How Have Advances in Comparative Floral Development Influenced Our Understanding of Floral Evolution?

Abstract

Editor: Patrick S. HerendeenEvolutionary developmental biology has come to prominence in the past two decades, in both the plant kingdom and the animal kingdom, particularly following the description of homeotic genes linked to key morphological transitions. A primary goal of evolutionary developmental biology ("evo-devo") is to define how developmental programs are modified to generate novel or labile morphologies. This requires an understanding of the molecular genetic basis of these programs and of the evolutionary changes they have undergone. The past decade has seen the establishment of a common language and common standards, and these changes have greatly improved the integration of evo-devo. Recently, a more comparative approach has been added to mechanistic developmental biology. In this review we attempt to show how, by using this "next-generation evo-devo" approach, insights into both developmental biology and evolutionary biology can be gained. Although the concepts we discuss are more broadly applicable, we have focused our examples on traits of the angiosperm flower, a structure that has undergone enormous morphological and developmental evolution since its relatively recent appearance in the fossil record.

Introgression and repeated co-option facilitated the recurrent emergence of C4photosynthesis among close relatives

“…However, the power of character modeling remains inherently limited by the small number of informative characters. Decomposing the phenotype into its components can solve this problem, especially when the underlying genetic determinism is considered (Oliver et al 2012;Niemiller et al 2013;Glover et al 2015;Meier et al 2017), and good mechanistic models exist for the evolution of DNA sequences (Liberles et al 2013). Violation of model assumptions can still mislead the conclusions, but the multiplication of sources of information, coupled with the possibility to track the history of specific genes independently of the species tree, limits the risks of systematic errors.…”

Temporal, but not spatial, changes in expression patterns of petal identity genes are associated with loss of papillate conical cells and the shift to bird pollination in Macaronesian Lotus (Leguminosae)

“…; Glover et al . ). It is possible that the loss of papillate conical cells in the bird‐pollinated Lotus will contribute to their lack of attractiveness to bees.…”

“…The transition in pollination syndromes implied the loss of conical cells in the dorsal petal and a re-location to a specific site in the lateral petal (Ojeda et al 2012a,b). Papillate conical cells provide an important cue for bees by providing distinctive optical and tactile characteristics (Kay et al 1981;Kevan & Lane 1985;Noda et al 1994;Gorton & Vogelmann 1996;Glover & Martin 1998, 2002Comba et al 2000;Martin & Glover 2007;Ojeda et al 2009;Whitney et al 2009;Glover et al 2015). It is possible that the loss of papillate conical cells in the bird-pollinated Lotus will contribute to their lack of attractiveness to bees.…”

The evolution of floral ontogenetic allometry in the Andean genus Caiophora (Loasaceae, subfam. Loasoideae)

“…Flower morphology underwent enormous evolutionary changes, adapting to a wide arrange of environmental conditions, including different mating and pollination scenarios (Barrett, ; Fenster, Armbruster, Wilson, Dudash, & Thomson, ; Strauss & Whittall, ). Duplication, loss or merging of floral structures, homeotic changes of flower organs, and changes in flower symmetry are among the mechanisms that enabled floral structure to evolve (Becker, Alix, & Damerval, ; Endress, ; Glover, Airoldi, Brockington, Fernández‐Mazuecos, & Martínez‐Pérez, ). Even among taxa that share the same floral bauplan, evolutionary changes in the sizes, shapes, and arrangement of floral structures produced extensive variation in floral morphology (Gardner et al, ; Gómez, Torices, Lorite, Klingenberg, & Perfectti, ; McCarthy et al, ).…”