Metacommunity

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An ecological metacommunity is a set of interacting communities which are linked by the dispersal of multiple, potentially interacting species. [1] [2] [3] The term is derived from the field of community ecology, which is primarily concerned with patterns of species distribution, abundance and interactions. Metacommunity ecology combines the importance of local factors (environmental conditions, competition, predation) and regional factors (dispersal of individuals, immigration, emigration) to explain patterns of species distributions that happen in different spatial scales.

There are four theoretical frameworks, or unifying themes, that each detail specific mechanistic processes useful for predicting empirical community patterns. These are the patch dynamics, species sorting, source–sink dynamics (or mass effect) and neutral model frameworks. Patch dynamics models describe species composition among multiple, identical patches, such as islands. In this framework, species are able to persist on patches through tradeoffs in colonization ability and competitive ability, where less competitive species can disperse to unoccupied patches faster than they go extinct in others. [4] Species sorting models describe variation in abundance and composition within the metacommunity due to individual species responses to environmental heterogeneity, such that certain local conditions may favor certain species and not others. Under this perspective, species are able to persist in patches with suitable environmental conditions resulting in a strong correlation between local species composition and the environment. This model represents the classical theories of the niche-centric era of G. Evelyn Hutchinson and Robert MacArthur. Source-sink models describe a framework in which dispersal and environmental heterogeneity interact to determine local and regional abundance and composition. This framework is derived from the metapopulation ecology term describing source–sink dynamics at the population level. High levels of dispersal among habitat patches allow populations to be maintained in environments that are normally outside the species environmental range. Finally, the neutral perspective describes a framework where species are essentially equivalent in their competitive and dispersal abilities, and local and regional composition and abundance are determined primarily by stochastic demographic processes and dispersal limitation. [5] The neutral perspective was recently popularized by Stephen P. Hubbell following his groundbreaking work on the unified neutral theory of biodiversity.

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<span class="mw-page-title-main">Theoretical ecology</span>

Theoretical ecology is the scientific discipline devoted to the study of ecological systems using theoretical methods such as simple conceptual models, mathematical models, computational simulations, and advanced data analysis. Effective models improve understanding of the natural world by revealing how the dynamics of species populations are often based on fundamental biological conditions and processes. Further, the field aims to unify a diverse range of empirical observations by assuming that common, mechanistic processes generate observable phenomena across species and ecological environments. Based on biologically realistic assumptions, theoretical ecologists are able to uncover novel, non-intuitive insights about natural processes. Theoretical results are often verified by empirical and observational studies, revealing the power of theoretical methods in both predicting and understanding the noisy, diverse biological world.

<span class="mw-page-title-main">Landscape ecology</span> Science of relationships between ecological processes in the environment and particular ecosystems

Landscape ecology is the science of studying and improving relationships between ecological processes in the environment and particular ecosystems. This is done within a variety of landscape scales, development spatial patterns, and organizational levels of research and policy. Concisely, landscape ecology can be described as the science of "landscape diversity" as the synergetic result of biodiversity and geodiversity.

<span class="mw-page-title-main">Unified neutral theory of biodiversity</span> Theory of evolutionary biology

The unified neutral theory of biodiversity and biogeography is a theory and the title of a monograph by ecologist Stephen P. Hubbell. It aims to explain the diversity and relative abundance of species in ecological communities. Like other neutral theories of ecology, Hubbell assumes that the differences between members of an ecological community of trophically similar species are "neutral", or irrelevant to their success. This implies that niche differences do not influence abundance and the abundance of each species follows a random walk. The theory has sparked controversy, and some authors consider it a more complex version of other null models that fit the data better.

<span class="mw-page-title-main">Population ecology</span> Study of the dynamics of species populations and how these populations interact with the environment

Population ecology is a sub-field of ecology that deals with the dynamics of species populations and how these populations interact with the environment, such as birth and death rates, and by immigration and emigration.

<span class="mw-page-title-main">Metapopulation</span> Group of separated yet interacting ecological populations

A metapopulation consists of a group of spatially separated populations of the same species which interact at some level. The term metapopulation was coined by Richard Levins in 1969 to describe a model of population dynamics of insect pests in agricultural fields, but the idea has been most broadly applied to species in naturally or artificially fragmented habitats. In Levins' own words, it consists of "a population of populations".

<span class="mw-page-title-main">Community (ecology)</span> Associated populations of species in a given area

In ecology, a community is a group or association of populations of two or more different species occupying the same geographical area at the same time, also known as a biocoenosis, biotic community, biological community, ecological community, or life assemblage. The term community has a variety of uses. In its simplest form it refers to groups of organisms in a specific place or time, for example, "the fish community of Lake Ontario before industrialization".

Source–sink dynamics is a theoretical model used by ecologists to describe how variation in habitat quality may affect the population growth or decline of organisms.

<span class="mw-page-title-main">Cross-boundary subsidy</span>

Cross-boundary subsidies are caused by organisms or materials that cross or traverse habitat patch boundaries, subsidizing the resident populations. The transferred organisms and materials may provide additional predators, prey, or nutrients to resident species, which can affect community and food web structure. Cross-boundary subsidies of materials and organisms occur in landscapes composed of different habitat patch types, and so depend on characteristics of those patches and on the boundaries in between them. Human alteration of the landscape, primarily through fragmentation, has the potential to alter important cross-boundary subsidies to increasingly isolated habitat patches. Understanding how processes that occur outside of habitat patches can affect populations within them may be important to habitat management.

