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Abstract Some aphid species produce a soldier caste with enlarged forelegs and horns (weapons). It has been hypothesised that the evolution of morphological specialization by soldiers in social aphids is accelerated by high predation pressure, but this possibility has not been tested. Here, we investigated the relationship between local predator abundance and soldiers’ weapon size and aggressiveness in a prey–predator system comprising a eusocial aphid, Ceratovacuna japonica, and its predators (larvae of the butterfly Taraka hamada and of the moth Atkinsonia ignipicta) in two populations with different predator abundances. We found that the soldiers in the predator-abundant population had larger weapons and were more aggressive than those in the population with lower predator abundance. Furthermore, the soldiers’ defensive prowess (evaluated as the survival of aphids in the presence of predators) was greater in the predator-abundant population. These results provide the first evidence that a population of eusocial aphids experiencing high predation pressure has soldiers with pronounced defensive traits and defensive prowess.

To understand the reproductive ecology of a plant species with both selfing and outcrossing reproductive systems, it is important to know how selfed individuals contribute to the maintenance of a population. Further, examination of the magnitude of inbreeding depression after pollination is essential for the accurate measurement of reproductive success. In this study, we investigated the characteristics of viable seeds and seedlings of Rhododendron kaempferi Planch. in a region where the bumblebee pollinator Bombus ardens Smith, 1879 are abundant. In a hand-pollination experiment, the fruit set from self-pollination was 32%, significantly lower than that from outcross-pollination (81%). The number of seeds per fruit from self-pollination was one sixth the number from outcross-pollination. However, the number of seeds per fruit was negatively correlated with the mass per seed. In addition, the germination rate was low when the seed mass was light. Although selfed seeds could germinate, 89% of the seedlings died within a year. The inbreeding depression coefficient one year after sowing was very high (0.89). These results indicate that R. kaempferi shows extremely strong selection for outcrossing but maintains a slight selfing potential in a natural population in central Japan. Key words: bumblebee, germination, inbreeding depression, rhododendron, seed. Afin de comprendre l'ecologie de la reproduction d'especes vegetales dont les systemes de reproduction sont a la fois endogames et par croisements eloignes, il est important de savoir comment les individus endogames contribuent au maintien d'une population. De plus, l'examen de l'ampleur de la depression de consanguinite apres la pollinisation est essentiel pour mesurer precisement le succes de la reproduction. Dans cette etude, les auteurs ont examine les caracteristiques des graines et des plantules viables de Rhododendron kaempferi Planch. dans une region ou le bourdon pollinisateur Bombus ardens Smith, 1879 est abondant. Lors d'une experience de pollinisation manuelle, la nouaison issue de l'autopollinisation etait de 32 %, soit nettement moins que celle issue de la pollinisation croisee (81 %). Le nombre de graines par fruit provenant de l'autopollinisation etait un sixieme de celui provenant de la pollinisation croisee. Cependant, le nombre de graines par fruit etait correle negativement avec le poids par graine. Par ailleurs, le taux de germination etait faible lorsque le poids des graines etait leger. Bien que les graines endogames aient pu germer, 89 % des plantules mouraient au cours de la premiere annee. Le coefficient de depression de consanguinite un an apres le semis etait tres eleve (0,89). Ces resultats indiquent que R. kaempferi presente une selection extremement forte pour les croisements eloignes, mais maintient un leger potentiel d'autofecondation dans une population naturelle du centre du Japon. [Traduit par la Redaction] Mots-cles : bourdon, germination, depression de consanguinite, rhododendron, graine., Introduction Inbreeding depression, defined as the reduction in fitness of progeny derived from inbreeding relative to that of progeny derived from outcrossing, has long been an important topic in the [...]

Background and aims – Previous researchers have demonstrated that geographic variation in pollinator community composition can generate diversity in the floral traits of animal-pollinated plants. Our study focused on the bumblebee-pollinated white dead-nettle Lamium album var. barbatum. Geographic variation in corolla length of this species is known to be correlated with regional pollinator size. The aim of this study is to clarify whether size-matching between flower and pollinator affects seed set in L. album.Material and methods – In the present study, we investigated two L. album populations on Mount Norikura, central Japan. We determined the pollinator community composition and corolla length during the flowering period of L. album and recorded seed set after a single visit by different pollinator categories.Key results – We observed that the main pollinators of L. album were bumblebee queens and workers. Bumblebee queens visited flowers more frequently than workers during peak flowering. Furthermore, size-matching between flowers and bumblebee queens, but not workers, strongly promoted seed set. These results suggest that L. album flower size is adapted to bumblebee queens, the main pollinator during peak flowering season in our study sites.

