1
|
Downie J, Taylor AFS, Iason G, Moore B, Silvertown J, Cavers S, Ennos R. Location, but not defensive genotype, determines ectomycorrhizal community composition in Scots pine ( Pinus sylvestris L.) seedlings. Ecol Evol 2021; 11:4826-4842. [PMID: 33976851 PMCID: PMC8093658 DOI: 10.1002/ece3.7384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 02/01/2021] [Accepted: 02/12/2021] [Indexed: 11/28/2022] Open
Abstract
For successful colonization of host roots, ectomycorrhizal (EM) fungi must overcome host defense systems, and defensive phenotypes have previously been shown to affect the community composition of EM fungi associated with hosts. Secondary metabolites, such as terpenes, form a core part of these defense systems, but it is not yet understood whether variation in these constitutive defenses can result in variation in the colonization of hosts by specific fungal species.We planted seedlings from twelve maternal families of Scots pine (Pinus sylvestris) of known terpene genotype reciprocally in the field in each of six sites. After 3 months, we characterized the mycorrhizal fungal community of each seedling using a combination of morphological categorization and molecular barcoding, and assessed the terpene chemodiversity for a subset of the seedlings. We examined whether parental genotype or terpene chemodiversity affected the diversity or composition of a seedling's mycorrhizal community.While we found that terpene chemodiversity was highly heritable, we found no evidence that parental defensive genotype or a seedling's terpene chemodiversity affected associations with EM fungi. Instead, we found that the location of seedlings, both within and among sites, was the only determinant of the diversity and makeup of EM communities.These results show that while EM community composition varies within Scotland at both large and small scales, variation in constitutive defensive compounds does not determine the EM communities of closely cohabiting pine seedlings. Patchy distributions of EM fungi at small scales may render any genetic variation in associations with different species unrealizable in field conditions. The case for selection on traits mediating associations with specific fungal species may thus be overstated, at least in seedlings.
Collapse
Affiliation(s)
- Jim Downie
- Ashworth LaboratoriesInstitute of Evolutionary BiologyUniversity of EdinburghEdinburghUK
- Centre for Ecology and HydrologyPenicuikUK
- School of Natural SciencesBangor UniversityWalesUK
| | - Andy F. S. Taylor
- The James Hutton InstituteAberdeenUK
- Institute of Biological and Environmental SciencesUniversity of AberdeenAberdeenUK
| | | | - Ben Moore
- The James Hutton InstituteAberdeenUK
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNSWAustralia
| | - Jonathan Silvertown
- Ashworth LaboratoriesInstitute of Evolutionary BiologyUniversity of EdinburghEdinburghUK
| | | | - Richard Ennos
- Ashworth LaboratoriesInstitute of Evolutionary BiologyUniversity of EdinburghEdinburghUK
| |
Collapse
|
2
|
Downie J, Silvertown J, Cavers S, Ennos R. Heritable genetic variation but no local adaptation in a pine-ectomycorrhizal interaction. Mycorrhiza 2020; 30:185-195. [PMID: 32078050 PMCID: PMC7228896 DOI: 10.1007/s00572-020-00941-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 02/12/2020] [Indexed: 06/08/2023]
Abstract
Local adaptation of plants to mycorrhizal fungi helps determine the outcome of mycorrhizal interactions. However, there is comparatively little work exploring the potential for evolution in interactions with ectomycorrhizal fungi, and fewer studies have explored the heritability of mycorrhizal responsiveness, which is required for local adaptation to occur. We set up a reciprocal inoculation experiment using seedlings and soil from four populations of Scots pine (Pinus sylvestris) from Scotland, measuring seedling response to mycorrhizal inoculation after 4 months. We estimated heritability for the response traits and tested for genotype × environment interactions. While we found that ectomycorrhizal responsiveness was highly heritable, we found no evidence that pine populations were locally adapted to fungal communities. Instead, we found a complex suite of interactions between pine population and soil inoculum. Our results suggest that, while Scots pine has the potential to evolve in response to mycorrhizal fungi, evolution in Scotland has not resulted in local adaptation. Long generation times and potential for rapid shifts in fungal communities in response to environmental change may preclude the opportunity for such adaptation in this species, and selection for other factors such as resistance to fungal pathogens may explain the pattern of interactions found.
Collapse
Affiliation(s)
- Jim Downie
- Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, Scotland.
- Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian, Scotland.
| | - Jonathan Silvertown
- Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, Scotland
| | - Stephen Cavers
- Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian, Scotland
| | - Richard Ennos
- Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, Scotland
| |
Collapse
|
3
|
Moorad J, Promislow D, Silvertown J. George C. Williams' Problematic Model of Selection and Senescence: Time to Move on. Trends Ecol Evol 2020; 35:303-305. [PMID: 32187508 DOI: 10.1016/j.tree.2020.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 01/31/2020] [Accepted: 02/03/2020] [Indexed: 02/07/2023]
Affiliation(s)
- Jacob Moorad
- Institute of Evolutionary Biology, University of Edinburgh, Charlotte Auerbach Rd., Edinburgh EH9 3FL, UK
| | - Daniel Promislow
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Jonathan Silvertown
- Institute of Evolutionary Biology, University of Edinburgh, Charlotte Auerbach Rd., Edinburgh EH9 3FL, UK.
