Inbreeding in Solanum carolinense alters floral attractants and rewards and adversely affects pollinator visitation

Abstract

Inbreeding depression is well documented in flowering plants and adversely affects a wide range of fitness-related traits. Recent work has begun to explore the effects of inbreeding on ecological interactions among plants and other organisms, including insect herbivores and pathogens. However, the effects of inbreeding on floral traits, floral scents, and pollinator visitation are less well studied. METHODS: Using inbred and outbred maternal families of horsenettle (Solanum carolinense, Solanaceae), we examined the effects of inbreeding on traits associated with pollinator attraction and floral rewards. Specifically, we measured corolla size, counted pollen grains per flower, and analyzed floral volatile emissions via gas chromatography and mass spectrometry. We also examined pollinator visitation to experimental arrays of flowering inbred and outbred plants under field conditions. RESULTS: Compared to those of outbred plants, flowers of inbred plants exhibited reduced corolla size and pollen production, as well as significantly reduced emission of the two most abundant volatile compounds in the floral blend. Furthermore, bumblebees-the main pollinators of horsenettle-discriminated against inbred flowers in the field: bees were more likely to make initial visits to flowers on outbred plants, visited outbred flowers more often overall, and spent more time on outbred flowers. CONCLUSIONS: These results show that inbreeding can (1) alter floral traits that are known to mediate pollinator attraction; (2) reduce the production of floral rewards (pollen is the sole reward in horsenettle); and (3) adversely affect pollinator visitation under field conditions.

Inbreeding in a dioecious plant has sex- and population origin-specific effects on its interactions with pollinators

“…In summary, our research on S. latifolia suggests that in addition to inbreeding disrupting interactions with herbivores by changing plant leaf chemistry (Schrieber et al, 2018) it affects plant interactions with pollinators by altering flower chemistry. Our observations are in line with studies on other plant species (Ivey and Carr, 2005;Kariyat et al, 2012Kariyat et al, , 2021 and highlight that inbreeding has the potential to reset the equilibrium of species interactions by altering functional traits that have developed in a long history of co-evolution. These threats to antagonistic and symbiotic plant-insect interactions may mutually magnify in reducing plant individual fitness and altering the dynamics of natural plant populations under global change.…”

“…The chemodiversity and abundance of floral VOC involved in communication with H. bicruris moths was reduced in a sex- and origin-specific manner in inbred relative to outbred S. latifolia ( Figure 2e–g ), while the full floral scent profile exhibited no differences among inbreds and outbreds ( Figure 2—figure supplement 2 ). So far, lower emissions of floral VOC in inbreds have been reported for only few plant species pollinated by diurnal generalists ( Ferrari et al, 2006 ; Haber et al, 2019 ; Kariyat et al, 2021 ). Our study revealed such effects for plants pollinated by specialist moths that use scent as a major cue for plant location ( Riffell and Alarcón, 2013 ).…”

“…a single study. Kariyat et al (2021) demonstrated that inbred Solanum carolinense L. display reduced flower size, pollen and scent production and receive fewer visits from diurnal generalists. It is necessary to broaden such integrated methodological approaches to other plant-pollinator systems (e.g., nocturnal specialist pollinators) and further floral traits (i.e., flower colour).…”

“…Although in a few cases inbreeding has been shown to alter single floral traits ( Ivey and Carr, 2005 ; Ferrari et al, 2006 ; Haber et al, 2019 ), insight into more syndrome-wide effects is restricted to a single study. Kariyat et al, 2021 demonstrated that inbred Solanum carolinense L. display reduced flower size, pollen and scent production, and receive fewer visits from diurnal generalists. It is necessary to broaden such integrated methodological approaches to other plant-pollinator systems (e.g., nocturnal specialist pollinators) and further floral traits (e.g., flower colour).…”

Examining the Role of Buzzing Time and Acoustics on Pollen Extraction of Solanum elaeagnifolium

“…For instance, Solanum-type flowers have evolved across Primilaceae, Gesneriaceae, and Ericaceae, in addition to Solanaceae with typical characteristics of buzz-pollinated species. These include the presence of poricidal anthers and the lack of nectar or other pollen rewards, which dispense pollen only to the authorized buzz pollinators [2,[5][6][7]. Flowers from most of the Solanum spp.…”