Limits...
Mutualism Disruption Threatens Global Plant Biodiversity: A Systematic Review.

Aslan CE, Zavaleta ES, Tershy B, Croll D - PLoS ONE (2013)

Bottom Line: Extinctions of mutualist partners can create "widow" species, which may face reduced ecological fitness.Hypothetically, such mutualism disruptions could have cascading effects on biodiversity by causing additional species coextinctions.Although uncertainty is high, there is evidence that mutualism disruption directly threatens significant biodiversity in some geographic regions.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Studies, University of California Santa Cruz, Santa Cruz, California, United States of America.

ABSTRACT

Background: As global environmental change accelerates, biodiversity losses can disrupt interspecific interactions. Extinctions of mutualist partners can create "widow" species, which may face reduced ecological fitness. Hypothetically, such mutualism disruptions could have cascading effects on biodiversity by causing additional species coextinctions. However, the scope of this problem - the magnitude of biodiversity that may lose mutualist partners and the consequences of these losses - remains unknown.

Methodology/principal findings: We conducted a systematic review and synthesis of data from a broad range of sources to estimate the threat posed by vertebrate extinctions to the global biodiversity of vertebrate-dispersed and -pollinated plants. Though enormous research gaps persist, our analysis identified Africa, Asia, the Caribbean, and global oceanic islands as geographic regions at particular risk of disruption of these mutualisms; within these regions, percentages of plant species likely affected range from 2.1-4.5%. Widowed plants are likely to experience reproductive declines of 40-58%, potentially threatening their persistence in the context of other global change stresses.

Conclusions: Our systematic approach demonstrates that thousands of species may be impacted by disruption in one class of mutualisms, but extinctions will likely disrupt other mutualisms, as well. Although uncertainty is high, there is evidence that mutualism disruption directly threatens significant biodiversity in some geographic regions. Conservation measures with explicit focus on mutualistic functions could be necessary to bolster populations of widowed species and maintain ecosystem functions.

No MeSH data available.


A review of pollinator exclusion studies yielded weighted mean seed set reductions for widows previously pollinated by different vertebrate classes.a) Seed set reductions after bat exclusion for bat-pollinated plants. b) Seed set reductions after nonvolant mammal exclusion for nonvolant mammal-pollinated plants. c) Seed set reductions after bird exclusion for bird-pollinated plants. d) Seed set reductions after lizard exclusion for lizard-pollinated plants. Bars depict weighted means. Vertical lines represent standard error. The minimum seed set observed in any exclusion study is indicated with an asterisk (*); this is the minimum predicted effect of loss of vertebrate pollinators for a given plant species. Bold numbers at the top of each bar provide the number of independent publications used to calculate each weighted mean.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3686776&req=5

pone-0066993-g003: A review of pollinator exclusion studies yielded weighted mean seed set reductions for widows previously pollinated by different vertebrate classes.a) Seed set reductions after bat exclusion for bat-pollinated plants. b) Seed set reductions after nonvolant mammal exclusion for nonvolant mammal-pollinated plants. c) Seed set reductions after bird exclusion for bird-pollinated plants. d) Seed set reductions after lizard exclusion for lizard-pollinated plants. Bars depict weighted means. Vertical lines represent standard error. The minimum seed set observed in any exclusion study is indicated with an asterisk (*); this is the minimum predicted effect of loss of vertebrate pollinators for a given plant species. Bold numbers at the top of each bar provide the number of independent publications used to calculate each weighted mean.

Mentions: The observed and estimated impact of mutualism disruption on plant reproduction varies by species. We conducted a comprehensive literature review of vertebrate pollinator exclusion studies to estimate the average seed set reduction likely to result from extinction of all vertebrate pollinators of any given angiosperm species (Figs. 2,3; Text S1). These studies had quantified the percent of seed set attributable to specific vertebrate classes by excluding that class but not other potential pollinators (e.g., invertebrates). Our use of these studies enabled us to separate the proportion of seed set generated by vertebrate pollination from seed set attributable to self-fertilization and invertebrates. For each vertebrate class, we calculated an average, weighted by sample size, of the percentage reduction in seed set across all studies relevant to that class. The results of these weighted averages are midrange estimates of seed set reduction in the absence of each vertebrate class (Fig. 3).


