Plant phenotypic plasticity changes pollinator‐mediated selection

Abstract

Many organisms change their phenotype in response to the environment, a phenomenon called phenotypic plasticity. Although plasticity can dramatically change the phenotype of an organism, we hardly understand how this can affect biotic interactions and the resulting phenotypic selection. Here, we use fast cycling Brassica rapa plants in an experiment in the greenhouse to study the link between plasticity and selection. We detected strong plasticity in morphology, nectar, and floral scent in response to different soil types and aphid herbivory. We found positive selection on nectar and morphological traits in hand‐ and bumblebee‐pollinated plants. Bumblebee‐mediated selection on a principal component representing plant height, flower number, and flowering time (mPC3) differed depending on soil type and herbivory. For plants growing in richer soil, selection was stronger in the absence of herbivores, whereas for plants growing in poorer soil selection was stronger with herbivory. We showed that bumblebees visited tall plants with many flowers overproportionally in plants in poor soil with herbivory (i.e., when tall plants were rare), thus causing stronger positive selection on this trait combination. We suggest that with strong plasticity under most stressful conditions, pollinator‐mediated selection may promote adaptation to local environmental factors given sufficient heritability of the traits under selection.

Variation in scent amount but not in composition correlates with pollinator visits within populations of deceptive Arum maculatum L. (Araceae)

“…Overall, this raises the possibility that variation of relative scent composition in DAO ( Figure 1F ) could be subject to different selection pressures by fly pollinators (see also Chartier et al., 2013 ; Szenteczki et al., 2021 ; Gfrerer et al., 2022 ). However, we caution that other than pollinator-related factors can maintain variation in floral scent and affect the reproductive success of plant species, such as resource limitation ( Albre et al., 2003 ), herbivory ( Knauer and Schiestl, 2017 ; Ramos and Schiestl, 2019 ; Rusman et al., 2019 ), and potential seasonal variation in floral scent ( Dorey and Schiestl, 2022 ).…”

Chemistry, biosynthesis and biology of floral volatiles: roles in pollination and other functions

“…Herbivory by aphids on this plant species also affected floral scent emissions. 177 The amounts of 88 , 111 , methyl benzoate ( 100 ) and methyl salicylate ( 125 ) were decreased, whereas 1-butene-4-isothiocyanate ( 137 ) and ( Z )-3-hexenyl acetate ( 110 ) increased. For B. rapa , it was also shown that herbivory not only has direct effects on floral scent emissions, but also influences the evolution of floral scents.…”

“…[276][277][278][279][280][281][282] Here a few examples for studies that successfully identied compounds that elicit behavioral responses in mosquitoes are given. Otienoburu et al 283 analysed oral scents in the common milkweed Asclepias syriaca, which is visited by the northern house mosquito, Culex pipiens, and demonstrated that a blend of benzaldehyde ( 88), phenylacetaldehyde (83), and (E)-2-nonenal (177) is key in the attraction of the mosquitoes to the owers. Similarly, acetophenone (135) from sweet alyssum (Lobularia maritima) owers successfully attracted the yellow fever mosquito, Aedes aegypti.…”

“…174 A very recent study on Brassica rapa did not find an effect of soil type (limestone versus tuff) on floral scent emissions. 177…”

“…reviewed by 137,200–204 Meanwhile, there are some studies available that link herbivory on leaves and flowers to floral chemistry and pollinator attraction. They have found that herbivory/florivory often, but not always, 169,205 has effects on floral scent emissions, 177,206 and that different herbivores can have different effects on floral scent emissions. 207–209 Further, herbivory-induced changes in scent emissions often translate to differences in flower visitor behaviors 169,171,203,207,210–213 and plant reproduction, 214 but see 211 and herbivores exert selective pressures on plants and affect the evolution of floral scents.…”