Phylogenetic approaches resolve taxonomical confusion in Pedicularis (Orobanchaceae): Reinstatement of Pedicularis delavayi and discovering a new species Pedicularis milliana.

Morphological identification of Pedicularis depends on floral characters. However, some important characters may be lost during the process of pressing the specimen. Pedicularis delavayi was described from northwestern Yunnan, and widely adopted as a variety of P. siphonantha. Unfortunately, the name "P. siphonantha var. delavayi' incorrectly referred to P. milliana (a new species described in this study) or P. tenuituba in some herbarium specimens and publications. Moreover, phylogenetic relationships among P. delavayi, P. siphonantha and its allies (P. milliana and P. tenuituba) were not fully resolved. In this study, we sampled 76 individuals representing 56 taxa. Of them, 10 taxa were from P. siphonantha lineage, and 11 individuals of P. delavayi represented 9 populations. These species were named as P. siphonantha group on the basis of morphological similarity. Nuclear ribosomal internal transcribed spacer (nrITS) and four chloroplast genes/regions were used for phylogenetic analyses. Phylogenetic analyses showed that the P. siphonantha group was polyphyletic: P. delavayi was sister to P. obliquigaleata in clade A; and the remaining species of P. siphonantha group were monophyletic in clade B, named as P. siphonantha lineage. In the P. siphonantha lineage, P. milliana, P. siphonantha, and P. tenuituba were well supported as monophyletic, and P. dolichosiphon was sister to P. leptosiphon. Morphologically, P. delavayi differs from species of the P. siphonantha lineage in having a long petiole (~ 50 mm) and pedicel (~ 40 mm), a ridged corolla tube, and a folded lower-lip of the corolla. Therefore, both morphological characters and phylogenetic evidence strongly supported to reinstate P. delavayi as an independent species and describe P. milliana as new species. In addition, P. neolatituba was proposed to reduce as a new synonymy of P. delavayi.

Geographic consistency and variation in conflicting selection generated by pollinators and seed predators.

BACKGROUNDS AND AIMS: Floral traits that attract pollinators may also attract seed predators, which, in turn, may generate conflicting natural selection on such traits. Although such selection trade-offs are expected to vary geographically, few studies have investigated selection mediated by pollinators and seed predators across a geographic mosaic of environments and floral variation. METHODS: Floral traits were investigated in 14 populations of the bumble-bee-pollinated herb, Pedicularis rex, in which tubular flowers are subtended by cupular bracts holding rain water. To study potentially conflicting selection on floral traits generated by pollinators and florivores, stigmatic pollen loads, initial seed set, pre-dispersal seed predation and final viable seed production were measured in 12-14 populations in the field. KEY RESULTS: Generalized Linear Model (GLM) analyses indicated that the pollen load on stigmas was positively related to the exsertion of the corolla beyond the cupular bracts and size of the lower corolla lip, but so too was the rate of seed predation, creating conflicting selection on both floral traits. A geographic mosaic of selection mediated by seed predators, but not pollinators, was indicated by significant variation in levels of seed predation and the inclusion of two-, three- and four-way interaction terms between population and seed predation in the best model [lowest corrected Akaike Information Criterion (AICc)] explaining final seed production. CONCLUSIONS: These results indicate opposing selection in operation: pollinators generated selection for greater floral exsertion beyond the bracts, but seed predators generated selection for reduced exsertion above the protective pools of water, although the strength of the latter varied across populations.

Floral nectary, nectar production dynamics, and floral reproductive isolation among closely related species of Pedicularis.

Floral nectar is thought to be one of the most important rewards that attract pollinators in Pedicularis; however, few studies have examined variation of nectary structure and/or nectar secretion in the genus, particularly among closely related species. Here we investigated nectary morphology, nectar quality, and nectar production dynamics in flowers of Pedicularis section Cyathophora. We found a conical floral nectary at the base of the ovary in species of the rex-thamnophila clade. Stomata were found on the surface of the nectary, and copious starch grains were detected in the nectary tissues. In contrast, a semi-annular nectary was found in flowers of the species of the superba clade. Only a few starch grains were observed in tissues of the semi-annular nectary, and the nectar sugar concentration in these flowers was much lower than that in the flowers of the rex-thamnophila clade. Our results indicate that the floral nectary has experienced considerable morphological, structural, and functional differentiation among closely related species of Pedicularis. This could have affected nectar production, leading to a shift of the pollination mode. Our results also imply that variation of the nectary morphology and nectar production may have played an important role in the speciation of sect. Cyathophora.

