Flower Size as an Honest Signal in Royal Irises (Iris Section Oncocyclus, Iridaceae)

The effect of global change on the expression and evolution of floral traits

BACKGROUND

Pollinators impose strong selection on floral traits, but other abiotic and biotic agents also drive the evolution of floral traits and influence plant reproduction. Global change is expected to have widespread effects on biotic and abiotic systems, resulting in novel selection on floral traits in future conditions.

SCOPE

Global change has depressed pollinator abundance and altered abiotic conditions, thereby exposing flowering plant species to novel suites of selective pressures. Here, we consider how biotic and abiotic factors interact to shape the expression and evolution of floral characteristics (the targets of selection), including floral size, colour, physiology, reward quantity and quality, and longevity, amongst other traits. We examine cases in which selection imposed by climatic factors conflicts with pollinator-mediated selection. Additionally, we explore how floral traits respond to environmental changes through phenotypic plasticity and how that can alter plant fecundity. Throughout this review, we evaluate how global change might shift the expression and evolution of floral phenotypes.

CONCLUSIONS

Floral traits evolve in response to multiple interacting agents of selection. Different agents can sometimes exert conflicting selection. For example, pollinators often prefer large flowers, but drought stress can favour the evolution of smaller flowers, and the size of floral organs can evolve as a trade-off between selection mediated by these opposing actors. Nevertheless, few studies have manipulated abiotic and biotic agents of selection factorially to disentangle their relative strengths and directions of selection. The literature has more often evaluated plastic responses of floral traits to stressors than it has considered how abiotic factors alter selection on these traits. Global change will likely alter the selective landscape through changes in the abundance and community composition of mutualists and antagonists and novel abiotic conditions. We encourage future work to consider the effects of abiotic and biotic agents of selection on floral evolution, which will enable more robust predictions about floral evolution and plant reproduction as global change progresses.

A Flowering Morphological Investigation, Fruit Fatty Acids, and Mineral Elements Dynamic Changes of Idesia polycarpa Maxim

Idesia polycarpa Maxim is a high-value species of fruit oil with edible, abundant linoleic acid and polyphenols. Idesia polycarpa is described as a dioecious species, and the flowers are male; female and bisexual flowers are produced on separate plants. In order to explore the flower types of Idesia polycarpa, the morphology of its flowers and inflorescence were investigated in this study. The flower and inflorescence types, the diameter, and the flowering sequencing in male and female inflorescence were determined. We also detected the length, width, and fresh weight of leaves, shoots, and female inflorescence, as well as the length and fresh weight of the petiole during the development. Additionally, we compared the length, width, the length/width ratio, and the flowering density between 5- and 7-year-old female trees. The phenological period observation of Idesia polycarpa showed that the development process can be roughly divided into 12 stages, including bud burst, leaf expansion, inflorescence growth, initial flowering, full flowering, flower decline, initial fruiting, fruit enlargement, fruit color change, fruit ripening, post-ripening of fruit, and leaf fall periods. Furthermore, four elites' fruit determined the oil content and the composition of fatty acid content during the development. The dynamic of fatty acids contents, the palrnitic acid, palmitoleic acid, stearic acid, oleic acid, and linolenic acid contents were detected during the fruit development of four elites. Moreover, the mineral elements content of fruit of four elites during development were determined. The patterns of vegetative and reproductive growth in young dioecious trees of Idesia polycarpa provided the theoretical basis for artificial pruning and training.

Introduction to the Special Issue of Plants on "Advances in Plant Reproductive Ecology and Conservation Biology"

Plant reproductive ecology explores aspects of the biology and ecology of plants ranging from breeding systems, plant-pollinator interactions, seed germination, floral traits, and much more [...].

Visual-, Olfactory-, and Nectar-Taste-Based Flower Aposematism

Florivory, i.e., flower herbivory, of various types is common and can strongly reduce plant fitness. Flowers suffer two very different types of herbivory: (1) the classic herbivory of consuming tissues and (2) nectar theft. Unlike the non-reversibility of consumed tissues, nectar theft, while potentially reducing a plant's fitness by lowering its attraction to pollinators, can, in various cases, be fixed quickly by the production of additional nectar. Therefore, various mechanisms to avoid or reduce florivory have evolved. Here, I focus on one of the flowers' defensive mechanisms, aposematism, i.e., warning signaling to avoid or at least reduce herbivory via the repelling of herbivores. While plant aposematism of various types was almost ignored until the year 2000, it is a common anti-herbivory defense mechanism in many plant taxa, operating visually, olfactorily, and, in the case of nectar, via a bitter taste. Flower aposematism has received only very little focused attention as such, and many of the relevant publications that actually demonstrated herbivore repellence and avoidance learning following flower signaling did not refer to repellence as aposematism. Here, I review what is known concerning visual-, olfactory-, and nectar-taste-based flower aposematism, including some relevant cases of mimicry, and suggest some lines for future research.