| |
Collapse
|
4
|
Moorad J, Promislow D, Silvertown J. Evolutionary Ecology of Senescence and a Reassessment of Williams' 'Extrinsic Mortality' Hypothesis. Trends Ecol Evol 2019; 34:519-530. [PMID: 30857756 DOI: 10.1016/j.tree.2019.02.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 02/08/2019] [Accepted: 02/12/2019] [Indexed: 10/27/2022]
Abstract
The evolutionary theory of senescence underpins research in life history evolution and the biology of aging. In 1957 G.C. Williams predicted that higher adult death rates select for earlier senescence and shorter length of life, but preadult mortality does not matter to the evolution of senescence. This was subsequently interpreted as predicting that senescence should be caused by 'extrinsic' sources of mortality. This idea still motivates empirical studies, although formal, mathematical theory shows it is wrong. It has nonetheless prospered because it offers an intuitive explanation for patterns observed in nature. We review the flaws in Williams' model, explore alternative explanations for comparative patterns that are consistent with the evolutionary theory of senescence, and discuss how hypotheses based on it can be tested. We argue that focusing on how sources of mortality affect ages differently offers greater insight into evolutionary processes.
Collapse
Affiliation(s)
- Jacob Moorad
- Institute of Evolutionary Biology, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Daniel Promislow
- Department of Pathology and Department of Biology, University of Washington, Seattle, WA, USA. https://twitter.com@DPromislow
| | - Jonathan Silvertown
- Institute of Evolutionary Biology, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK. https://twitter.com@JWSilvertown
| |
Collapse
|
5
|
Dodd ME, Silvertown J, Chase MW. PHYLOGENETIC ANALYSIS OF TRAIT EVOLUTION AND SPECIES DIVERSITY VARIATION AMONG ANGIOSPERM FAMILIES. Evolution 2017; 53:732-744. [DOI: 10.1111/j.1558-5646.1999.tb05367.x] [Citation(s) in RCA: 128] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/1998] [Accepted: 01/25/1999] [Indexed: 11/28/2022]
Affiliation(s)
- Michael E. Dodd
- Ecology and Conservation Research Group, Biology Department; Open University; Milton Keynes MK7 6AA United Kingdom
| | - Jonathan Silvertown
- Ecology and Conservation Research Group, Biology Department; Open University; Milton Keynes MK7 6AA United Kingdom
| | - Mark W. Chase
- Royal Botanic Gardens, Kew; Richmond Surrey TW9 3DS United Kingdom
| |
Collapse
|
6
|
Silvertown J. Ecologists Need to be Cautious about Economic Metaphors: A Reply. Trends Ecol Evol 2016; 31:336. [DOI: 10.1016/j.tree.2016.03.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 03/04/2016] [Accepted: 03/07/2016] [Indexed: 11/28/2022]
|
7
|
Pocock MJ, Evans DM, Fontaine C, Harvey M, Julliard R, McLaughlin Ó, Silvertown J, Tamaddoni-Nezhad A, White PC, Bohan DA. The Visualisation of Ecological Networks, and Their Use as a Tool for Engagement, Advocacy and Management. ADV ECOL RES 2016. [DOI: 10.1016/bs.aecr.2015.10.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
|
8
|
Silvertown J. Have Ecosystem Services Been Oversold? Trends Ecol Evol 2015; 30:641-648. [DOI: 10.1016/j.tree.2015.08.007] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 08/17/2015] [Accepted: 08/18/2015] [Indexed: 10/23/2022]
|
9
|
Silvertown J, Harvey M, Greenwood R, Dodd M, Rosewell J, Rebelo T, Ansine J, McConway K. Crowdsourcing the identification of organisms: A case-study of iSpot. Zookeys 2015:125-46. [PMID: 25685027 PMCID: PMC4319112 DOI: 10.3897/zookeys.480.8803] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 01/21/2015] [Indexed: 11/26/2022] Open
Abstract
Accurate species identification is fundamental to biodiversity science, but the natural history skills required for this are neglected in formal education at all levels. In this paper we describe how the web application ispotnature.org and its sister site ispot.org.za (collectively, “iSpot”) are helping to solve this problem by combining learning technology with crowdsourcing to connect beginners with experts. Over 94% of observations submitted to iSpot receive a determination. External checking of a sample of 3,287 iSpot records verified > 92% of them. To mid 2014, iSpot crowdsourced the identification of 30,000 taxa (>80% at species level) in > 390,000 observations with a global community numbering > 42,000 registered participants. More than half the observations on ispotnature.org were named within an hour of submission. iSpot uses a unique, 9-dimensional reputation system to motivate and reward participants and to verify determinations. Taxon-specific reputation points are earned when a participant proposes an identification that achieves agreement from other participants, weighted by the agreers’ own reputation scores for the taxon. This system is able to discriminate effectively between competing determinations when two or more are proposed for the same observation. In 57% of such cases the reputation system improved the accuracy of the determination, while in the remainder it either improved precision (e.g. by adding a species name to a genus) or revealed false precision, for example where a determination to species level was not supported by the available evidence. We propose that the success of iSpot arises from the structure of its social network that efficiently connects beginners and experts, overcoming the social as well as geographic barriers that normally separate the two.
