No evolutionary change in the mating system of Solanum rostratum (Solanaceae) during its invasion in China

Abstract

The mating system of flowering plants plays a key role during the process of invasion. Evolution from outcrossing to selfing can allow rapid regeneration of a population after long-distance dispersal by providing reproductive assurance. Solanum rostratum is a self-compatible annual herb that exhibits a high level of outcrossing in its native populations. However, the mating system of invasive populations of S. rostratum has never been assessed. Here, we investigated the mating system based on 11 microsatellite loci and explored ecological factors that may influence the outcrossing rate among 10 invasive populations of S. rostratum in China. We found that the mean outcrossing rate was 0.69 ± 0.12 (range 0.49 to 0.83) with multiple paternity within progeny arrays (average effective number of sires = 7.86), which suggests a mixed mating system dominated by outcrossing. Combined with the uniformly high outcrossing rate (0.70 ± 0.03) previously reported in its native range, these results indicate that there has been no evolutionary shift in mating system during the invasion in China by S. rostratum. There were no relationships between outcrossing and population size, population density, altitude, latitude or longitude. Furthermore, high outcrossing of S. rostratum in China may be facilitated by enantiostyly and heteranthery.

Phenotypic plasticity and exotic plant invasions: Effects of soil nutrients, species nutrient requirements, and types of traits

“…Consistent with our hypothesis, S. rostratum with low‐nutrient requirements (Feng, 2020; Juan et al, 2013; Zhang et al, 2017; Zhao et al, 2013) showed lower growth plasticity than its related native species S. nigrum under both high and low soil nutrient environments. The lower growth plasticity of the invasive relative to the native species reduced its growth disadvantage when decreasing soil nutrients, contributing to its invasiveness under low (but not high) nutrient environment.…”

“…Consistent with our hypothesis, S. rostratum with low-nutrient requirements (Feng, 2020;Juan et al, 2013;Zhang et al, 2017;Zhao et al, 2013) showed lower growth plasticity than its related native promoting its invasion. Similarly, the marginally (P = 0.058) lower growth plasticity of the invasive species E. canadensis may also contribute to its invasiveness under low soil nutrient environment.…”

“…All these species can be found in disturbed habitats such as roadsides, railways, riversides, or abandoned fields. However, Solanum rostratum and Erigeron canadensis usually invade nutrient‐limited habitats such as sandy soil, having low‐nutrient requirements (Đurđević et al, 2015; Juan et al, 2013; Thébaud et al, 1996; Zhang et al, 2017; Zhao et al, 2013). Bidens frondosa , Xanthium strumarium , and Ambrosia trifida generally invade nutrient‐rich habitats with regular nutrient addition, such as farmlands and wetlands, having high‐nutrient requirements (Danuso et al, 2012; Dong et al, 2020; Follak et al, 2013; Iqbal et al, 2020; Ronzhina, 2017).…”

“…T A B L E 1 The five pairs of phylogenetically related invasive and native species used in this study . (2013);Zhang et al (2017);Zhao et al (2013) …”

Habitat effects on reproductive phenotype, pollinator behavior, fecundity, and mating outcomes of a bumble bee–pollinated herb

“…Most obviously, pollinators often facilitate self‐pollination within (facilitated autogamy) or among (geitonogamy) a plant's flowers (Harder and Barrett, 1995; Eckert, 2000; Owen et al, 2007), the incidence of which can vary among populations (Christopher et al, 2021). In addition, population differences in outcross‐mate diversity (Sun and Ritland, 1998; Yates et al, 2007; Zhang et al, 2017) must arise from variation in processes specifically involved in cross‐pollination.…”