Mechanisms of Maintenance of Species Diversity

Annual Review of Ecology and Systematics, Journal Year: 2000, Volume and Issue: 31(1), P. 343 - 366

Published: Nov. 1, 2000

▪ Abstract The focus of most ideas on diversity maintenance is species coexistence, which may be stable or unstable. Stable coexistence can quantified by the long-term rates at community members recover from low density. Quantification shows that mechanisms function in two major ways: They (a) equalizing because they tend to minimize average fitness differences between species, (b) stabilizing increase negative intraspecific interactions relative interspecific interactions. Stabilizing are essential for and include traditional such as resource partitioning frequency-dependent predation, well depend fluctuations population densities environmental factors space time. Equalizing contribute reduce large inequalities might negate effects mechanisms. Models unstable coexitence, slowly decays over time, have focused almost exclusively These models would more robust if also included mechanisms, arise many varied ways but need not adequate full stability a system. invite broader view incorporating turnover.

Language: Английский

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The Dilemma of Plants: To Grow or Defend

The Quarterly Review of Biology, Journal Year: 1992, Volume and Issue: 67(3), P. 283 - 335

Published: Sept. 1, 1992

Physiological and ecological constraints play key roles in the evolution of plant growth patterns, especially relation to defenses against herbivores. Phenotypic life history theories are unified within growth-differentiation balance (GDB) framework, forming an integrated system explaining predicting patterns defense competitive interactions evolutionary time. Plant activity at cellular level can be classified as (cell division enlargement) differentiation (chemical morphological changes leading cell maturation specialization). The GDB hypothesis is premised upon a physiological trade-off between processes. exists because secondary metabolism structural reinforcement physiologically constrained dividing enlarging cells, they divert resources from production new leaf area. Hence dilemma plants: They must grow fast enough complete, yet maintain necessary survive presence pathogens hervivores. processes interacts with herbivory plant-plant competition manifest itself genetic strategies. Evolutionary reviewed. We also extend standard rate model by separating its components,and formalizing role defense. conclude conceptual which physioligical trade-offs interact abiotic environment, herbivory.

Language: Английский

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Scaling environmental change through the community‐level: a trait‐based response‐and‐effect framework for plants

Global Change Biology, Journal Year: 2008, Volume and Issue: 14(5), P. 1125 - 1140

Published: Jan. 31, 2008

Abstract Predicting ecosystem responses to global change is a major challenge in ecology. A critical step that understand how changing environmental conditions influence processes across levels of ecological organization. While direct scaling from individual dynamics can lead robust and mechanistic predictions, new approaches are needed appropriately translate questions through the community level. Species invasion, loss, turnover all necessitate this processes, but predicting such changes may function notoriously difficult. We suggest community‐level be incorporated into predictions using trait‐based response–effect framework differentiates response (predicted by traits) effect on traits). develop response‐and‐effect functional framework, concentrating relationships among species' response, effect, abundance general concerning magnitude direction function. then detail several key research directions better scale effects These include (1) trait characterization, (2) linkages between traits, (3) importance species interactions expression, (4) incorporation feedbacks multiple temporal scales. Increasing rates extinction invasion modifying communities worldwide make agenda imperative.

Language: Английский

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Plant Competition Underground

Annual Review of Ecology and Systematics, Journal Year: 1997, Volume and Issue: 28(1), P. 545 - 570

Published: Nov. 1, 1997

Belowground competition occurs when plants decrease the growth, survival, or fecundity of neighbors by reducing available soil resources. Competition belowground can be stronger and involve many more than aboveground competition. Physiological ecologists population community have traditionally studied from different perspectives. Physiologically based studies often measure resource uptake without determining integrated consequences for plant performance, while level examine performance but fail to identify intermediary mechanism. competitive ability is correlated with such attributes as root density, surface area, plasticity either in growth properties enzymes involved nutrient uptake. Unlike light, which larger a disproportionate advantage shading smaller ones, resources apparently symmetric. decreases increases levels, it premature generalize about relative importance above- across gradients. Although shoot are assumed additive effects on some provide evidence contrary, potential interactions between two forms should considered future investigations. Other research recommendations include simultaneous study gaps, since their closures may not occur simultaneously, improved estimates neighborhood. Only combining tools perspectives physiological ecology biology we fully understand how characteristics, neighborhood structure, global climate change influence influenced belowground.

Language: Английский

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THE INTERPLAY OF FACILITATION AND COMPETITION IN PLANT COMMUNITIES

Ecology, Journal Year: 1997, Volume and Issue: 78(7), P. 1966 - 1975

Published: Oct. 1, 1997

If plants cannot simultaneously acclimate to shade and drought because of physiological trade-offs, then are expected be less tolerant shading under drier conditions. One observation that, at first sight, seems incompatible with this idea is the fact that establishment new in dry areas often restricted shady sites canopy other plants, called "nurse plants." We use a graphical model resolve paradox. The visualizes how facilitative patterns can understood from simultaneous effects plant canopies on microsite light moisture, growth responses establishing seedlings those factors. approach emphasizes positive negative always occur simultaneously. In presented light–water model, facilitation only occurs when improvement water relations exceeds costs caused by lower levels. This may true conditions, whereas situations, competition rather than observed. shows changes availability shift interactions competitive vice versa, as observed some field patterns. It argued environmental factors explaining same context.

