Phenology in a community context: Toward a better understanding of the causes and consequences of phenology in seasonal environments Contrasting altitudinal patterns of diversity between bumblebees and bumblebee-visited flowers: Poverty of bumblebee diversity in a high mountain of Japan Abstract Range shifts of mountain organisms toward higher elevations in response to global warming may result in spatial mismatches between plants and their pollinators. Here, we aimed to examine whether bumblebee diversity decreases in a high-altitude zone, and whether it parallels a decrease in the altitudinal diversity of bumblebee-visited plants. We surveyed the alpha diversities of flower-visiting bumblebees and bumblebee-visited plants along an altitudinal gradient on a Japanese high mountain.Then, we examined whether the alpha diversities of bumblebees and bumblebeevisited plants could be explained by altitude, or by other factors such as season, surveyed area and flower abundance. We found that a model including only altitude best explained bumblebee diversity, and that flower abundance and plant diversity had considerable value in explaining bumblebee diversity. In contrast, none of the studied factors explained plant diversity. Bumblebee diversity was minimal in the high-altitude zone (1,900-2,600 m a.s.l.), where the only dominant bumblebee species, Bombus beaticola, visited many species of flowering plants. In contrast, five to seven bumblebee species were distributed in the low-(700-1,300 m a.s.l.) and middle-(1,300-1,900 m a.s.l.) altitude zones. These results show that plantpollinator mutualism in high-altitude zone of a Japanese mountain is asymmetric: many bee-pollinated plants rely almost exclusively on one bumblebee species (B. beaticola) for pollination. Monitoring future changes in the distribution and abundance of B. beaticola is indispensable for the conservation of alpine plant in Japan. K E Y W O R D S alpine plant fauna, altitudinal change, Bombus beaticola, insect-plant interaction, mountain biodiversity

Geographic difference in pollinator fauna and variation in average pollinator size may lead to local adaptations of flower size that enhance pollen transfer efficiency. Here, we show that flower size (corolla tube length) of Prunella vulgaris varies both laterally and along elevational gradients, in parallel with local pollinator proboscis length. We measured geographic variation in corolla tube length and leaf length of P. vulgaris, and in proboscis length of its bumblebee pollinators, in 12 populations on three different mountains. In estimating pollinator proboscis length, we considered both the average proboscis length of each bumblebee species and the species composition of bumblebees visiting P. vulgaris flowers. We then ascertained whether pollinator proboscis length, elevation itself, or resource availability (indicated by leaf length) correlated with corolla tube length. We found that the local pollinator species composition varied along elevation and among mountain areas, and this variation corresponded to geographic variation in the average pollinator proboscis length. Similarly, corolla tube length of P. vulgaris varied along elevation and among mountain areas. We found that the corolla tube length variation was not associated with elevation itself or local resource availability but was strongly associated with local pollinator average proboscis length. Although corolla tube length was generally shorter at higher elevation, it was relatively longer in some high‐elevation populations, where bumblebees having long proboscis length (Bombus consobrinus and B. diversus) visited the flowers. Therefore, parallel changes in P. vulgaris corolla tube length and pollinator proboscis length occur across a wide geographic region in central Japan.

BackgroundGeographic differences in floral size sometimes reflect geographic differences in pollinator size. However, we know little about whether this floral size specialization to the regional pollinator size occurred independently at many places or occurred once and then spread across the distribution range of the plant species.ResultsWe investigated the relationship between the local floral size of flowers and local pollinator size in 12 populations ofLamium albumvar.barbatumon two different mountains in the Japan Alps. Then, using 10 microsatellite markers, we analyzed genetic differentiation among the 12 populations. The results showed that local floral size was correlated with the average size of relevant morphological traits of the local pollinators: floral size was greater in populations visited frequently by the largest flower visitors,Bombus consobrinusqueens, than it was in other populations. We also found that the degree of genetic similarity between populations more closely reflected interpopulation geographic proximity than interpopulation similarity in floral size.ConclusionsAlthough genetic similarity of populations was highly associated with geographic proximity, floral size varied independently of geographic proximity and was associated with local pollinator size. These results suggest that inL. albumvar.barbatum, large floral size evolved independently in populations on different mountains as a convergent adaptation to locally abundant large bumblebee species.

No abstract