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Abstract: Floral longevity is an important feature of a plant's reproductive strategy. The goal of this study was to examine flower life span in the shrub flame azalea (Rhododendron calendulaceum [...]

We tested the hypothesis that traits traditionally thought to function in pollination can also influence attack by floral herbivores. Because distylous species produce two different flower types, we used Gelsemium sempervirens, a distylous vine of southeastern USA, to examine the frequency and pattern of floral herbivory in relation to floral characteristics. Flowers of the short-styled morph had larger corollas but showed no difference in the volume or concentration of nectar produced. Over the 2 yr of this study, 20-30% of plants suffered floral herbivory. The pattern of damage was morph-specific. Long-styled flowers were more likely to have damaged pistils, while stamens were more often damaged in short-styled flowers. In this distylous species, exserted flower organs were more likely to be eaten. Such differential herbivory based on the position of floral organs within a flower may result in reduced fitness via either male (short-styled morph) or female function (long-styled morph). Key words: distyly; floral herbivory; flower predation; flower size; Gelsemium sempervirens; heterostyly; nectar production.

To determine the effects of density, genotype, and their interaction on individual seed mass in Raphanus sativus L., we replicated maternal and paternal families of seed across two planting densities in an experimental garden. Seeds were produced by a nested breeding design performed in the greenhouse. Among garden-raised plants, density had a strong negative effect on the mass of seeds produced. At low density, the identity of the greenhouse-grown maternal plants had a strong effect on F(sub 2) seed mass, while in high-density plots, there were no significant parental effects on mean seed mass. Significant parental genotype times density interactions contributed to variation in F(sub 2) seed mass. Norms of reaction for each of the 15 paternal sibships illustrate paternal family times density interactions. Three sibships exhibited significant declines in mean seed mass with increasing density; 12 sibships showed no change. Maternal family times density interaction effects on seed mass were also detected; among maternal sibships, mean seed mass at low density was negatively correlated with mean seed mass at high density. These results demonstrate: a) planting density has a strong effect on mean individual seed mass produced by adults; b) density influences the magnitude of maternal effects on progeny phenotype; and c) genotype times density interactions influence seed mass, potentially contributing to the maintenance of maternal genetic variation in seed mass in natural populations of wild radish.

Pollination networks are usually constructed and assessed by direct field observations which commonly assume that all flower visitors are true pollinators. However, this assumption is often invalid and the use of data based on mere visitors to flowers may lead to a misunderstanding of intrinsic pollination networks. Here, using a large dataset by both sampling floral visitors and analyzing their pollen loads, we constructed 32 networks pairs (visitation versus pollen transport) across one flowering season at four elevation sites in the Himalaya–Hengduan Mountains region. Pollen analysis was conducted to determine which flower visitors acted as potential pollinators (pollen vectors) or as cheaters (those not carrying pollen of the visited plants). We tested whether there were topological differences between visitation and pollen transport networks and whether different taxonomic groups of insect visitors differed in their ability to carry pollen of the visited plants. Our results indicated that there was a significantly higher degree of specialization at both the network and species levels in the pollen transport networks in contrast to the visitation networks. Modularity was lower but nestedness was higher in the visitation networks compared to the pollen transport networks. All the cheaters were identified as peripheral species and most of them contributed positively to the nested structure. This may explain in part the differences in modularity and nestedness between the two network types. Bees carried the highest proportion of pollen of the visited plants. This was followed by Coleoptera, other Hymenoptera and Diptera. Lepidoptera carried the lowest proportion of pollen of the visited plants. Our study shows that the construction of pollen transport networks could provide a more in‐depth understanding of plant–pollinator interactions. Moreover, it suggests that detecting and removing cheater interactions when studying the topology of other mutualistic networks might be also important. [ABSTRACT FROM AUTHOR]

Aims: Reproductive fitness of different floral phenotypes varies within and/or among populations. These variations are important to understand the process of natural selection and the evolution of floral traits. In this study, we focused on a distylous, self-incompatible species, Primula poissonii, to investigate fitness-related selection on floral traits. Our aim was to determine how traits vary as targets of natural selection and whether morph-specific selection occurs. Methods: This study was conducted at two sites (Yushuizhai at 2700 m and Haligu at 3200 m) in the Lijiang Alpine Botanical Garden, northwestern Yunnan, southwestern China. Insects visiting flowers of P. poissonii were observed, captured and identified. Randomly selected plants of long- and short-styled morphs were labeled. Five floral/inflorescence traits were measured including floral display, corolla width (CW), floral tube length (FTL), tube opening width (TOW) and floral scape height. Fruit and seed set were recorded. The total number of seeds per individual plant (plant fitness) and seed production per capsule (flower fitness) were calculated. Multiple regression analyses were used to quantify selection gradients. Important Findings: The frequencies of the two morphs did not deviate from the expected 1:1 ratio at both sites. Except for FTL, the four other traits did not differ significantly between the long- and short-styled morphs. Floral scape height, floral display and FTL differed between two sites. The selection regimes differed between two morphs and between two sites. At the Yushuizhai site, linear selection for shorter floral tubes was stronger in the short-styled morph. However, nonlinear selection on the floral display was stronger in the long-styled morph than selection on the short-styled morph. At the Haligu site, linear selection for a smaller corolla was stronger in the long-styled morph. A morph-specific nonlinear selection on CW and floral display was also detected. Morph-specific selections were detected through the estimation of flower fitness only in Haligu population. In this site, morph-specific linear selection was also detected for CW and floral display. Morph-specific nonlinear selection on traits was detected only in CW. We found that butterflies and sphingid moths dominated at Yushuizhai, while long-tongued bees dominated at Haligu. The difference in pollinator fauna suggested that selection on floral tubes may be due to differences in pollinator assemblages. Overall, variation of floral and/or inflorescence traits in P. poissonii was probably driven by pollinator selection. Selection regime differences between two morphs, in part, due the inter-morph divergences of sexual functions in distylous plant. [ABSTRACT FROM AUTHOR]