Collapse
Affiliation(s)
- Jonathan Silvertown
- Department of Environment, Earth and Ecosystems, The Open University, Milton Keynes, MK7 6AA, UK ; Current address: Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, Scotland, UK
| | - Martin Harvey
- Department of Environment, Earth and Ecosystems, The Open University, Milton Keynes, MK7 6AA, UK
| | - Richard Greenwood
- Institute of Educational Technology, The Open University, Milton Keynes, MK7 6AA, UK
| | - Mike Dodd
- Department of Environment, Earth and Ecosystems, The Open University, Milton Keynes, MK7 6AA, UK
| | - Jon Rosewell
- Faculty of Maths, Computing and Technology, The Open University, Milton Keynes, MK7 6AA, UK
| | - Tony Rebelo
- South African National Biodiversity Institute, Kirstenbosch, Claremont, Cape Town, South Africa
| | - Janice Ansine
- Department of Environment, Earth and Ecosystems, The Open University, Milton Keynes, MK7 6AA, UK
| | - Kevin McConway
- Faculty of Maths, Computing and Technology, The Open University, Milton Keynes, MK7 6AA, UK
| |
Collapse
|
10
|
Amat ME, Silvertown J, Vargas P. Strong spatial genetic structure reduces reproductive success in the critically endangered plant genus Pseudomisopates. ACTA ACUST UNITED AC 2013; 104:692-703. [PMID: 23885091 DOI: 10.1093/jhered/est042] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Clonal growth can be a double-edged sword for endangered species, because the short-term insurance against extinction may incur a longer-term hazard of creating small inbred populations with low fecundity. In the present study, we quantify the advantages and disadvantages of clonal growth regarding the fitness of the central Iberian monotypic endangered genus Pseudomisopates. Preliminary studies showed that the species is self-incompatible and exhibits extensive clonal growth with plants flowering profusely. However, seeds at many sites seemed to be unviable, and no seedlings have been observed in the field. A fully replicated nested sampling design (n = 100) was conducted to explore genetic (using seven SSR loci) and environmental factors potentially affecting seed viability, such as: 1) clonal and genetic diversity, 2) spatial genetic structure, and 3) environmental factors (shrub cover and grazing). Generalized Linear Mixed Models were fitted relating genetic and environmental variables to reproductive variables (seed viability and flower display). Our results indicate that the relatively low genotypic diversity of the population (PD = 0.23), as quantified by SSRs, and the strong spatial genetic structure observed are congruent with intense clonal growth. This clonal growth is enhanced by unfavorable environmental conditions, such as canopy closure and grazing. Under these circumstances, both flower display and mate availability decrease, thus hindering sexual reproduction. Indeed, a mixed reproductive system (clonal and sexual) to escape environmental stochasticity is crucial for the survival of Pseudomisopates, a species inhabiting a disturbance-prone ecosystem.
Collapse
Affiliation(s)
- María E Amat
- Real Jardín Botánico de Madrid, CSIC, Plaza de Murillo 2, Madrid, Spain.
| | | | | |
Collapse
|
11
|
Abstract
BACKGROUND AND AIMS Species in plant communities segregate along fine-scale hydrological gradients. Although this phenomenon is not unique to fynbos, this community regenerates after fire and therefore provides an opportunity to study the ecological genesis of hydrological niche segregation. METHODS Following wildfires at two field sites where we had previously mapped the vegetation and monitored the hydrology, seeds were moved experimentally in >2500 intact soil cores up and down soil-moisture gradients to test the hypothesis that hydrological niche segregation is established during the seedling phase of the life cycle. Seedling numbers and growth were then monitored and they were identified using DNA bar-coding, the first use of this technology for an experiment of this kind. KEY RESULTS At the site where niche segregation among Restionaceae had previously been found, the size of seedlings was significantly greater, the wetter the location into which they were moved, regardless of the soil moisture status of their location of origin, or of the species. Seedling weight was also significantly greater in a competition treatment where the roots of other species were excluded. No such effects were detected at the control site where niche segregation among Restionaceae was previously found to be absent. CONCLUSIONS The finding that seedling growth on hydrological gradients in the field is affected by soil moisture status and by root competition shows that hydrological niche segregation could potentially originate in the seedling stage. The methodology, applied at a larger scale and followed-through for a longer period, could be used to determine whether species are differently affected by soil moisture.
Collapse
Affiliation(s)
- Jonathan Silvertown
- Department of Environment, Earth and Ecosystems, Open University, Walton Hall, Milton Keynes, UK.
