Evolutionary lability in floral ontogeny affects pollination biology in Trimezieae

Abstract

There is little direct evidence linking floral development and pollination biology in plants. We characterize both aspects in plain and ornamented flowers of Trimezieae (Iridaceae) to investigate how changes in floral ontogeny may affect their interactions with pollinators through time. METHODS:We examined floral ontogeny in 11 species and documented pollination biology in five species displaying a wide range of floral morphologies. We coded and reconstructed ancestral states of flower types over the tribal phylogeny to estimate the frequency of transition between different floral types.RESULTS: All Trimezieae flowers are similar in early floral development, but ornamented flowers have additional ontogenetic steps compared with plain flowers, indicating heterochrony. Ornamented flowers have a hinge pollination mechanism (newly described here) and attract more pollinator guilds, while plain flowers offer less variety of resources for a shorter time. Although the ornamented condition is plesiomorphic in this clade, shifts to plain flowers have occurred frequently and abruptly during the past 5 million years, with some subsequent reversals.CONCLUSIONS: Heterochrony has resulted in labile morphological changes during flower evolution in Trimezieae. Counterintuitively, species with plain flowers, which are endemic to the campo rupestre, are derived within the tribe and show a higher specialization than the ornamented species, with the former being visited by pollen-collecting bees only.

A trait‐based approach to determining principles of plant biogeography

“…One example is the recent focus on rates, that is, the number of evolutionary or biogeographical events happening in a given unit of time. Parametric measurements of rates have opened the possibility to explore questions related to the role of the environment on trait lability (e.g., Lovo et al, 2021) and the role of traits on niche conservatism and niche evolution (e.g., Smith and Beaulieu, 2009;López-Jurado et al, 2019;Qiu et al, 2019;Baniaga et al, 2020;Vasconcelos et al, 2023) rather than merely testing for support of a trait-environment correlation. Previously established generalities are also challenged when old hypotheses are confronted with new data that often come from poorly studied groups and areas (e.g., Vasconcelos et al, 2019Vasconcelos et al, , 2020.…”

Discovering the rules of plant biogeography using a trait-based approach

“…Measuring rates have opened the possibility to explore questions related to the role of the environment on trait lability (e.g. Lovo et al, 2021) and the role of traits on niche conservatism and niche evolution (e.g. Smith & Beaulieu, 2009;López-Jurado et al, 2019;Qiu et al, 2019;Baniaga et al, 2020;, rather than merely testing if support for a trait-environment correlation exists or not.…”