Global analysis of floral longevity reveals latitudinal gradients and biotic and abiotic correlates

Abstract

The length of time a flower remains open and functionalfloral longevitygoverns important reproductive processes influencing pollination and mating and varies considerably among angiosperm species. However, little is known about large-scale biogeographic patterns and the correlates of floral longevity.Using published data on floral longevity from 818 angiosperm species in 134 families and 472 locations world-wide, we present the first global quantification of the latitudinal pattern of floral longevity and the relationships between floral longevity and a range of biotic and abiotic factors.Floral longevity exhibited a significant phylogenetic signal and was longer at higher latitudes in both northern and southern hemispheres, even after accounting for elevation. This latitudinal variation was associated with several biotic and abiotic variables. The mean temperature of the flowering season had the highest predictive power for floral longevity, followed by pollen number per flower. Surprisingly, compatibility status, flower size, pollination mode, and growth form had no significant effects on flower longevity.Our results suggest that physiological processes associated with floral maintenance play a key role in explaining latitudinal variation in floral longevity across global ecosystems, with potential implications for floral longevity under global climate change and species distributions.

Canopy height, rather than neighborhood effects, shapes leaf herbivory in a tropical rainforest

“…Model residuals were checked for spatial autocorrelation using Moran's I with the spdep R package (Ehbrecht et al, 2021). To compare the relative contribution of different variables to the herbivory variation, we compared the SD caused by each fixed effect and the finite population SD caused by phylogenetic history (Gelman, 2005; Ratcliffe et al, 2017; Song et al, 2022). Considering that the 10‐m radius around each tree might be too large and dilute the effects of neighbors, we conducted additional analyses by reducing the radius to 5 m to evaluate possible scale dependency of the neighborhood effects on herbivory.…”

“…Canopy height could also have effects on leaf size, SLA, and the species' richness/abundance of neighbors, resulting in indirect effects on herbivory. We constructed a phylogenetic structural equation model (SEM) to explore the direct and indirect effects of canopy height on herbivory (Song et al, 2022). In this model, a phylogenetic correlation matrix was also included with the species name as the random effect (Song et al, 2022).…”

Flowers are leakier than leaves but cheaper to build

“…Flowers are critical to reproduction in angiosperms and have been credited with promoting diversification and the rapid spread of flowering plants globally (Sanderson & Donoghue, 1994;Crepet & Niklas, 2009;Leslie et al, 2021). Although they are typically short-lived, flowers require resources, such as carbon, water, and nutrients, for their production and maintenance (Reekie & Bazzaz, 1987a,b;Ashman & Schoen, 1994;Song et al, 2022). Water, in particular, is needed throughout development and anthesis for a variety of functions, including driving growth and expansion, keeping flowers turgid and on display for pollinators, providing rewards such as nectar, and for regulating temperature (Bazzaz et al, 1987;Galen et al, 1999;Patiño & Grace, 2002;Chapotin et al, 2003;De la Barrera & Nobel, 2004;Roddy & Dawson, 2012;Roddy, 2019;Treado et al, 2022).…”

“…Longer-lived flowers may incur higher carbon costs because they may need to withstand attack by floral enemies (Ashman, 1994;Roddy et al, 2021;Boaventura et al, 2022;Song et al, 2022). How biomass costs of flowers are related to other resources can be variable and contextdependent (Bazzaz et al, 1987;Reekie & Bazzaz, 1987b;Roddy et al, 2021), but the water and carbon costs may be coupled in important ways.…”

Complementary water and nutrient utilization of perianth structural units help maintain long floral lifespan inDendrobium

“…One strategy that orchids use to increase reproductive success is the prolongation of floral displays ( Ashman et al , 1994 ; van Doorn, 1997 ; Galen, 1999 ; Abdala-Roberts et al , 2007 ; Vega and Marques, 2015 ). However, prolonged floral longevity is costly ( Ashman et al , 1994 ; Galen, 1999 ), especially in environments characterized by limited supplies of water and nutrients, like the epiphytic environment inhabited by 70% orchid species ( Zotz and Hietz 2001 ; Laube and Zotz 2003 ; Arroyo et al , 2013 ; Jorgensen and Arathi, 2013 ; Song et al , 2022 ). Understanding the anatomical and physiological mechanisms that underlie the maintenance of long-lived flowers may provide insights into the ecological adaptation of orchids, and the production of new cultivars with long lifespan of flowers.…”