| | | | | | | |
Collapse
|
12
|
Worthington JP, Silvertown J, Cook L, Cameron R, Dodd M, Greenwood RM, McConway K, Skelton P. Evolution MegaLab: a case study in citizen science methods. Methods Ecol Evol 2011. [DOI: 10.1111/j.2041-210x.2011.00164.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
13
|
Freeland JR, Biss P, Silvertown J. Contrasting patterns of pollen and seed flow influence the spatial genetic structure of sweet vernal grass (Anthoxanthum odoratum) populations. ACTA ACUST UNITED AC 2011; 103:28-35. [PMID: 22003195 DOI: 10.1093/jhered/esr111] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The spatial genetic structure of plant populations is determined by a combination of gene flow, genetic drift, and natural selection. Gene flow in most plants can result from either seed or pollen dispersal, but detailed investigations of pollen and seed flow among populations that have diverged following local adaptation are lacking. In this study, we compared pollen and seed flow among 10 populations of sweet vernal grass (Anthoxanthum odoratum) on the Park Grass Experiment. Overall, estimates of genetic differentiation that were based on chloroplast DNA (cpDNA) and, which therefore resulted primarily from seed flow, were lower (average F(ST) = 0.058) than previously published estimates that were based on nuclear DNA (average F(ST) = 0.095). Unlike nuclear DNA, cpDNA showed no pattern of isolation by adaptation; cpDNA differentiation was, however, inversely correlated with the number of additions (nutrients and lime) that each plot had received. We suggest that natural selection is restricting pollen flow among plots, whereas nutrient additions are increasing seed flow and genetic diversity by facilitating the successful germination and growth of immigrant seeds. This study highlights the importance of considering all potential gene flow mechanisms when investigating determinants of spatial genetic structure, and cautions against the widespread assumption that pollen flow is more important than seed flow for population connectivity in wind-pollinated species.
Collapse
Affiliation(s)
- Joanna R Freeland
- Department of Biology, Trent University, Peterborough, Ontario, Canada.
| | | | | |
Collapse
|
14
|
Silvertown J, Cook L, Cameron R, Dodd M, McConway K, Worthington J, Skelton P, Anton C, Bossdorf O, Baur B, Schilthuizen M, Fontaine B, Sattmann H, Bertorelle G, Correia M, Oliveira C, Pokryszko B, Ożgo M, Stalažs A, Gill E, Rammul Ü, Sólymos P, Féher Z, Juan X. Citizen science reveals unexpected continental-scale evolutionary change in a model organism. PLoS One 2011; 6:e18927. [PMID: 21556137 PMCID: PMC3083392 DOI: 10.1371/journal.pone.0018927] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 03/11/2011] [Indexed: 11/18/2022] Open
Abstract
Organisms provide some of the most sensitive indicators of climate change and evolutionary responses are becoming apparent in species with short generation times. Large datasets on genetic polymorphism that can provide an historical benchmark against which to test for recent evolutionary responses are very rare, but an exception is found in the brown-lipped banded snail (Cepaea nemoralis). This species is sensitive to its thermal environment and exhibits several polymorphisms of shell colour and banding pattern affecting shell albedo in the majority of populations within its native range in Europe. We tested for evolutionary changes in shell albedo that might have been driven by the warming of the climate in Europe over the last half century by compiling an historical dataset for 6,515 native populations of C. nemoralis and comparing this with new data on nearly 3,000 populations. The new data were sampled mainly in 2009 through the Evolution MegaLab, a citizen science project that engaged thousands of volunteers in 15 countries throughout Europe in the biggest such exercise ever undertaken. A known geographic cline in the frequency of the colour phenotype with the highest albedo (yellow) was shown to have persisted and a difference in colour frequency between woodland and more open habitats was confirmed, but there was no general increase in the frequency of yellow shells. This may have been because snails adapted to a warming climate through behavioural thermoregulation. By contrast, we detected an unexpected decrease in the frequency of Unbanded shells and an increase in the Mid-banded morph. Neither of these evolutionary changes appears to be a direct response to climate change, indicating that the influence of other selective agents, possibly related to changing predation pressure and habitat change with effects on micro-climate.
Collapse
Affiliation(s)
- Jonathan Silvertown
- Department of Life Sciences, The Open University, Milton Keynes, United Kingdom.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Araya YN, Silvertown J, Gowing DJ, McConway KJ, Linder HP, Midgley G. A fundamental, eco-hydrological basis for niche segregation in plant communities. New Phytol 2011; 189:253-258. [PMID: 20868394 DOI: 10.1111/j.1469-8137.2010.03475.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
• Ecologists still puzzle over how plant species manage to coexist with one another while competing for the same essential resources. The classic answer for animal communities is that species occupy different niches, but how plants do this is more difficult to determine. We previously found niche segregation along fine-scale hydrological gradients in European wet meadows and proposed that the mechanism might be a general one, especially in communities that experience seasonal saturation. • We quantified the hydrological niches of 96 species from eight fynbos communities in the biodiversity hotspot of the Cape Floristic Region, South Africa and 99 species from 18 lowland wet meadow communities in the UK. Niche overlap was computed for all combinations of species. • Despite the extreme functional and phylogenetic differences between the fynbos and wet meadow communities, an identical trade-off (i.e. specialization of species towards tolerance of aeration and/or drying stress) was found to cause segregation along fine-scale hydrological gradients. • This study not only confirms the predicted generality of hydrological niche segregation, but also emphasizes its importance for structuring plant communities. Eco-hydrological niche segregation will have implications for conservation in habitats that face changing hydrology caused by water abstraction and climate change.
