Pollinator limitation on reproductive success in Iris tuberosa

Abstract

In this paper I measured the effect of varying pollinator visits on fruit production in order to understand pollination strategy in Iris tuberosa, and assessed the effects of plant and floral display size on pollination to understand how these factors influence reproductive success. This study found that I. tuberosa were pollinated exclusively by hymenopteran species, mainly during sunny days, and that plant and floral size did not affect fruit set and pollinator attraction. Thus, the sexual reproduction of I. tuberosa is fairly limited by pollinators and not by resource limitation.

Are pollinators the agents of selection on flower colour and size in irises?

“…This is in line with a study on another Mediterranean Iris species, I. tuberosa, where pollinators did not discriminate between tall/short or large/small flowers and rather visited morphologically different flowers in equal proportion (Pellegrino 2015). Additionally, pollinator limitation appears to be common throughout the genus, as identified in I. lacustris (Planisek 1987), I. versicolor (Wheelwright et al 2006), I. bismarckiana (Segal et al 2006), I. tuberosa (Pellegrino 2015), I. atropurpurea and I. haynei (Lavi and Sapir 2015). Nevertheless, we only measured proximate pollen limitation due to pollinators.…”

“…Furthermore, as commonly observed in rewardless plants (Aragón and Ackerman 2004, Tremblay et al 2005, Dormont et al 2010a, Sletvold et al 2016, Sonkoly et al 2016, we documented a low natural fruiting rate and a high pollinator limitation level for both studied species. For comparison, in I. tuberosa, a Mediterranean species producing nectar, natural fruiting rate is greater than 60% (Pellegrino 2015). However, number of seeds showed differences between colour morphs in supplementary hand pollination treatments, suggesting intrinsic differences between colour morphs.…”

“…Nevertheless, we only measured proximate pollen limitation due to pollinators. As both studied species are rhizomatous, fruit production could be costly and might appear to be resource limited over the plant's life (Ackerman and Montalvo 1990, Tarasjev 2005, Pellegrino 2015. Similarly, due to their self-incompatibility, geitonogamy and stigmate loading through pollinator visits to several flowers of the same genet could also account for low fruiting rates.…”

Stigmatic limitations on reproductive success in a paleotropical tree: causes and consequences

“…As per Pellegrino (2014), Pollen Limitation Index (PLI) was calculated as: $\text{PLI}=1-true(\frac{P_{\text{o}}}{P_{\text{c}}}true),$ where P o  = fruit-set in open pollinated pistils, $P_{\mathrm{normalc}}=\text{fruit}-\text{set in manual cross}-\text{pollinated pistils}$.…”

The Influence of Fire and Deforestation on the Floral Symmetry and Fitness of Adenocalymma nodosun (Bignoniaceae)

“…Thus, the shape, size, color of the floral structure and the quality of reward most likely result from coevolution characters between plants and their pollinators (Møller, 1995;Torezan-Silingardi, 2011;Pellegrino, 2015). Accordingly, recent studies are seeking to understand the relationship between the intraspecific variation in the morphology of the flowers and their reflection on the fitness of the plant, whereas pollinating insects exhibit preferences for visiting symmetrical flowers (Milligan et al, 2008;Frey & Bukoski, 2013;Daloso, 2014).…”