Forest Maturity and Structural Complexity Drive Harvestman Functional Diversity in Atlantic Forest
A new study published on bioRxiv found that successional stage and structural complexity of Atlantic Forest patches in southeastern Brazil significantly shape the functional trait diversity of harvestmen (Opiliones). Researchers sampled 384 individuals across 14 morphospecies in forest patches at different stages of succession, finding that functional beta diversity was dominated by nestedness rather than species turnover — meaning less mature patches contained only subsets of the trait space found in mature forests. The results suggest that protecting structurally complex, mature Atlantic Forest is critical to preserving the full range of ecological strategies represented by harvestman communities.
Researchers investigated how forest succession influences both taxonomic and functional diversity of harvestmen in a remnant Atlantic Forest site in southeastern Brazil, a globally threatened biodiversity hotspot. Using standardized nocturnal active searches and leaf-litter sampling, they collected 384 individuals belonging to 14 morphospecies and quantified functional diversity from four morphological traits using Hill numbers at multiple diversity orders (q = 0, 1, and 2). A key finding was that functional diversity declined sharply as rarer species were down-weighted, indicating that uncommon species disproportionately contribute to the regional morphofunctional variation. Beta-diversity partitioning revealed that functional dissimilarity among sampling points was driven primarily by nestedness rather than turnover, meaning assemblages in structurally simpler or younger forest patches were not distinct communities but rather impoverished subsets of the trait space present in mature patches. Environmental models identified litter depth, vegetation structure, and forest-maturity gradients as significant predictors of functional diversity. Morphofunctional analyses distinguished compact, robust, and long-legged species groups with likely different ecological roles. The authors conclude that harvestmen are promising bioindicators for trait-based conservation and that maintaining mature, structurally complex Atlantic Forest patches is essential for preserving the full spectrum of harvestman functional strategies.
What's missing
As a preprint, this study has not yet undergone formal peer review, and its findings should be interpreted with caution. The authors do not report sample sizes per successional stage, making it difficult to assess whether sampling effort was balanced across forest types. Additionally, the use of morphospecies rather than formally described species may introduce taxonomic uncertainty that could affect functional trait assignments.
What different sources said
- bioRxivCenter
Forest maturity and functional nestedness shape harvestman trait diversity in the Atlantic Forest
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