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Dryad

Data from: Multiple metrics of trichome diversity support independent evolutionary hypotheses in blazingstars (Mentzelia: Loasaceae)

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Mar 18, 2025 version files 87.44 KB

Abstract

Trichomes are morphologically diverse and functionally important structures that vary within plant lineages in response to selection pressures across ecological gradients and evolutionary timescales. Classic hypotheses predict higher investment in trichomes in arid environments, at lower latitudes, and in long-lived species, as well as shifts in trichome production to reduce conflict between defense traits and mutualisms. However, tests of these hypotheses often neglect the rich diversity of trichome phenotypes and rely on aggregate metrics of trichome production, despite many plant species producing a variety of trichome morphologies across different organs. Here, we collected data on fine-scale patterns of trichome length, density, and type in 52 species of blazingstars (Mentzelia: Loasaceae) and tested whether individual metrics of trichome investment were consistent with existing adaptive hypotheses. Contrary to longstanding hypotheses, we found that Mentzelia species tend to display greater trichome investment in less arid environments and at higher latitudes. Sticky trichomes are significantly less common on the upper surface of the leaf, possibly reducing defense-pollination conflict. Species with larger petals (a proxy for reliance on insect pollinators) also shift investment away from insect-trapping hairs on the underside of the leaf. Examining trichomes types separately revealed that different morphologies show distinct responses to abiotic and biotic factors, demonstrating the need to consider multiple axes of diversity when testing adaptive hypotheses for complex traits.