Collapse
Affiliation(s)
- Yoseph N Araya
- Department of Life Sciences, Open University, Milton Keynes, UK.
| | | | | | | | | | | |
Collapse
|
16
|
Silvertown J, Tallowin J, Stevens C, Power SA, Morgan V, Emmett B, Hester A, Grime PJ, Morecroft M, Buxton R, Poulton P, Jinks R, Bardgett R. Environmental myopia: a diagnosis and a remedy. Trends Ecol Evol 2010; 25:556-61. [DOI: 10.1016/j.tree.2010.06.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 06/26/2010] [Accepted: 06/28/2010] [Indexed: 10/19/2022]
|
17
|
Freeland JR, Biss P, Conrad KF, Silvertown J. Selection pressures have caused genome-wide population differentiation of Anthoxanthum odoratum despite the potential for high gene flow. J Evol Biol 2010; 23:776-82. [PMID: 20163507 DOI: 10.1111/j.1420-9101.2010.01947.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The extent to which divergent selection can drive genome-wide population differentiation remains unclear. Theory predicts that in the face of ongoing gene flow, population differentiation should be apparent only at those markers that are directly or indirectly (i.e. through linkage) under selection. However, if reproductive barriers limit gene flow, genome-wide population differentiation may occur even in geographically proximate populations. Some insight into the link between selection and genetic differentiation in the presence of ongoing gene flow can come from long-term experiments such as The Park Grass Experiment, which has been running for over 150 years, and provides a unique example of a heterogeneous environment with a long and detailed history. Fertilizer treatments applied in the Park Grass Experiment have led to rapid evolutionary change in sweet vernal grass Anthoxanthum odoratum, but until now, nothing was known of how these changes would be reflected in neutral molecular markers. We have genotyped ten A. odoratum populations from the Park Grass Experiment using Amplified Fragment Length Polymorphisms (AFLPs). Our data show that nutrient additions have resulted in genome-wide divergence among plots despite the high potential for ongoing gene flow. This provides a well-documented example of concordance between genomes and environmental conditions that has arisen in continuous populations across a time span of fewer than 75 generations.
Collapse
Affiliation(s)
- J R Freeland
- Department of Biology, Trent University, Peterborough, ON, Canada.
| | | | | | | |
Collapse
|
18
|
Abstract
A citizen scientist is a volunteer who collects and/or processes data as part of a scientific enquiry. Projects that involve citizen scientists are burgeoning, particularly in ecology and the environmental sciences, although the roots of citizen science go back to the very beginnings of modern science itself.
Collapse
Affiliation(s)
- Jonathan Silvertown
- Department of Life Sciences, The Open University, Walton Hall, Milton Keynes, UK.
| |
Collapse
|
19
|
Silvertown J, Biss PM, Freeland J. Community genetics: resource addition has opposing effects on genetic and species diversity in a 150-year experiment. Ecol Lett 2009; 12:165-70. [PMID: 19143828 DOI: 10.1111/j.1461-0248.2008.01273.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We used the Park Grass Experiment, begun in 1856, to test alternative hypotheses about the relationship between genetic diversity and plant species diversity. The niche variation hypothesis predicts that populations with few interspecific competitors and hence broader niches are expected to contain greater genetic diversity. The coexistence hypothesis predicts that genetic diversity within species favours coexistence among species and therefore species and genetic diversity should be positively correlated. Amplified Fragment Length Polymorphism (AFLP) markers were used to measure the genetic diversity of populations of Anthoxanthum odoratum growing in 10 plots of differing species richness that lie along resource and soil pH gradients. Genetic diversity in A. odoratum was positively correlated with the number of resources added to a plot, but not correlated with species richness. However, separate analyses have shown a negative correlation between resource addition and species richness at Park Grass and elsewhere, so genetic and species diversity appear to respond in opposite directions.
Collapse
Affiliation(s)
- Jonathan Silvertown
- Department of Life Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.
| | | | | |
Collapse
|
20
|
Abstract
The global extinction of species proceeds through the erosion of local populations. Using a 60-year time series of annual sighting records of plant species, we studied the correlates of local extinction risk associated with a risk of species extinction in the Park Grass Experiment where plants received long-term exposure to nutrient enrichment, soil acidification, and reductions in habitat size. We used multivariate linear models to assess how extrinsic threats and life history traits influence extinction risk. We investigated effects of four extrinsic threats (nitrogen enrichment, productivity, acidification, and plot size) as well as 11 life history traits (month of earliest flowering, flowering duration, stress tolerance, ruderalness [plant species' ability to cope with habitat disturbance], plant height, diaspore mass, seed bank, life form, dispersal mode, apomixis [the ability for a species to reproduce asexuall through seeds], and mating system). Extinction risk was not influenced by plant family. All of the 11 life history traits except life form and all threat variables influenced extinction risk but always via interactions which typically involved one threat variable and one life history trait. We detected comparatively few significant interactions between life history traits, and the interacting traits compensated for each other. These results suggest that simple predictions about extinction risk based on species' traits alone will often fail. In contrast, understanding the interactions between extrinsic threats and life history traits will allow us to make more accurate predictions of extinctions.
