Land use and pollinator dependency drives global patterns of pollen limitation in the Anthropocene

Abstract

Land use change, by disrupting the co-evolved interactions between plants and their pollinators, could be causing plant reproduction to be limited by pollen supply. Using a phylogenetically controlled meta-analysis on over 2200 experimental studies and more than 1200 wild plants, we ask if land use intensification is causing plant reproduction to be pollen limited at global scales. Here we report that plants reliant on pollinators in urban settings are more pollen limited than similarly pollinator-reliant plants in other landscapes. Plants functionally specialized on bee pollinators are more pollen limited in natural than managed vegetation, but the reverse is true for plants pollinated exclusively by a non-bee functional group or those pollinated by multiple functional groups. Plants ecologically specialized on a single pollinator taxon were extremely pollen limited across land use types. These results suggest that while urbanization intensifies pollen limitation, ecologically and functionally specialized plants are at risk of pollen limitation across land use categories.

Pollinator dependence but no pollen limitation for eight plants occurring north of the Arctic Circle

“…Previous findings show that land use changes such as agricultural intensification, habitat fragmentation, and urbanization affect pollination service negatively, which might in turn cause pollen limitation in plants (Aguilar et al., 2006; Cunningham, 2000; Knight et al., 2018). A recent meta‐analysis shows that globally, plants in urban habitats are nearly twice as pollen limited as plants that occur in natural environments (Bennett et al., 2020). At our site, there have been little urbanization and agricultural activities, hence limited habitat fragmentation and pesticide use.…”

“…Plant mating systems such as autogamy (self‐fertilization) are known to buffer plant species from pollen limitation (Knight et al., 2005). Autogamous plants that are able to fully reproduce even in the absence of visits from animal pollinators are less prone to pollen limitation than plants with outcrossing mating systems (Bennett et al., 2020; Knight et al., 2005). The distributional pattern of autogamous plant mating systems across the globe is likely in response to low pollinator abundances or effectiveness of pollinators at some locations (Grossenbacher et al., 2015; Moeller et al., 2017; Ollerton et al., 2011).…”

Fragmentary Blue: Resolving the Rarity Paradox in Flower Colors

“… Schemske and Bierzychudek (2001) found a similar effect in Linanthus parryae , in that blue morphs produced more seeds than white morphs in years of low spring precipitation, possibly linked to bee preference. Since important pollinators like bees prefer blue hues, this suggests that in more stressful environments, selection might favor blue floral colors if possible, to provide resilience in the face of resource restrictions as to help attract presumably scarcer bee pollinators, as pollinator limitation is a major factor in plant reproductive success ( Burd, 1994 ; Bennett et al, 2020 ; Giejsztowt et al, 2020 ). However, few studies have considered pollinator perception in such analyses, and below we attempt to synthesize available evidence to bridge the potentially contributing abiotic and biotic factors that might influence flower coloration.…”

SNP Markers Reveal Relationships between Fruit Paternity, Fruit Quality and Distance from a Cross-pollen Source in Persea Americana Orchards

“…Pollination is essential for plant reproduction in both natural and agricultural ecosystems [1][2][3] . However, plant reproduction is increasingly limited by the quality or quantity of pollen deposited on the stigmas of owers 4,5 . Roughly 50% of plant species rely on or bene t from cross-pollination for successful reproduction 6,7 .…”

“…cross-pollination in almonds increases the oleic to linoleic acid ratio, which has been linked to their cardio-protective effects 17,19 . For most crops, we do not understand to what extent self-v. cross-pollination contribute to the crop at harvest despite plant reproduction being increasingly pollen limited 4,5 . We also do not know how self-v. cross-pollination affect crop quality parameters such as fruit size or nutritional quality.…”