Are long corolla tubes in Pedicularis driven by pollinator selection?

The evolution of long corolla tubes has been hypothesized to be driven by long-tongued pollinators. Corolla tubes in Pedicularis species can be longer than 10 cm which may function as flower stalks to increase visual attractiveness to pollinators because these species provide no nectar and are pollinated by bumblebees. The corolla tube length was manipulated (shorter or longer) in two Pedicularis species in field to examine whether longer tubes are more attractive to pollinators and produce more seeds than short tubes. Our results did not support the pollinator attraction hypothesis, leaving the evolution of long tubes in Pedicularis remains mysterious.

Towards a comprehensive phylogeny of the large temperate genus Pedicularis (Orobanchaceae), with an emphasis on species from the Himalaya-Hengduan Mountains.

BACKGROUND: Striking interspecific variations in floral traits of the large temperate genus Pedicularis have given rise to controversies concerning infra-generic classifications. To date, phylogenetic relationships within the genus have not been well resolved. The main goal of this study is to construct a backbone phylogeny of Pedicularis, with extensive sampling of species from the Himalaya-Hengduan Mountains. Phylogenetic analyses included 257 species, representing all 13 informal groups and 104 out of 130 series in the classification system of Tsoong, using sequences of the nuclear ribosomal internal transcribed spacer (nrITS) and three plastid regions (matK, rbcL and trnL-F). Bayesian inference and maximum likelihood methods were applied in separate and combined analyses of these datasets. RESULTS: Thirteen major clades are resolved with strong support, although the backbone of the tree is poorly resolved. There is little consensus between the phylogenetic tree and Tsoong's classification of Pedicularis. Only two of the 13 groups (15.4 %), and 19 of the 56 series (33.9 %) with more than one sampled species were found to be strictly monophyletic. Most opposite-/whorled-leaved species fall into a single clade, i.e. clade 1, while alternate leaves species occur in the remaining 12 clades. Excluding the widespread P. verticillata in clade 1, species from Europe and North America fall into clades 6-8. CONCLUSIONS: Our results suggest that combinations of morphological and geographic characters associated with strongly supported clades are needed to elucidate a comprehensive global phylogeny of Pedicularis. Alternate leaves are inferred to be plesiomorphic in Pedicularis, with multiple transitions to opposite/whorled phyllotaxy. Alternate-leaved species show high diversity in plant habit and floral forms. In the Himalaya-Hengduan Mountains, geographical barriers may have facilitated diversification of species with long corolla tubes, and the reproductive advantages of beakless galeas in opposite-/whorled-leaved species may boost speciation at high altitude.

The presence of co-flowering species facilitates reproductive success of Pedicularis monbeigiana (Orobanchaceae) through variation in bumble-bee foraging behaviour.

Background and Aims The presence of co-flowering species can alter pollinator foraging behaviour and, in turn, positively or negatively affect the reproductive success of the focal species. Such interactions were investigated between a focal species, Pedicularis monbeigiana, and a co-flowering species, Vicia dichroantha, which was mediated by behaviour alteration of the shared bumble-bee pollinator. Methods Floral display size and floral colour change of P. monbeigiana were compared between pure (P. monbeigiana only) and mixed (P. monbeigiana and V. dichroantha) plots in two populations. Pollinator visitation rates, interspecific floral switching and successive within-plant pollinator visits were recorded. In addition, supplemental pollination at plant level was performed, and the fruit set and seed set were analysed in pure and mixed plots with different densities of P. monbeigiana. Key Results Pollinator visitation rates were dramatically higher in mixed plots than in pure plots. The higher pollinator visitation rates were recorded in both low- and high-density plots. In particular, successive flower visits within an individual plant were significantly lower in mixed plots. Supplemental pollination significantly increased fruit set and seed set of individuals in pure plots, while it only marginally increased seed set per fruit of plants in mixed plots. Conclusions The presence of V. dichroantha can facilitate pollination and increase female reproductive success of P. monbeigiana via both quantity (mitigating pollinator limitation) and quality (reducing geitonogamy) effects. This study suggests that successive pollinator movements among flowers within a plant, as well as pollinator visitation rates and interspecific flower switching, may be important determinants of the direction and mechanisms of interaction between species.