Variations of flower size and reproductive traits in self-incompatible Trollius ranunculoides (Ranunculaceae) among local habitats at Alpine Meadow

Abstract

For plants that rely on animals for pollination, the ability to attract the animals to their flowers can be a crucial component of fitness. A large number of studies have documented pollinators to be important selective agents driving the evolution of flower size and correlated traits on a large scale. In this paper, we studied variations of reproductive traits in self-incompatible Trollius ranunculoides (Ranunculaceae) among local habitats at Alpine Meadow. The results showed significant variations of floral size, seed mass per fruit and sex allocation (male/female mass ratio) between different habitats, where floral size and seed mass was not explained fully by variation of plant size among habitats. It suggested that other factors unrelated to plant size might also influence floral variation. However, in our manipulated experiment, it showed no effects of manipulated floral size not only on visit rate of effective pollinators (bees and flies) but also on female success (seed set, seed mass per fruit), irrespective of flower density. Consequently, we could not conclude that the variation of floral size in T. ranunculoides was due to phenotypic plasticity, or natural selection. But if selection occurred, it should not be mediated by pollinators. It was likely that variation of sex allocation between habitats lead to changes of flower or corolla size, because plant invested much less to male function (female-biased sex allocation and larger single seed mass) in shade habitat (bottom of bush) than other exposed habitats, to gain higher fitness. In addition, high-floral density in T. ranunculoides had a negative effect on service of main pollinator (bees) and female success. This situation would influence the strength of selection on floral size.

Relationship between acorn size and seedling morphological and physiological traits of Quercus ilex L. from different climates

“…Karst., Palmroth et al (1999) for Pinus sylvestris L., and Peuke et al (2002) for Fagus sylvatica L., Zhao et al (2007) for Trollius ranunculoides Hemsl., Baquedano et al (2008) for Q. coccifera L. and Pinus halepensis Mill., Zheng et al (2009) for Trigtonobalanus doichangensis (A. Camus) Forman. Fig.…”

Selection by Pollinators on Floral Traits in Generalized Trollius ranunculoides (Ranunculaceae) along Altitudinal Gradients

“…Flowering begins from early June to mid-July, and one flower generally lasts ∼8 d. T . ranunculoides is self-incompatible, and seed production depends on insect pollinators composed of bees, flies, ants and occasionally beetles [ 43 ].…”

“…T . ranunculoides is a self-incompatible hermaphrodite with a generalized pollination system [ 43 ], covering an extensive range of altitude in alpine meadows at Qinghai-Tibet Plateau. Flowers of T .…”

Optimal pollinator attraction strategies in Trollius ranunculoides Hemsl. (Ranunculaceae) at different altitudes: increased floral display or promotion of nectar output?

“…The plants are pollinated by insects such as bees and flies, i.e. by unspecialised pollinators (Zhao et al. 2007), because of the generalised floral morphology.…”