Genetic diversity enhances restoration success by augmenting ecosystem services - PubMed (original) (raw)
Genetic diversity enhances restoration success by augmenting ecosystem services
Laura K Reynolds et al. PLoS One. 2012.
Abstract
Disturbance and habitat destruction due to human activities is a pervasive problem in near-shore marine ecosystems, and restoration is often used to mitigate losses. A common metric used to evaluate the success of restoration is the return of ecosystem services. Previous research has shown that biodiversity, including genetic diversity, is positively associated with the provision of ecosystem services. We conducted a restoration experiment using sources, techniques, and sites similar to actual large-scale seagrass restoration projects and demonstrated that a small increase in genetic diversity enhanced ecosystem services (invertebrate habitat, increased primary productivity, and nutrient retention). In our experiment, plots with elevated genetic diversity had plants that survived longer, increased in density more quickly, and provided more ecosystem services (invertebrate habitat, increased primary productivity, and nutrient retention). We used the number of alleles per locus as a measure of genetic diversity, which, unlike clonal diversity used in earlier research, can be applied to any organism. Additionally, unlike previous studies where positive impacts of diversity occurred only after a large disturbance, this study assessed the importance of diversity in response to potential environmental stresses (high temperature, low light) along a water-depth gradient. We found a positive impact of diversity along the entire depth gradient. Taken together, these results suggest that ecosystem restoration will significantly benefit from obtaining sources (transplants or seeds) with high genetic diversity and from restoration techniques that can maintain that genetic diversity.
Conflict of interest statement
Competing Interests: The authors have declared that no competing interests exist.
Figures
Figure 1. Zostera marina seeds were collected from Mobjack Bay and the York River in Chesapeake Bay and from South Bay, part of the Virginia coastal bay system.
Seeds were planted in Hog Island Bay, also part of the Virginia coastal bay system in plots as either individual sources or as plots with all seed sources combined. Plots planted with seeds from either Mobjack Bay or the York River had a lower overall genetic diversity (measured by alleles per locus) than plots planted from either South Bay or from all three seed sources combined.
Figure 2. The relationship between plant density (A), invertebrate density (B), and areal productivity (C) during the peak growing season (June) was regressed against plot genetic diversity.
Figure 3. Experimental Zostera marina plots were planted in Hog Island Bay in two levels of genetic diversity: relatively high (4.4 alleles per locus ±0.3 s.e.) and relatively low (3.5 alleles per locus ±0.3 s.e.).
During the peak summer growth (June and July), plant characteristics [density (A) and shoot height (B)] and measured ecosystem services [habitat function estimated as invertebrate density (C) and areal productivity (D)] were measured, and differences between high diversity and low diversity plots were analyzed with a t-test. Error bars represent standard error. Dots represent the mean of plots from individual seed sources.
Figure 4. Experimental Zostera marina plots were planted in Hog Island Bay over a depth gradient of 0.8 m (range −0.78–1.5 MSL).
Environmental conditions [light (A) and temperature (B)] varied with depth and resulted in differences in plant density (C). Plots at a depth less than 1 m and plots with a depth greater than 1.4 m had lower densities, while mid-depth plots had high densities that increased each year. Plots, replicated at each depth, were assigned to one of two levels of genetic diversity: relatively high (4.4 alleles per locus ±0.3 s.e.) and relatively low (3.5 alleles per locus ±0.3 s.e.). (D) Differences in density between the high diversity and low diversity plots were analyzed with a chi-square test (expected value of 0). Plants at the deepest depths died during the second growing season; therefore, differences were analyzed for the first year, while all plots had live plants, independently. Arrows indicate the timing of maximum density difference between high and low diversity plots.
Figure 5. Experimental Zostera marina plots were planted in Hog Island Bay in two levels of genetic diversity: relatively high (4.4 alleles per locus ±0.3 s.e.) and relatively low (3.5 alleles per locus ±0.3 s.e.).
Plots were replicated at depth. Plots at a depth less than 1 m were apparently heat stressed had reduced densities, while plots at depths between 1 and 1.4 m had high densities that increased over time. For each sampling date, a difference in density between high diversity and low diversity plots was calculated at each depth. A paired t-test (paired at sampling date) was used to determine if there was a greater effect of diversity on density at the different stress levels. The solid line is a 1∶1 line representing no differences in the effect of diversity between the two depths. The grey areas represent samples where the effect of genetic diversity on plant density was not significant.
References
- Society for Ecological Restoration International Science and Policy Working Group. The SER International Primer on Ecological Restoration. Tucson: Society for Ecological Restoration International. 2004. Available: http://www.ser.org/content/ecological_restoration_primer.asp. Accessed 10 May 2012.
- Kinzig AP, Pacala SW, Tilman D. The functional consequences of biodiversity: empirical progress and theoretical extensions. Princeton: Princeton Univ Pr. 2001.
- Loreau M, Naeem S, Inchausti P. Biodiversity and ecosystem functioning: synthesis and perspectives. Oxford: Oxford University Press. 2002.
- Hooper DU, Chapin FS, Ewel JJ, Hector A, Inchausti P, et al. Effects of biodiversity on ecosystem functioning: a consensus of current knowledge. Ecol Monog. 2005;75:3–35.
- Ruiz-Jaen MC, Mitchell AT. Restoration success: How is it being measured? Rest Ecol. 2005;13:569–577.
Publication types
MeSH terms
LinkOut - more resources
Full Text Sources