which the skeleton and hematopoiesis can cross-regulate via interacting stem cells but also a novel view of our general concept of stem cell niches.

Niche as a Determinant of Word Fate in Online Groups

Patterns of word use both reflect and influence a myriad of human activities and interactions. Like other entities that are reproduced and evolve, words rise or decline depending upon a complex interplay between their intrinsic properties and the environments in which they function. Using Internet discussion communities as model systems, we define the concept of a word niche as the relationship between the word and the characteristic features of the environments in which it is used. We develop a method to quantify two important aspects of the size of the word niche: the range of individuals using the word and the range of topics it is used to discuss. Controlling for word frequency, we show that these aspects of the word niche are strong determinants of changes in word frequency. Previous studies have already indicated that word frequency itself is a correlate of word success at historical time scales. Our analysis of changes in word frequencies over time reveals that the relative sizes of word niches are far more important than word frequencies in the dynamics of the entire vocabulary at shorter time scales, as the language adapts to new concepts and social groupings. We also distinguish endogenous versus exogenous factors as additional contributors to the fates of words, and demonstrate the force of this distinction in the rise of novel words. Our results indicate that short-term nonstationarity in word statistics is strongly driven by individual proclivities, including inclinations to provide novel information and to project a distinctive social identity.

Regional Characteristics of Niche and Planning Principles in City Streets

This paper introduces niche concept and niche overlap theory into the field of urban planning, and believe that urban niche is the extension of species niche concept. Urban provides certain resource for human beings to live and take actives, which makes different dimensions of resource, time and space in different urban's development. Regional characteristics of citiy as the manifestation of a city, which reflect different "space" position of a city in urban niche, the spatial position is multidimensional and with multiple subsystems. Regional characteristics of city mainly come from non-overlapped area of multiple subsystems in urban complex niche, the higher the proportion of non-overlapping, the more obvious features of urban regional characteristics. Therefore, this paper established a regional characteristic model of niche in city streets which based on complex ecosystem, and proposed planning principles under it, in order to emphasize regionality and create a positive ecological street.

Forecasting species ranges by statistical estimation of ecological niches and spatial population dynamics

ABSTRACTAim The study and prediction of species–environment relationships is currently mainly based on species distribution models. These purely correlative models neglect spatial population dynamics and assume that species distributions are in equilibrium with their environment. This causes biased estimates of species niches and handicaps forecasts of range dynamics under environmental change. Here we aim to develop an approach that statistically estimates process‐based models of range dynamics from data on species distributions and permits a more comprehensive quantification of forecast uncertainties.Innovation We present an approach for the statistical estimation of process‐based dynamic range models (DRMs) that integrate Hutchinson's niche concept with spatial population dynamics. In a hierarchical Bayesian framework the environmental response of demographic rates, local population dynamics and dispersal are estimated conditional upon each other while accounting for various sources of uncertainty. The method thus: (1) jointly infers species niches and spatiotemporal population dynamics from occurrence and abundance data, and (2) provides fully probabilistic forecasts of future range dynamics under environmental change. In a simulation study, we investigate the performance of DRMs for a variety of scenarios that differ in both ecological dynamics and the data used for model estimation.Main conclusions Our results demonstrate the importance of considering dynamic aspects in the collection and analysis of biodiversity data. In combination with informative data, the presented framework has the potential to markedly improve the quantification of ecological niches, the process‐based understanding of range dynamics and the forecasting of species responses to environmental change. It thereby strengthens links between biogeography, population biology and theoretical and applied ecology.

A framework for estimating niche metrics using the resemblance between qualitative resources

Despite the central importance of the niche concept for the ecological theory, current methods to quantify the species niche from qualitative resources, such as food or habitat types, remain insufficiently developed. Classically, information theory and diversity measures have formed the toolbox used for calculating resource niche metrics on species preference data for a set of qualitative resources. We provide a comprehensive framework that extends these classical approaches by incorporating the resemblance between resources into the calculation of resource niche metrics. This does not only allow estimation of the niche centre, breadth, overlap and displacement with greater accuracy, but also makes the estimates less influenced by the way the resources are subdivided. In addition, all niche metrics can be calculated while taking into account the variation in resource availability, and confidence intervals can be obtained by bootstrapping. We illustrate the utility of the framework with an analysis of dietary preferences in feral pigeons Columba livia.

Perspectives on adult neurogenesis

New neurons are generated throughout life. This discovery has challenged firmly held concepts about the structural plasticity and regenerative capacity of the mammalian brain. In this special issue of the EJN, leaders in the field summarize and review recent advances aiming to understand the molecular mechanisms underlying adult neurogenesis and the impact of new neurons on brain function in health and disease. Below we discuss pivotal yet unsolved aspects of adult neurogenesis as well as potential future directions in the field.