Collapse
Affiliation(s)
- Hélène Fréville
- Ecology and Evolution Research Group, Department of Biological Sciences, Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom.
| | | | | | | |
Collapse
|
21
|
Abstract
R. H. Whittaker's idea that plant diversity can be divided into a hierarchy of spatial components from alpha at the within-habitat scale through beta for the turnover of species between habitats to gamma along regional gradients implies the underlying existence of alpha, beta, and gamma niches. We explore the hypothesis that the evolution of alpha, beta, and gamma niches is also hierarchical, with traits that define the alpha niche being labile, while those defining beta and gamma niches are conservative. At the alpha level we find support for the hypothesis in the lack of close significant phylogenetic relationship between meadow species that have similar alpha niches. In a second test, alpha niche overlap based on a variety of traits is compared between congeners and noncongeners in several communities; here, too, there is no evidence of a correlation between alpha niche and phylogeny. To test whether beta and gamma niches evolve conservatively, we reconstructed the evolution of relevant traits on evolutionary trees for 14 different clades. Tests against null models revealed a number of instances, including some in island radiations, in which habitat (beta niche) and elevational maximum (an aspect of the gamma niche) showed evolutionary conservatism.
Collapse
Affiliation(s)
- Jonathan Silvertown
- Department of Biological Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.
| | | | | | | | | |
Collapse
|
22
|
Silvertown J, McConway K, Gowing D, Dodd M, Fay MF, Joseph JA, Dolphin K. Absence of phylogenetic signal in the niche structure of meadow plant communities. Proc Biol Sci 2006; 273:39-44. [PMID: 16519232 PMCID: PMC1560004 DOI: 10.1098/rspb.2005.3288] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2005] [Accepted: 08/04/2005] [Indexed: 11/12/2022] Open
Abstract
A significant proportion of the global diversity of flowering plants has evolved in recent geological time, probably through adaptive radiation into new niches. However, rapid evolution is at odds with recent research which has suggested that plant ecological traits, including the beta- (or habitat) niche, evolve only slowly. We have quantified traits that determine within-habitat alpha diversity (alpha niches) in two communities in which species segregate on hydrological gradients. Molecular phylogenetic analysis of these data shows practically no evidence of a correlation between the ecological and evolutionary distances separating species, indicating that hydrological alpha niches are evolutionarily labile. We propose that contrasting patterns of evolutionary conservatism for alpha- and beta-niches is a general phenomenon necessitated by the hierarchical filtering of species during community assembly. This determines that species must have similar beta niches in order to occupy the same habitat, but different alpha niches in order to coexist.
Collapse
Affiliation(s)
- Jonathan Silvertown
- Department of Biological Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK.
| | | | | | | | | | | | | |
Collapse
|
23
|
Silvertown J, Servaes C, Biss P, Macleod D. Reinforcement of reproductive isolation between adjacent populations in the Park Grass Experiment. Heredity (Edinb) 2005; 95:198-205. [PMID: 15999138 DOI: 10.1038/sj.hdy.6800710] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
It has been debated, ever since Charles Darwin and Alfred Russell Wallace disagreed about the matter, whether natural selection plays a role in reinforcing reproductive isolation during the earliest stages of speciation. Recent theory suggests that it can do so, but until now the empirical evidence has conspicuously lacked a case in which reinforcement has actually been observed to split a population. We show that this has occurred at least once in populations of the grass Anthoxanthum odoratum growing in the Park Grass Experiment where flowering time has shifted at the boundaries between plots. As a consequence, gene flow via pollen has been severely limited and adjacent populations that had a common origin at the start of the experiment in 1856 have now diverged at neutral marker loci.
Collapse
Affiliation(s)
- J Silvertown
- Department of Biological Sciences, Ecology and Evolution Research Group, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK.
| | | | | | | |
Collapse
|
24
|
Crawley MJ, Johnston AE, Silvertown J, Dodd M, de Mazancourt C, Heard MS, Henman DF, Edwards GR. Determinants of species richness in the Park Grass Experiment. Am Nat 2005; 165:179-92. [PMID: 15729649 DOI: 10.1086/427270] [Citation(s) in RCA: 198] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2004] [Accepted: 07/21/2004] [Indexed: 11/03/2022]
Abstract
The Park Grass Experiment at Rothamsted in southeast England was started in 1856, making it the longest-running experiment in plant ecology anywhere in the world. Experimental inputs include a range of fertilizers (nitrogen, phosphorus, potassium, and organic manures) applied annually, with lime applied occasionally, and these have led to an increase in biomass and, where nitrogen was applied in the form of ammonium sulfate, to substantial decreases in soil pH. The number of species per plot varies from three to 44 per 200 m(2), affording a unique opportunity to study the determinants of plant species richness and to estimate the effect sizes attributable to different factors. The response of species richness to biomass depends on the amount and type of nitrogen applied; richness declined monotonically with increasing biomass on plots receiving no nitrogen or receiving nitrogen in the form of sodium nitrate, but there was no relationship between species richness and biomass on plots acidified by ammonium sulfate application. The response to lime also depended on the type of nitrogen applied; there was no relationship between lime treatment and species richness, except in plots receiving nitrogen in the form of ammonium sulfate, where species richness increased sharply with increasing soil pH. The addition of phosphorus reduced species richness, and application of potassium along with phosphorus reduced species richness further, but the biggest negative effects were when nitrogen and phosphorus were applied together. The analysis demonstrates how multiple factors contribute to the observed diversity patterns and how environmental regulation of species pools can operate at the same spatial and temporal scale as biomass effects.
