Global distribution and evolutionary transitions of angiosperm sexual systems

Abstract

Angiosperm sexual systems are fundamental to the evolution and distribution of plant diversity, yet spatiotemporal patterns in angiosperm sexual systems and their drivers remain poorly known. Using data on sexual systems and distributions of 68453 angiosperm species, we present the first global maps of sexual system frequencies and evaluate sexual system evolution during the Cenozoic. Frequencies of dioecy and monoecy increase with latitude, while hermaphrodites are more frequent in warm and arid regions. Transitions to dioecy from other states were higher than to hermaphroditism, but transitions away from dioecy increased since the Cenozoic, suggesting that dioecy is not an evolutionary end point. Transitions between hermaphroditism and dioecy increased, while transitions to monoecy decreased with paleo‐temperature when paleo‐temperature >0℃. Our study demonstrates the biogeography of angiosperm sexual systems from a macroecological perspective, and enhances our understanding of plant diversity patterns and their response to climate change.

Seed dormancy in space and time: global distribution, paleoclimatic and present climatic drivers, and evolutionary adaptations

“…Because actual sampling effects make it almost impossible to include all species in an area, uneven spatial sample sizes often lead to over or underestimates of the effect size and are described as ‘sampling bias’ (Kramer‐Schadt et al ., 2013). Thus, we explored the relationship between proportion of D and proportion of species sampled to determine spatial sampling biases (Wang et al ., 2021), using beta‐inflated regression and a modified t ‐test. Sampling proportion was calculated as the ratio between SR obtained by sampling and total SR within each grid cell; total SR was estimated based on Kreft & Jetz (2007).…”

“…Furthermore, owing to the low sampling fraction of our data compared with the total number of accepted species of seed plants (12 743/296 462; Christenhusz & Byng, 2016), we assessed the reliability of transition estimates given the large fraction of missing taxa following previous studies (Igea & Tanentzap, 2020; Wang et al ., 2021). We randomly sampled 25% of the species in our full dataset ( n = 3186) in detail 100 times and confirmed the proportion of D status in each subsample (79% for D and 21% for ND).…”

“…To explore the potential effect of paleotemperature dynamics on the transition of D states (D vs ND) along evolutionary time for all species and the two life-forms, we regressed the temporal changes of the frequency of each D state and transitions rate between D and ND against paleotemperature during the Cenozoic (65-0 million years ago (Ma)) using beta-inflated regressions. The paleotemperature data were derived from Zachos et al (2001), and they have been widely used as a proxy of long-term global temperature change in biogeographical and paleoclimate studies (Condamine et al, 2013;Schubert et al, 2019;Ding et al, 2020;Wang et al, 2021). The average value for each 1 Ma time-slice was calculated.…”

“…Many studies have explored the relationships between seed D and current environmental cues – for example, temperature, precipitation, and seasonality (Baskin & Baskin, 2014; Rubio de Casas et al ., 2017) – but few have been concerned with the influence of paleoenvironments on seed D. Long‐term paleoenvironment changes have shaped not only species diversification (Ding et al ., 2020) but also floral assembly (Chen et al ., 2018) and trait evolution (Condamine et al ., 2013; Wang et al ., 2021; Zhang et al ., 2021a). By reviewing the paleoclimate dynamics and fossils, Baskin & Baskin (2014) provided some speculations about development of seed D; for example, paleotemperature shifts causing environmental stress (e.g.…”

Development and Evolution of Unisexual Flowers: A Review

“…Lability in this trait is also not seldom, as the sexual system of many plant taxa varies with the environmental conditions preceding the flowering season [35][36][37][38]. The ecological and genetic significance of flower functional unisexuality (e.g., avoidance of inbreeding depression (Box 2)) was addressed in several pivotal studies ( [3] and references therein, [39,40]). Terminology relative to flower sexual systems is complex [41], and we provided definitions of a selection of terms in Box 2.…”