Language: Английский

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The Roles of Harsh and Fluctuating Conditions in the Dynamics of Ecological Communities

The American Naturalist, Journal Year: 1997, Volume and Issue: 150(5), P. 519 - 553

Published: Nov. 1, 1997

Harsh conditions (e.g., mortality and stress) reduce population growth rates directly; secondarily, they may the intensity of interactions between organisms. Near-exclusive focus on secondary effect these forms harshness has led ecologists to believe that importance ecological interactions, such as competition, favor coexistence even ecologically very similar species. By examining both costs benefits, we show alone does not lessen species or limit their role in community structure. Species requires niche differences, itself make more likely. Fluctuations environmental disturbance, seasonal change, weather variation) also have been regarded decreasing favoring coexistence, but argue can only be favored when fluctuations create spatial temporal opportunities. We important diversity-promoting roles for harsh fluctuating depend deviations from assumptions additive effects linear dependencies most commonly found models. Such considerations imply strong diversity a community.

Language: Английский

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A Meta-Analysis of Competition in Field Experiments

The American Naturalist, Journal Year: 1992, Volume and Issue: 140(4), P. 539 - 572

Published: Oct. 1, 1992

A meta-analysis was conducted on field-competition experiments published in six journals over a 10-yr period. We analyzed the effects of competition biomass organisms belonging to 93 species wide variety habitats. Competition had large effect overall, with great deal heterogeneity that among organisms. There were differences trophic levels competitive effects, but relative magnitude at different contrary predictions ecological theory. Primary producers and carnivores displayed small medium effects. In these two groups, interspecific did not differ from intraspecific nor terrestrial versus aquatic The herbivores ranged anurans lotic arthropods, marine mollusks echinoderms, statistically distinguishable zero for arthropods. Interspecific herbivore groups generally less than Among primary producers, high- low-productivity Across all taxa, experience greater organisms, depend size attained absence competitors. weakly density-dependent cases which it possible examine density neighbors. Experiments caged resulted those free-roaming unenclosed sample sizes, short durations, poor experimental design more variable larger, longer, better planned.

Language: Английский

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Patterns and Consequences of Interspecific Competition in Natural Communities: A Review of Field Experiments with Plants

The American Naturalist, Journal Year: 1992, Volume and Issue: 139(4), P. 771 - 801

Published: April 1, 1992

We present a quantitative literature review to assess the extent which field experiments with plants have addressed questions about patterns of competition over time and space, consequences for community structure, comparisons competitive ability among species. outline necessary treatment statistical analyses answer each question then describe number that meet these criteria their results. Although we found total 101 in 89 studies, 63% only whether significantly affected some component individual fitness single species at site. Despite limited data base address more complex interactions, did find consistent results few reviewed. Where tested, always had significant effects on distribution (five experiments), relative abundances (two diversity (four notion has strong structure. On other hand, intraspecific was not usually stronger than interspecific either effect experiments) or response (three suggests resource partitioning may be an important mechanism coexistence plants.

Language: Английский

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PHENOTYPIC PLASTICITY AND INTERACTIONS AMONG PLANTS

Ecology, Journal Year: 2003, Volume and Issue: 84(5), P. 1115 - 1128

Published: May 1, 2003

We know a great deal about the plastic responses of plant phenotypes to abiotic and biotic environment, but very little consequences phenotypic plasticity for communities. In other words, we that traits can vary widely given genotype, importance trait-mediated interactions (TMI) among plants. Here, discuss three major factors affect expression plasticity: variation in presence or identity neighbors, herbivory. consider how these might Plastic environment have important conditionality competitive effects, point causing shifts from facilitative interactions. Because plants show high degree response even specific identify may allow species adjust composition their communities, promoting coexistence community diversity. Likewise, consumers various counterintuitive consequences: induction resistance, compensatory growth, increased resource uptake ways cannot be predicted simply by considering biomass lost consumers. What TMI suggests they should not ignored theory. Although work date on has been hampered experimental constraints, new approaches such as manipulating using signals instead actual environmental conditions use transgenic us rapidly expand our understanding plasticity. Corresponding Editor: F. R. Adler. For reprints this Special Feature, see footnote 1, p. 1081.

Language: Английский

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COEXISTENCE OF THE NICHE AND NEUTRAL PERSPECTIVES IN COMMUNITY ECOLOGY

Ecology, Journal Year: 2006, Volume and Issue: 87(6), P. 1399 - 1410

Published: June 1, 2006

The neutral theory for community structure and biodiversity is dependent on the assumption that species are equivalent to each other in all important ecological respects. We explore what this concept of equivalence means communities, how such may arise evolutionarily, possibility equivalents relates previous ideas about niche differentiation. also show co-occurrence ecologically similar or not incompatible with as has been supposed, because relations can sometimes favor coexistence species. argue both evolutionary processes operate promote introduction sustain persistence many cases nearly embedded highly structured food webs. Future work should focus synthesizing perspectives rather than dichotomously debating whether models provide better explanations biodiversity.

Language: Английский

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