Collapse
Affiliation(s)
- M J Crawley
- Department of Biological Sciences, Imperial College London, Silwood Park, Ascot, Berkshire, SL5 7PY, United Kingdom.
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Abstract
Sustainable exploitation is widely advocated as a strategy for reconciling economic pressures upon natural habitats with nature conservation. Two recent papers examine different aspects of the sustainability of the nut harvest on wild populations of Brazil nut trees Bertholletia excelsa in Amazonia. Peres et al. find that many populations of the Brazil nut tree lack juvenile trees and are not regenerating. In a socioeconomic study, Escobal and Aldana find that nut-gathering provides insufficient income on its own to support nut-gatherers and that their other income-raising activities damage the forest. The existence of a market for rainforest products is, therefore, not sufficient on its own to prevent habitat destruction or the overexploitation of the resource and a more sophisticated approach to sustainability is required. Development of a market in ethically traded Brazil nuts might be one solution.
Collapse
Affiliation(s)
- Jonathan Silvertown
- Department of Biological Sciences, The Open University, Walton Hall, Milton Keynes, UK, MK7 6AA.
| |
Collapse
|
26
|
|
27
|
|
28
|
Silvertown J, McConway K, Hughes Z, Biss P, Macnair M, Lutman P. Ecological and Genetic Correlates of Long‐Term Population Trends in the Park Grass Experiment. Am Nat 2002; 160:409-20. [DOI: 10.1086/342071] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
29
|
Abstract
The hierarchy of plant size often present in dense populations of plants and the close correlation found between size and fecundity can result in an unequal distribution of fecundity, which reduces the ratio of effective population size/census number (Ne/N). Such an effect has been found previously in annuals, but no study has hitherto tested for the effect in the lifetime fecundity variation of a perennial population. We use the demographically stable size distribution to be found in natural, wave-regenerating populations of balsam fir, Abies balsamea, in order to estimate Ne/N. In both wave-regenerating and normal forests our estimated values of Ne/N were about twice those previously reported for annuals. We suggest that fecundity variance is expected to be smaller in trees and other long-lived perennials than in annuals because density-dependent mortality operates more strongly in the prereproductive phase of long-lived plants.
Collapse
Affiliation(s)
- M E Dodd
- Ecology and Evolution Research Group, Department of Biological Sciences, Open University, Milton Keynes MK7 6AA, UK
| | | |
Collapse
|
30
|
Silvertown J, Mcconway KJ, Dodd ME, Chase MW. "FLEXIBILITY" AS A TRAIT AND METHODOLOGICAL ISSUES IN SPECIES DIVERSITY VARIATION AMONG ANGIOSPERM FAMILIES. Evolution 2000. [DOI: 10.1111/j.0014-3820.2000.tb00110.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
31
|
Silvertown J, McConway KJ, Dodd ME, Chase MW. "Flexibility" as a trait and methodological issues in species diversity variation among angiosperm families. Evolution 2000; 54:1066-8. [PMID: 10937283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Affiliation(s)
- J Silvertown
- Department of Biological Sciences, Open University, Milton Keynes, United Kingdom.
| | | | | | | |
Collapse
|
32
|
Abstract
Ecological theory provides two contrasting predictions about the characteristics of the species combining to form communities. Classical competition theory states that they will be less similar than expected by chance, whilst the environmental structuring hypothesis states that they will be more similar. We investigated these predictions by applying phylogenetic methods of analysis (PICs) to a grassland community, examining species on the basis of their traits. At the scale of investigation most useful in making predictions about the presence and abundance of species (the community level, the species forming the community were more similar than would be expected by chance. The use of PICs resulted in a more sensitive test than if phylogeny had been ignored, allowing the detection of effects that would otherwise have been overlooked or underestimated. Selected traits from the PICs analysis were used to develop a predictive model of community membership using discriminant analysis. This correctly identified species in the pool which were present in the community but failed to predict absences accurately, implying that dispersal limitation may operate in the community.
Collapse
Affiliation(s)
- R Tofts
- Department of Biology, The Open University, Milton Keynes, UK
| | | |
Collapse
|
33
|
Silvertown J, McConway KJ, Dodd ME, Chase MW. “FLEXIBILITY” AS A TRAIT AND METHODOLOGICAL ISSUES IN SPECIES DIVERSITY VARIATION AMONG ANGIOSPERM FAMILIES. Evolution 2000. [DOI: 10.1554/0014-3820(2000)054[1066:faatam]2.3.co;2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
34
|
Abstract
It is an axiom of life-history theory that reproduction involves age-specific costs in terms of survival or future reproduction. The measurement of costs of reproduction in plants is difficult, and few field studies have measured these costs in terms of fitness or demographic components, thus creating a hiatus between theory and data. In this article, we describe methods for overcoming the problem, illustrated by a field study of balsam fir. We used serial correlation and a permutation test to detect growth costs of reproduction and show how these translate into demographic costs when relative tree size (and therefore growth) is critical to survival. Using chronosequences, we reconstructed the age- and size-specific dynamics of a subalpine population of Abies balsamea. A matrix model describing these dynamics was then used to estimate age- and size-specific probabilities of future survival to maturity ([Formula: see text]). By using a regression model of the relationship between tree size, age, and [Formula: see text], we were able to estimate the maximum age-specific demographic cost of reproduction for trees of all ages. The shape of the age-specific cost curve for A. balsamea may explain why, contrary to a previously published hypothesis, age at first reproduction in A. balsamea does not vary between wave-regenerating and normal populations.
