An Evolutionary And Pollination Biology Study Of The Floral Traits Of Lonicera Species In Qinling Area

Although pollinators commonly attributed to act as selective agents on floral traits,determining the extent to which they have affected to the diversity of plants requires phylogenetic analyses.However,in the evolutionary process of plants,the diversity of floral traits,which is generated by some innovative events(e.g.pollinator shifts),will be shown in clades by phylogenetic analysis.In this study,we aimed at whether pollinators could drive diversification of floral orientation and nectar secretion in Lonicera species,which are distributed in Qinling area,and the macroevolution of these floral traits across multiple-related species base on phylogenetic analysis.Floral orientation has been suggested to be a functional floral trait that can enhance reproductive fitness.Nectar is presented inside flowers close to reproductive success and rewards animals to persistently visit flowers.We used six gene regions to reconstruct the phylogenetic tree of Lonicera species which were distributed in Qinling area to find their phylogenetics.Based on phylogenetic relationships,Lonicera species were identified by incorporating the species' floral orientation(up-vs.downward)and pollinator types.Furthermore,transitions in floral orientation were evaluated together with pollinator shifts,and seven sympatric species were used to detect the influence of the floral orientation on pollination and reproductive success.Moreover,the relationship between the abiotic factor(temperature)and the angle of floral orientation was investigated.We also quantified corolla tube,nectar secretion and nectary size of 11 Lonicera species,and used phylogenetic comparative analysis and structural equation model to seek relationship between them,used general linear model to explore correlation between these floral traits with pollinators.Results of Bayesian analysis strongly support the classic taxonomy system of Lonicera.Most Lonicera species do not produce seed,when they are pollinated self-pollen by hand.Floral orientation in Lonicera is phylogenetically constrained,while pollinator shifts can lead to transitions between up-and downward orientation.Additionally,the angle of floral orientation increased with flowering phenology from spring to summer,and changing floral orientation significantly decreased pollination and seed production.Moreover,the average daily temperature during flowering phenology was significantly correlated with the angle of floral orientation(b=0.1434 ± 0.0313,t=4.578,P=0.00596).In Lonicera,corolla tube length and nectar secretion volume have significant phylogenetic constraints,corolla tube length has tight relationship with nectar secretion volume(b=3.40 ± 0.47,P<0.001)and nectar concentration(b=-0.0081 ±0.0023,P=0.0071).Our results indicate that pollinator shifts could be important innovative events,leading to the diversification of floral orientation.Pollinators could drive the diversity of corolla tube length and nectar secretion.Pendent flowers might help decrease heat loss to adapt to cold conditions.Corolla tube length and nectar secretion need be seemed as a kind of floral integration.This study disentangled the influences of historical events and local adaptation on the evolution of floral orientation and nectar secretion.