<span class="mw-page-title-main">Paradox of the plankton</span> The ecological observation of high plankton diversity despite competition for few resources

In aquatic biology, the paradox of the plankton describes the situation in which a limited range of resources supports an unexpectedly wide range of plankton species, apparently flouting the competitive exclusion principle, which holds that when two species compete for the same resource, one will be driven to extinction.

Ecological extinction is "the reduction of a species to such low abundance that, although it is still present in the community, it no longer interacts significantly with other species".

Patch dynamics is an ecological perspective that the structure, function, and dynamics of ecological systems can be understood through studying their interactive patches. Patch dynamics, as a term, may also refer to the spatiotemporal changes within and among patches that make up a landscape. Patch dynamics is ubiquitous in terrestrial and aquatic systems across organizational levels and spatial scales. From a patch dynamics perspective, populations, communities, ecosystems, and landscapes may all be studied effectively as mosaics of patches that differ in size, shape, composition, history, and boundary characteristics.

In ecology, the occupancy–abundance (O–A) relationship is the relationship between the abundance of species and the size of their ranges within a region. This relationship is perhaps one of the most well-documented relationships in macroecology, and applies both intra- and interspecifically. In most cases, the O–A relationship is a positive relationship. Although an O–A relationship would be expected, given that a species colonizing a region must pass through the origin and could reach some theoretical maximum abundance and distribution, the relationship described here is somewhat more substantial, in that observed changes in range are associated with greater-than-proportional changes in abundance. Although this relationship appears to be pervasive, and has important implications for the conservation of endangered species, the mechanism(s) underlying it remain poorly understood

Ecological traps are scenarios in which rapid environmental change leads organisms to prefer to settle in poor-quality habitats. The concept stems from the idea that organisms that are actively selecting habitat must rely on environmental cues to help them identify high-quality habitat. If either the habitat quality or the cue changes so that one does not reliably indicate the other, organisms may be lured into poor-quality habitat.

Relative species abundance is a component of biodiversity and is a measure of how common or rare a species is relative to other species in a defined location or community. Relative abundance is the percent composition of an organism of a particular kind relative to the total number of organisms in the area. Relative species abundances tend to conform to specific patterns that are among the best-known and most-studied patterns in macroecology. Different populations in a community exist in relative proportions; this idea is known as relative abundance.

In macroecology and community ecology, an occupancy frequency distribution (OFD) is the distribution of the numbers of species occupying different numbers of areas. It was first reported in 1918 by the Danish botanist Christen C. Raunkiær in his study on plant communities. The OFD is also known as the species-range size distribution in literature.

In ecology, extinction debt is the future extinction of species due to events in the past. The phrases dead clade walking and survival without recovery express the same idea.

Species sorting is a mechanism in the metacommunity framework of ecology whereby species distributions and abundances can be related to the environmental or biotic conditions in a particular habitat. The species sorting paradigm describes a system of habitat patches with different environmental conditions that organisms can move between. Species are able to disperse to patches with suitable environmental conditions, resulting in patterns where environmental conditions can predict the species found in a particular habitat.

<span class="mw-page-title-main">Mark C. Urban</span> American biologist

Mark C. Urban is a biologist and associate professor in ecology and evolutionary biology at the University of Connecticut. His work focuses on the ecological and evolutionary mechanisms that shape natural communities across multiple spatial scales.

The rescue effect is a phenomenon which was first described by Brown and Kodric-Brown, and is commonly used in metapopulation dynamics and many other disciplines in ecology. This populational process explains how the migration of individuals can increase the persistence of small isolated populations by helping to stabilize a metapopulation, thus reducing the chances of extinction. In other words, immigration can lead to the recolonization of previously extinct patches, promoting the long-term persistence of the network of populations.

Priyanga Amarasekare is a Professor of Ecology and Evolutionary Biology at the University of California, Los Angeles (UCLA) and distinguished Fellow of the Ecological Society of America (ESA). Her research is in the fields of mathematical biology and trophic ecology, with a focus on understanding patterns of biodiversity, species dispersal and the impacts of climate change. She received a 2021 Guggenheim Fellowship and received ESA's Robert H. MacArthur Award in 2022.

References

  1. Gilpin, M.E. and I.A. Hanski (1991). Metapopulation dynamics: Empirical and Theoretical Investigations. Academic Press, London.
  2. Wilson, D.S. (1992). Complex interactions in metacommunities, with implications for biodiversity and higher levels of selection. Ecology, 73: 1984-2000.
  3. Leibold, M.A., M. Holyoak, N. Mouquet and others (2004). The metacommunity concept: a framework for multi-scale community ecology. Ecology Letters,7: 601-613.
  4. Holyoak (2005). Metacommunities: Spatial dynamics and ecological communities. University of Chicago Press. ISBN   9780226350646.
  5. Hubbell, Stephen P. (2001). The Unified Neutral Theory of Biodiversity and Biogeography (MPB-32). Princeton University Press. ISBN   9781400837526. OCLC   956448724.