Isotopic niches of fishes in coastal, neritic and oceanic waters off Adélie land, Antarctica

We used the stable isotope method to investigate the ecological niches of Antarctic fishes, with δ 13C and δ 15N as proxies of fish habitats and dietary habits, respectively. Muscle isotopic signature was measured for each of 237 delipidated tissue samples from 27 fish species collected offshore Adélie Land, East Antarctica. Overall, δ 13C values ranged from −25.3‰ to −18.2‰, thus allowing characterizing of the fish habitats, with inshore/benthic species having more positive δ 13C signatures than offshore/pelagic ones. No clear difference in the δ 13C values of pelagic fishes was found between species living in neritic and oceanic waters. Overall, the δ 15N signatures of neritic pelagic and epibenthic fishes encompassed ∼1.0 trophic level (3.1‰), a higher difference than that (1.4‰) found within the oceanic assemblage. Fishes with the lowest and highest δ 15N values are primarily invertebrate- and fish-eaters, respectively. The isotopic niches of fishes illustrate the different mechanisms allowing coexistence, with most fishes segregating at least by one of the two niche axes (δ 13C and δ 15N). Muscle isotopic values also document interindividual foraging specialization over the long-term in coastal benthic fishes, but not in more offshore pelagic species. Finally, the δ 15N signatures of fishes overlap with those of penguins and seals, indicating that seabirds and marine mammals share the upper levels of the Antarctic pelagic ecosystem with some large fish species. In conclusion, the concept of isotopic niche is a powerful tool to investigate various aspects of the ecological niche of Antarctic fishes, thus complementing the use of other conventional and non-conventional approaches.

Expanding the ecological niche approach: Relationships between variability in niche position and species richness

The concept of ecological niche has remained as one of the core ideas in ecological research for almost a century. Various metrics describing niche overlap, breadth, and position have been developed during the last decades, and these have played a central role in our understanding of community organisation. However, owing to some obvious limitations in these metrics, there is a need for further development of the niche concept to provide new insights into the relationships between species richness (SR), community organisation, and underlying processes. We introduce a new metric, variability in niche positions (VNP) within local communities, describing the extent to which species positions vary in environmentally determined niche space. VNP is measured as the standard deviation of species scores along a multivariate ordination axis calculated over all species in a local community. Regardless of its simplicity, the VNP metric describes novel features in niche differentiation and species locations in environmental niche space. Therefore, it complements other measures, such as niche complementarity and overlap. Based on a few premises about species interactions and body size, we hypothesised that VNP has predictable relationships with SR. The relationships were supported by empirical data on aquatic organisms. Of the studied organism groups, lake fishes showed the strongest VNP-SR relationships, followed by lake molluscs and pond phytoplankton. Stream bryophytes and stream macroinvertebrates also showed significant, yet weak, VNP-SR relationships, but there were no significant relationships in pond zooplankton and stream diatoms. The strength of the VNP-SR relationship showed a positive correlation with the body mass of organisms. Our findings suggest that VNP increases with increasing SR in large-sized organisms. In small-sized organisms, high rates of dispersal may mask a significant relationship between VNP and SR. By contrast, in large-sized organisms, lower rates of dispersal, interspecific interactions, habitat filters, and niches are more important for community organisation. We thus find the new concept as a promising way to aid in linking species richness and niches, but we stress the VNP-SR relationships call for further testing in other communities to see its merits for community ecology.

Biodiversity and Climate Change: Integrating Evolutionary and Ecological Responses of Species and Communities

Today's scientists are facing the enormous challenge of predicting how climate change will affect species distributions and species assemblages. To do so, ecologists are widely using phenomenological models of species distributions that mainly rely on the concept of species niche and generally ignore species' demography, species' adaptive potential, and biotic interactions. This review examines the potential role of the emerging synthetic discipline of evolutionary community ecology in improving our understanding of how climate change will alter future distribution of biodiversity. We review theoretical and empirical advances about the role of niche evolution, interspecific interactions, and their interplay in altering species geographic ranges and community assembly. We discuss potential ways to integrate complex feedbacks between ecology and evolution in ecological forecasting. We also point at a number of caveats in our understanding of the eco-evolutionary consequences of climate change and highlight several challenges for future research.

History and heroes: the thermal niche of fishes and long‐term lake ice dynamics*

These perspectives on climate change come largely from two views, i.e. that of a fish and fisheries ecologist with an autecological interest and that of a limnologist interested in long-term dynamics and change. Ideas about the thermal niche evolved from the late F. E. J. Fry's (University of Toronto) paradigm of fish response to environmental factors and the late G. Evelyn Hutchinson's (Yale University) formalization of the niche concept. In contrast, ideas about climatic change and variability have been shaped by long-term observation records from lakes around the northern hemisphere. The history of each set of ideas, i.e. the thermal niche of fishes and learning from nature's long-term dynamics, is briefly reviewed in the context of climatic change.

The Regulation of Differentiation in Mesenchymal Stem Cells

Mesenchymal stromal/stem cells (MSCs) are a population of stromal cells present in the bone marrow and most connective tissues, capable of differentiation into mesenchymal tissues such as bone and cartilage. MSCs are attractive candidates for biological cell-based tissue repair approaches because of their extensive proliferative ability in culture while retaining their mesenchymal multilineage differentiation potential. In addition to its undoubted scientific interest, the prospect of monitoring and controlling MSC differentiation is a crucial regulatory and clinical requirement. Hence, the molecular regulation of MSC differentiation has been extensively studied. Most of the studies are in vitro, because the identity of MSCs in their tissues of origin in vivo remains undefined. This review addresses the current knowledge of the molecular basis of differentiation of cultured MSCs, with a particular focus on chondrogenesis and osteogenesis. Building on the information coming from developmental biology studies of embryonic skeletogenesis, several signaling pathways and transcription factors have been investigated and shown to play critical roles in MSC differentiation. In particular, the Wnt and transforming growth factor-β/bone morphogenetic protein signaling pathways are well known to modulate in MSCs the molecular differentiation into cartilage and bone. Relevant to the emerging concept of stem cell niches is the demonstration that physical factors can also participate in the regulation of MSC differentiation. Knowledge of the regulation of MSC differentiation will be critical in the design of three-dimensional culture systems and bioreactors for automated bioprocessing through mathematical models applied to systems biology and network science.