The role of fetid olfactory signals in the shift to saprophilous fly pollination in Jaborosa (Solanaceae)

Flower Diversification Across “Pollinator Climates”: Sensory Aspects of Corolla Color Evolution in the Florally Diverse South American Genus Jaborosa (Solanaceae)

“…Saprophilous flies use both olfactory and visual cues to find oviposition substrates ( Wall and Fisher, 2001 ; Chen et al, 2015 ). We previously demonstrated that floral scent, specifically sulfur-containing volatile compounds, plays an important role as an attractant of saprophilous flies to flowers of J. rotacea and J. laciniata in natural settings ( Moré et al, 2013 , 2019 ).…”

“…This asymmetry in pollinator distribution, which defines pollinator climate for Jaborosa , is highlighted by a simple experiment in which volatile sulfides typical of saprophilous fly pollinated J. laciniata were added to the large, white flowers of J. integrifolia in its lowland habitat during daytime. Within minutes of scent augmentation, calliphorid flies approached, landed upon, and attempted to feed from the sphingophilous flowers of J. integrifolia ( Moré et al, 2019 ). Thus, the putative direction of evolution in Figure 4 (e.g., from a sphingophilous ancestry) suggests a transition to fly pollination in colder, drier habitats devoid of hawkmoths, whereas saprophilous flies are present in all habitats occupied by Jaborosa species.…”

“…For the purpose of analysis, we classified the area now occupied by Jaborosa in three main environmental zones that are consistent with groups of widely recognized ecoregions in South America (see Olson et al, 2001 and Supplementary Table 2 ): (1) humid lowland zone, (2) dry lowland and foothill zone, and (3) alpine and high latitude zone. These zones range in pollinator environment from hawkmoth-dominated to fly-dominated pollinator climates (see Arroyo et al, 1982 ; Elberling and Olesen, 1999 ; Devoto et al, 2005 ; Chacoff et al, 2012 ; Sazatornil et al, 2016 ; Moré et al, 2019 ). This classification is constrained by the relevant groups of pollinators for Jaborosa species and does not include Hymenoptera and vertebrates (bats, hummingbirds, and rodents) that are also important pollinators in the dry lowland and high altitude habitats of southern South America, respectively ( Strelin et al, 2017 ; Dellinger et al, 2019 ).…”

“…(Solanaceae) is endemic to southern South America and exhibits strong inter-specific variation in floral traits across geographic domains. Such variation ranges from night-blooming white fragrant flowers with very long corolla tubes (Vesprini and Galetto, 2000) that produce abundant nectar, to diurnal, dark pigmented, unpleasant smelling flowers with shallow corollas that produce little to no nectar (Moré et al, 2013(Moré et al, , 2019. Two utterly different pollination modes have been described associated with these extreme phenotypes: nectar-rewarding flowers pollinated by nocturnal hawkmoths and rewardless brood-site deceptive flowers pollinated by saprophilous flies, respectively.…”

Floral Scent Evolution in the Genus Jaborosa (Solanaceae): Influence of Ecological and Environmental Factors

“…Here, we asked whether Jaborosa species with different pollination modes differ predictably in floral scent profiles, taking into account the evolutionary and geoclimatic context of diversification across the genus. Our previous studies of Jaborosa have addressed functional aspects of floral scent in focal case studies [ 57 , 58 ], phylogenetic reconstruction [ 55 ] and broader genus-wide trends in flower color as perceived by pollinators [ 56 ]. Here, we have used an ecological niche modelling (ENM) approach to analyze which environmental variable(s) (e.g., latitude, elevation, temperature, and precipitation) have exerted the strongest influence on floral scent profiles across a broader sample (eight spp.)…”