Phenotypic plasticity guidesMoricandia arvensisdivergence and convergence across the Brassicaceae floral morphospace

Abstract

Many flowers exhibit phenotypic plasticity. By inducing the production of several phenotypes, plasticity may favour the rapid exploration of different regions of the floral morphospace. We investigated how plasticity drives Moricandia arvensis, a species displaying withinindividual floral polyphenism, across the floral morphospace of the entire Brassicaceae family.We compiled the multidimensional floral phenotype, the phylogenetic relationships, and the pollination niche of over 3000 species to construct a family-wide floral morphospace. We assessed the disparity between the two M. arvensis floral morphs (as the distance between the phenotypic spaces occupied by each morph) and compared it with the family-wide disparity. We measured floral divergence by comparing disparity with the most common ancestor, and estimated the convergence of each floral morph with other species belonging to the same pollination niches.Moricandia arvensis exhibits a plasticity-mediated floral disparity greater than that found between species, genera and tribes. The novel phenotype of M. arvensis moves outside the region occupied by its ancestors and relatives, crosses into a new region where it encounters a different pollination niche, and converges with distant Brassicaceae lineages.Our study suggests that phenotypic plasticity favours floral divergence and rapid appearance of convergent flowers, a process which facilitates the evolution of generalist pollination systems.

Plant phenotypic plasticity changes pollinator‐mediated selection

“…For example, abiotic stress can impose changes on plant-pollinator (Harrison 2000;Burkle and Runyon 2016;Powers et al 2022) as well as plant-herbivore interactions (Mattson and Haack 1987;Price 1991). In Moricandia arvensis (Brassicaceae), climatic factors elicit intraindividual flower plasticity with large, cross-shaped lilac flowers produced in spring and small, rounded white flowers in summer that differ in the pollinators they attract (Gomez et al 2022). Herbivore-induced defenses are known to alter pollinator behavior, for example, through changing flower signals and/or nectar chemistry, usually rendering flowers less attractive to pollinators (Lehtila and Strauss 1997;Adler et al 2006;Kessler et al 2011;Schiestl et al 2014;Rusman et al 2020; but see Poveda et al 2003;Cozzolino et al 2015;Goulnik et al 2020).…”

“…In Moricandia arvensis (Brassicaceae), climatic factors elicit intraindividual flower plasticity with large, cross‐shaped lilac flowers produced in spring and small, rounded white flowers in summer that differ in the pollinators they attract (Gomez et al. 2022). Herbivore‐induced defenses are known to alter pollinator behavior, for example, through changing flower signals and/or nectar chemistry, usually rendering flowers less attractive to pollinators (Lehtila and Strauss 1997; Adler et al.…”

Rapid evolution of a family‐diagnostic trait: artificial selection and correlated responses in wild radish,Raphanus raphanistrum

“…We are not aware of selection estimates on anther separation in species other than wild radish, so it is unclear how much this explanation holds across the family, but many Brassicaceae have generalized pollination similar to wild radish (fig. S2 in Gómez et al ., 2022). Stanleya pinnata has secondarily lost tetradynamy, which could have been caused by selection for its extreme anther exsertion (anthers far outside the corolla; Conner, 2006).…”

Scott Armbruster

“…At a larger scale, valuable insights into floral evolvability come from an exciting integrative study of plasticity and deep‐phylogenetic patterns of phenotypic disparity in Brassicaceae by Gómez et al . (2022). These and many other innovative, even revolutionary, papers show clearly that we live in truly interesting times scientifically!…”