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Abstract The diversity of primary producers strongly affects the structure and diversity of species assemblages at other trophic levels. However, limited knowledge exists of how plant diversity effects at small spatial scales propagate to consumer communities at larger spatial scales. We assessed arthropod community β and γ‐diversity in response to experimentally manipulated plant community richness in two long‐term grassland biodiversity experiments (Jena, Germany and Cedar Creek, USA) replicated over two years. We calculated arthropod species turnover among all plot combinations (β‐diversity), and accumulated number of arthropod species occurring on (1) all pairwise plot combinations and (2) 40 randomly selected six‐plot combinations (γ‐diversity). The components of arthropod diversity were tested against two measures of plant diversity, namely average plant α‐diversity () and the average difference in plant α‐diversity between plots (ΔPSR). Whereas points to the overall importance of plant α‐diversity for arthropod community turnover and diversity on a larger scale, ΔPSR represents the role of habitat heterogeneity. We demonstrate that arthropod γ‐diversity is supported by high, homogeneous plant α‐diversity, despite lower arthropod β‐diversity among high‐ compared to low‐diversity plant communities. We also show that, in six‐plot combinations, average plant α‐diversity has a positive influence on arthropod γ‐diversity only when homogeneity in plant α‐diversity is also high. Varying heterogeneity in six‐plot combinations showed that combinations consisting solely of plots with an intermediate level of plant α‐diversity support a higher number of arthropod species compared to combinations that contain a mix of high‐ and low‐diversity plots. In fact, equal levels of arthropod diversity were found for six‐plot combinations with only intermediate or high plant α‐diversity, due to saturating benefits of local and larger‐scale plant diversity for higher trophic levels. Our results, alongside those of recent observational studies, strongly suggest that maintaining high α‐diversity in plant communities is important for conserving multiple components of arthropod diversity. As arthropods carry out a range of essential ecosystem functions, such as pollination and natural pest‐control, our findings provide crucial insight for effective planning of human‐dominated landscapes to maximize both ecological and economic benefits in grassland systems.
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Ecological network structure in response to community assembly processes over evolutionary time
Abstract The dynamic structure of ecological communities results from interactions among taxa that change with shifts in species composition in space and time. However, our ability to study the interplay of ecological and evolutionary processes on community assembly remains relatively unexplored due to the difficulty of measuring community structure over long temporal scales. Here, we made use of a geological chronosequence across the Hawaiian Islands, representing 50 years to 4.15 million years of ecosystem development, to sample 11 communities of arthropods and their associated plant taxa using semiquantitative DNA metabarcoding. We then examined how ecological communities changed with community age by calculating quantitative network statistics for bipartite networks of arthropod–plant associations. The average number of interactions per species (linkage density), ratio of plant to arthropod species (vulnerability) and uniformity of energy flow (interaction evenness) increased significantly in concert with community age. The index of specialization has a curvilinear relationship with community age. Our analyses suggest that younger communities are characterized by fewer but stronger interactions, while biotic associations become more even and diverse as communities mature. These shifts in structure became especially prominent on East Maui (~0.5 million years old) and older volcanos, after enough time had elapsed for adaptation and specialization to act on populations in situ. Such natural progression of specialization during community assembly is probably impeded by the rapid infiltration of non‐native species, with special risk to younger or more recently disturbed communities that are composed of fewer specialized relationships.
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- Award ID(s):
- 1927510
- PAR ID:
- 10493338
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Molecular Ecology
- Volume:
- 32
- Issue:
- 23
- ISSN:
- 0962-1083
- Page Range / eLocation ID:
- 6489 to 6506
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1111/mec.16873
