Altitudinal, temporal and trophic partitioning of flower-visitors in Alpine communities

Abstract

The cross-pollination of most alpine plants depends on insects, whose altitudinal distribution is limited by temperature. However, although global warming is causing shifts in temporal and spatial species distribution, we are still largely unaware of how plant-pollinator interactions change with elevation and time along altitudinal gradients. This makes the detection of endangered interactions and species challenging. In this study, we aimed at providing such a reference, and tested if and how the major flower-visiting insect orders and families segregated by altitude, phenology and foraging preferences along an elevational gradient from 970 m to 2700 m in the Alps. Flies were the main potential pollinators from 1500 m, as bees and beetles decreased rapidly above that limit. Diptera, Coleoptera and Hymenoptera differed significantly in the angiosperm assemblages visited. Within Diptera, the predominant group, major families segregated by both phenology and foraging preferences along the gradient. Empidids, muscids and anthomyiids, whose role in pollination has never been investigated, dominated the upper part of the gradient. Our results thus suggest that flies and the peculiar plants they visit might be particularly at risk under global warming, and highlight the blatant lack of studies about critical components of these rich, yet fragile mountain ecosystems.

Temperature-driven changes of pollinator assemblage and activity of Megaleranthis saniculifolia (Ranunculaceae) at high altitudes on Mt. Sobaeksan, South Korea

“…3) may increase the fitness of M. saniculifolia. The fact that M. saniculifolia (Han et al 2010) and flies (Kearns 1992;Lefebvre et al 2018) are both vulnerable to high temperature and desiccation should be considered in the conservation of this rare endemic plant under warmer and less snowy climate. However, we still know little about how significantly the flies affect M. saniculifolia's reproductive success.…”

“…Such information helps infer possible changes in future pollinator assemblages and activity due to climate change (Hegland et al 2009). Recently, the global trend of rising temperatures has resulted in reduced pollinator abundance, which can threaten the survival of high-altitude plants that highly depend on them (Lefebvre et al 2018). Altitudinal scale investigation can be a good proxy for inferring the impact of temperature change on pollinator assemblage and activity as temperature varies with elevation (Hegland et al 2009).…”

Geographical distribution of dioecy and its ecological correlates based on fine‐scaled species distribution data from a subtropical island

“…Some studies reviewed the richness of terrestrial insect species along elevational gradients (Hodkinson, ). Most such studies, which were conducted at 0–2,000 m, revealed a decreasing pattern of insect richness with elevation (Hanski, , in Indonesia; Wolda, , in Panama; McCoy, , in the southeastern United States; Perillo, Neves, Antonini, & Martins, , in tropical Brazil), or discovered a pattern that peaks at mid‐elevations (Gagne, , in Hawaii; McCoy, , in the southeastern United States; Lefebvre, Villemant, Fontaine, & Daugeron, , in the southern Alps, France). Insects are the main pollinators of flowering plants in general, regardless of whether they are generalists or specialists (Jacquemyn et al, ), thus it is reasonable to suspect that our finding on the decline in dioecy may be partially correlated with the change of insect pollinators along the elevational gradient.…”

Elevational filtering and the evolution of planthoppers (Hemiptera, Fulgoromorpha) in Papua New Guinea

“…Machac, Janda and Dunn () studied phylogenetic patterns of ant species assemblages along an elevation gradient in three temperate montane systems, documenting contrasting patterns of overdispersion—suggesting competition—in ant communities at higher elevations, and clustering at lower elevations, suggesting environmental filtering likely driven by temperature in this case. Temperature is also one of the most important parameters segregating community assemblages in the temperate Alp Mountains for pollinating Diptera (Lefebvre et al., ) and for butterflies (Pellissier et al., ). In both cases, higher elevations entail lower temperatures that filter community assemblages, leading to the presence of closely related species.…”

“…Elevational gradients have been widely studied (Chatelain, Plant, Soulier‐Perkins & Daugeron, ; Lefebvre, Villemant, Fontaine & Daugeron, ; Lessard et al., ; Manel et al., ; McCain & Grytnes, ; Mouquet et al., ; Rahbek, , ; Sanders, Moss & Wagner, ), but incorporating phylogenetic information now allows to shed light on specific processes that shape the structure of communities along such gradients (Chazot et al., ; Graham & Fine, ; Graham, Parra, Rahbek & McGuire, ; Lessard et al., ; Manel et al., ; Pellissier et al., ). Indeed, over the last two decades, phylogenetic information has been increasingly incorporated into community ecology studies, either as a proxy for species’ ecological traits (ecophylogenetics, Webb, Ackerly, McPeek & Donoghue, ; Cavender‐Bares, Kozak, Fine & Kembel, ), to correct for non‐independence of co‐occurring species in the analyses of species’ traits (e.g., Losos et al., ) or to detect particular patterns, such as phylogenetically non‐random extinctions in communities driven by climate changes (Thuiller, Lavergne, Roquet, Boulangeat & Araujo, ).…”