Evolution of Bird and Insect Flower Traits in Fritillaria L. (Liliaceae)

Abstract

Pollinators are often perceived as a primary selective agent influencing flower traits such as colour, size, and nectar properties. The genus Fritillaria L. (Liliaceae), comprising approximately 150 species, is described as generally insect pollinated. However, there are at least three exceptions: two hummingbird-pollinated North American species and one passerine-pollinated Asian species. Despite this variation in pollination, little is known about flower traits that may accompany this shift in fritillaries. In this study, we aimed to assess the attractiveness of the floral traits for (new) pollinators and track the evolution of flowers traits in the context of a shift in the principal pollinator. Therefore, we studied 14 flower traits related to the pollination in 60 Fritillaria species and traced the evolutionary trajectory of these traits. We used a phylogenetic tree of the genus, based on five DNA markers (matK, rpl16, and rbcL, 18S, and ITS) to reconstruct the ancestral state of studied flower traits. The results show that in bird-pollinated species several new traits evolved. For example, flower colouration, nectar sugar, and amino acid concentration and composition fulfil the criteria of ornithophilous flowers, although flower traits do not exclude insect pollinators in bird-pollinated fritillaries. Interestingly, we recorded potential reversals from bird to insect pollination. Our analysis, showing a broad study of flower traits among closely related species in the context of pollinator shift, serves as a starting point for future work exploring the genetic and physiological mechanisms controlling flower traits in the genus Fritillaria.

Phylogenetical Position versus Pollination Syndromes: Floral Trichomes of Central American and Mexican Pinguicula

“…For example, red flowers attract butterflies, night-scented flowers attract moths, long-spurred flowers attract longtongued flies, the lack of spur in flowers attracts bees or wasps, and deceptive flowers attract carpenter bees. More recently published studies [74,75] revealed the appearance of some new floral characters within the Fritillaria genus related to floral morphology and reward, which led to shifts of principal pollinators. For instance, newly derived red and orange flowers in F. recurve, F. gentneri, and F. imperialis, as well as the alteration in their sugar and amino-acid content in nectar, have led to a pollinator shift for these species from insects to birds.…”

“…Examples of such adaptations to a new particular group of pollinators in far-related taxa have also been observed in Fritillaria genus, where species pollinated mainly by insects include twice-evolved ornithophily syndrome for F. recurve, F. gentneri from the Liliorhiza subgenus (pollinated by hummingbirds), and F. imperialis from the Petilium subgenus (pollinated by passerine birds). Interestingly, reversal shifts of a pollinator from ornithophily to myophily were also present [75]. Another excellent example of the diversification of pollination strategies within a single genus is presented by Disa genus, in which a monophyletic group of 27 studied taxa revealed multiple independent radial evolutions of various pollination syndromes [73].…”

Limited-Distance Pollen Dispersal and Low Paternal Diversity in a Bird-Pollinated Self-Incompatible Tree

“…Remarkably, generalist passerines have been demonstrated as the most effective pollinators for winter flowering plants in regions where sunbirds are absent, especially in dry seasons and in the islands (Chen et al, 2019). These include species such as Fritillaria imperialis (Roguz et al, 2021), Firmiana spp. (Huang et al, 2018), Rhodoleia spp.…”