Does Altering Local Water Availability for an Invasive Plant (Raphanus raphanistrum) Affect Floral Morphology and Reproductive Potential?

Abstract

Abiotic environmental variation can have dramatic effects on plant floral morphology and nectar or pollen rewards. In response, pollinators may change their foraging behavior and distribution and if pollinators change their foraging behavior or distribution, this could have dramatic effects on the reproductive success of plant populations. To start tackling this problem, we measured the response of floral morphology (corolla diameter, stamen length, and ovule number) of Raphanus raphanistrum to experimental manipulations of field soil moisture. As soil moisture increased, corolla diameter and anther length grew. We expect these changes to provide more visitation rewards for insects in moist conditions. Therefore, water availability influences growth and development of flowers, and may have dramatic effects on insect community dynamics. KEYWORDS: Floral Rewards, Climate, Rain-out Shelters, Flower Morphology, Raphanus raphanistrum, Brassicaceae

Germination rates of weedy radish populations (Raphanus spp.) altered by crop‐wild hybridisation, not human‐mediated changes to soil moisture

“…Despite evidence to suggest soil moisture plays a significant role in Raphanus seed development and fecundity Pirimova et al, 2015), we found surprisingly little effect of experimental watering treatment on seedbank dynamics. Importantly, hybrid populations exhibited germination rates more than double that of wild populations and 58% lower rate of dormancy compared with rates in wild populations (Table 1, Fig.…”

“…As in Pirimova et al . (), we transplanted cultivated and wild seedlings into 40 plots (F 0 ) (nine cultivated and nine wild seedlings per plot) at Waterman Farm during spring 2010. We planted seedlings in one of four watering treatment plots in a randomised complete block design with one plot per treatment, per block, making five blocks.…”

The Effect of Altered Soil Moisture on Hybridization Rate in a Crop-Wild System (Raphanus spp.)

“…Similarly, hybridization can occur only when foraging pollinators move between species. Furthermore, in an earlier study we have documented that increased water availability increased corolla diameter and potentially floral attractiveness [46]. We hypothesized that pollinator movements would correlate with actual hybridization events and thus rates of hybridization.…”

“…Our recent work has documented that R . raphanistrum corolla diameter and flower production decreases with decreasing soil moisture [45, 46]. Thus, shifts in hybridization rates may be a consequence of a series of plant responses to local environmental conditions.…”

Growth and fecundity of colonizing hybrid Raphanus populations are environmentally dependent

“…We wanted to determine whether the relative success of hybrids during invasion can be driven by both genetic and environmental variation in the habitat and ecological context of populations. As a hypothetical scenario, variation in water availability may alter plant size and/or the number of flowers produced by a plant, hence affecting the amounts of ovules and pollen produced (Conner et al, 1996a,b; Campbell et al, 2015; Pirimova et al, 2015; Younginger et al, 2017), and/or the number or size of seeds produced (e.g., Humara et al, 2002). Differences in pollen and seed production are known to drive differences in short‐term gene flow among populations (Loveless and Hamrick, 1984; Campbell, 1985; Brunet and Sweet, 2006).…”