Mutualism Disruption Threatens Global Plant Biodiversity: A Systematic Review.

Aslan CE, Zavaleta ES, Tershy B, Croll D - PLoS ONE (2013)

A review of pollinator exclusion studies yielded weighted mean seed set reductions for widows previously pollinated by different vertebrate classes.a) Seed set reductions after bat exclusion for bat-pollinated plants. b) Seed set reductions after nonvolant mammal exclusion for nonvolant mammal-pollinated plants. c) Seed set reductions after bird exclusion for bird-pollinated plants. d) Seed set reductions after lizard exclusion for lizard-pollinated plants. Bars depict weighted means. Vertical lines represent standard error. The minimum seed set observed in any exclusion study is indicated with an asterisk (*); this is the minimum predicted effect of loss of vertebrate pollinators for a given plant species. Bold numbers at the top of each bar provide the number of independent publications used to calculate each weighted mean.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3686776&req=5

pone-0066993-g003: A review of pollinator exclusion studies yielded weighted mean seed set reductions for widows previously pollinated by different vertebrate classes.a) Seed set reductions after bat exclusion for bat-pollinated plants. b) Seed set reductions after nonvolant mammal exclusion for nonvolant mammal-pollinated plants. c) Seed set reductions after bird exclusion for bird-pollinated plants. d) Seed set reductions after lizard exclusion for lizard-pollinated plants. Bars depict weighted means. Vertical lines represent standard error. The minimum seed set observed in any exclusion study is indicated with an asterisk (*); this is the minimum predicted effect of loss of vertebrate pollinators for a given plant species. Bold numbers at the top of each bar provide the number of independent publications used to calculate each weighted mean.
Mentions: The observed and estimated impact of mutualism disruption on plant reproduction varies by species. We conducted a comprehensive literature review of vertebrate pollinator exclusion studies to estimate the average seed set reduction likely to result from extinction of all vertebrate pollinators of any given angiosperm species (Figs. 2,3; Text S1). These studies had quantified the percent of seed set attributable to specific vertebrate classes by excluding that class but not other potential pollinators (e.g., invertebrates). Our use of these studies enabled us to separate the proportion of seed set generated by vertebrate pollination from seed set attributable to self-fertilization and invertebrates. For each vertebrate class, we calculated an average, weighted by sample size, of the percentage reduction in seed set across all studies relevant to that class. The results of these weighted averages are midrange estimates of seed set reduction in the absence of each vertebrate class (Fig. 3).

Bottom Line: Extinctions of mutualist partners can create "widow" species, which may face reduced ecological fitness.Hypothetically, such mutualism disruptions could have cascading effects on biodiversity by causing additional species coextinctions.Although uncertainty is high, there is evidence that mutualism disruption directly threatens significant biodiversity in some geographic regions.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Studies, University of California Santa Cruz, Santa Cruz, California, United States of America.

ABSTRACT

Background: As global environmental change accelerates, biodiversity losses can disrupt interspecific interactions. Extinctions of mutualist partners can create "widow" species, which may face reduced ecological fitness. Hypothetically, such mutualism disruptions could have cascading effects on biodiversity by causing additional species coextinctions. However, the scope of this problem - the magnitude of biodiversity that may lose mutualist partners and the consequences of these losses - remains unknown.

Methodology/principal findings: We conducted a systematic review and synthesis of data from a broad range of sources to estimate the threat posed by vertebrate extinctions to the global biodiversity of vertebrate-dispersed and -pollinated plants. Though enormous research gaps persist, our analysis identified Africa, Asia, the Caribbean, and global oceanic islands as geographic regions at particular risk of disruption of these mutualisms; within these regions, percentages of plant species likely affected range from 2.1-4.5%. Widowed plants are likely to experience reproductive declines of 40-58%, potentially threatening their persistence in the context of other global change stresses.

Conclusions: Our systematic approach demonstrates that thousands of species may be impacted by disruption in one class of mutualisms, but extinctions will likely disrupt other mutualisms, as well. Although uncertainty is high, there is evidence that mutualism disruption directly threatens significant biodiversity in some geographic regions. Conservation measures with explicit focus on mutualistic functions could be necessary to bolster populations of widowed species and maintain ecosystem functions.

No MeSH data available.