Collapse
|
35
|
Silvertown J, Dodd ME, Gowing DJG, Mountford JO. Hydrologically defined niches reveal a basis for species richness in plant communities. Nature 1999. [DOI: 10.1038/21877] [Citation(s) in RCA: 384] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
36
|
Dodd ME, Silvertown J, Chase MW. Phylogenetic Analysis of Trait Evolution and Species Diversity Variation among Angiosperm Families. Evolution 1999. [DOI: 10.2307/2640713] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
37
|
Affiliation(s)
- Jonathan Silvertown
- Ecology & Conservation Research Group, Biology Department, Open University, Milton Keynes, MK7 6AA, UK
| | - Mike Dodd
- Ecology & Conservation Research Group, Biology Department, Open University, Milton Keynes, MK7 6AA, UK
| |
Collapse
|
38
|
|
39
|
Valverde T, Silvertown J. An Integrated Model of Demography, Patch Dynamics and Seed Dispersal in a Woodland Herb, Primula vulgaris. OIKOS 1997. [DOI: 10.2307/3546517] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
40
|
|
41
|
|
42
|
|
43
|
Clear Hill B, Silvertown J. Higher-order interaction between molluscs and sheep affecting seedling numbers in grassland. Acta Oecologica 1997. [DOI: 10.1016/s1146-609x(97)80043-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
44
|
Valverde T, Silvertown J. Spatial Variation in the Seed Ecology of a Woodland Herb (Primula vulgaris) in Relation to Light Environment. Funct Ecol 1995. [DOI: 10.2307/2389993] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
45
|
Silvertown J, Dodd M, McConway K, Crawley M, Potts J. Species diversity and stability in grassland. Trends Ecol Evol 1995; 10:287-8. [PMID: 21237039 DOI: 10.1016/0169-5347(95)90017-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- J Silvertown
- Biology Dept, Open University, Milton Keynes, UK MK7 6AA
| | | | | | | | | |
Collapse
|
46
|
Bullock JM, Hill BC, Silvertown J, Sutton M. Gap Colonization as a Source of Grassland Community Change: Effects of Gap Size and Grazing on the Rate and Mode of Colonization by Different Species. OIKOS 1995. [DOI: 10.2307/3546229] [Citation(s) in RCA: 142] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
47
|
Enright NJ, Franco M, Silvertown J. Comparing plant life histories using elasticity analysis: the importance of life span and the number of life-cycle stages. Oecologia 1995; 104:79-84. [PMID: 28306916 DOI: 10.1007/bf00365565] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/1994] [Accepted: 04/21/1995] [Indexed: 11/26/2022]
Abstract
Recent studies have used transition matrix elasticity analysis to investigate the relative role of survival (L), growth (G) and fecundity (F) in determining the estimated rate of population increase for perennial plants. The relative importance of these three variables has then been used as a framework for comparing patterns of plant life history in a triangular parameter space. Here we analyse the ways in which the number of life-cycle stages chosen to describe a species (transition matrix dimensionality) might influence the interpretation of such comparisons. Because transition matrix elements describing survival ("stasis") and growth are not independent, the number of stages used to describe a species influences their relative contribution to the population growth rate. Reduction in the number of stages increases the apparent importance of stasis relative to growth, since each becomes broader and fewer individuals make the transition to the next stage per unit time period. Analysis of a test matrix for a hypothetical tree species divided into 4-32 life-cycle stages confirms this. If the number of stages were defined in relation to species longevity so that mean residence time in each stage were approximately constant, then the elasticity of G would reflect the importance of relative growth rate to λ. An alternative, and simpler, approach to ensure comparability of results between species may be to use the same number of stages regardless of species longevity. Published studies for both herbaceous and woody species have tended to use relatively few stages to describe life cycles (herbs: n=45, [Formula: see text]; woody plants: n=21, [Formula: see text]) and so approximate this approach. By using the same number of stages regardless of longevities, the position of species along the G-L side of the triangular parameter space largely reflects differences in longevity. The extent of variation in elasticity for L, G and F within and between species may also be related to factors such as successional status and habitat. For example, the shade-tolerant woody species, Araucaria cunninghamii, shows greater importance for stasis (L), while the gap-phase congener species, Araucaria hunsteinii, shows higher values for G (although values are likely to vary with the stage of stand development).
Collapse
Affiliation(s)
- N J Enright
- Department of Geography, University of Melbourne, 3052, Parkville, Victoria, Australia
| | - M Franco
- Centro de Ecologia, Universidad Nacional Autonoma de México, Apartado Postal 70-275, 04510, México, D.F., México
| | - J Silvertown
- Biology Department, Open University, MK7 6AA, Milton Keynes, UK
| |
Collapse
|
48
|
|
49
|
Bullock JM, Hill BC, Dale MP, Silvertown J. An Experimental Study of the Effects of Sheep Grazing on Vegetation Change in a Species-Poor Grassland and the Role of Seedling Recruitment Into Gaps. J Appl Ecol 1994. [DOI: 10.2307/2404445] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
50
|
|