Most flowering plants are visited by various pollinator insects. To understand floral specialization for pollinators, the relative importance of different flower visitors to the focal plant species should be revealed. In the present study, we observed the insects that visited the orchid Platanthera hologlottis throughout the day and night using interval timer photography to reveal the relative importance of diurnal and nocturnal flower visitors. We observed visitation by both diurnal (e.g. the butterfly Ochlodes ochraceus) and nocturnal (e.g. the moth Thysanoplusia intermixta) insects and examined their relative contribution to fruit production and pollinarium removal experimentally. Results showed that the fitness was higher in flowers visited by nocturnal insects than in those visited by diurnal insects. These results suggest that the floral traits of P. hologlottis may be specialized for nocturnal flower visitors rather than diurnal flower visitors.

Examination of the efficacy of pollinators that are not morphologically matched to a flower’s shape can deepen our understanding of the main pollinators of a plant species. In central Japan, Rhododendron japonicum is visited much more frequently by bumblebees than by butterflies although its flower shape is more suited for pollination by large butterflies. Here, we observed flower-visiting behaviour of Bombus diversus queens and the alpine black swallowtail butterfly, Papilio maackii, and compared their efficacy as pollinators. Papilio maackii always touched the stigma during a flower visit, whereas B. diversus queens did so during just 54% of their flower visits. As bumblebees visit neighboring flowers of a R. japonicum tree in sequence not like Papilio maackii, we hypothesized that they deliver self pollen to R. japonicum so that the fruit set would be low. However, the fruit set in a bumblebee-dominated area was 72.5%, significantly higher than that by hand-pollination with self pollen (31.4%). This suggests that R. japonicum can obtain sufficient fruits by B. diversus queens although its flower shape morphologically matches to pollination by swallowtail butterflies.

Abstract Cimicifuga simplex has three genetically and ecologically distinct pollination morphs with different flowering phenology, flower sex expressions, and selfing rates. A previous study showed that strong protandry in hermaphroditic flowers of C. simplex causes there to be seasonal minority sexes; for example, unisexual female ramets are advantageous in the first half of the flowering season and bloom then (minority sex hypothesis). That study, however, did not distinguish among the three pollination morphs of C. simplex. We investigated seasonal sex ratio changes and pollinator environments of the three morphs to verify and expand the minority sex hypothesis. We investigated flowering phenology, pollinator quantity and quality, seasonal population sex ratio dynamics, and stamen/ovule ratios in hermaphroditic flowers. We also examined the seasonal female reproductive success of hermaphroditic flowers, and the effect of male flower excision on fruit set by morph II hermaphroditic flowers. Morph I (mainly hermaphroditic and female ramets) had high pollinator quality and quantity. Fruit set of hermaphroditic ramets was high throughout the flowering season. Morph II (hermaphroditic and andromonoecious ramets) had low pollinator quality, and few pollinators visited near the beginning and end of the season. Removal of male flowers led to a pollen limitation. Morph III (hermaphroditic ramets and a high selfing rate) had very low pollinator abundance throughout the flowering season, and male and female phases largely overlapped. The scarcity of male flowers in morph I is likely a result of the high pollinator quantity and quality. The high fruit set suggests that no pollen limitation existed. The low pollinator quality and quantity of the morph II population caused it to suffer from pollen limitation and may explain the absence of unisexual female ramets in this morph. The high selfing rate of morph III may be due to the extremely low pollinator abundance. Theoretical studies have indicated that the optimal investment allocation to male and female functions depends on whether a pollen limitation exists. In C. simplex, the observed relationships between pollinator environment and reproductive systems are consistent with these theoretical models.

Relationships between flower visitor composition and floral traits help us to understand floral evolution. Swallowtail butterflies have been assumed to be the main pollinators of Rhododendron kaempferi and R. japonicum based on their floral shapes, and R. kaempferi was reported to be pollinated by butterflies in southern Japan. In the mountains of central and northern Japan, however, bumblebees are abundant and candidate pollinators of Rhododendron. We found that visitation frequencies of bumblebees were higher than those of swallowtail butterflies to both of the Rhododendron species at three study sites in the mountains of central Japan. R. japonicum pollen adhered to the bodies of both floral visitors. Further, the nectar sugar concentration of R. kaempferi was in the preference range of bumblebees, whereas that of R. japonicum was suited to both bumblebees and butterflies. Taken together, these findings support the hypothesis that bumblebees are potentially also important pollinators of R. kaempferi and R. japonicum in mountains of central Japan, where they are more abundant than swallowtail butterflies.

Myrmecophilus crickets (Myrmecophilidae, Orthoptera) are typical ant guests. In Japan, about 10 species are recognized on the basis of morphological and molecular phylogenetic frameworks. We focused on two of these species, M. kinomurai and M. kubotai, and compared their host and habitat use. Previous work based on a limited sampling effort suggested that these two species share some ant species as hosts, but that their habitat (open versus shaded) preferences differ. Here, on the basis of exhaustive sampling across Japan, we confirmed that M. kinomurai and M. kubotai do not differ in their host ant preferences: both prefer formicine ants as hosts. As for habitat preferences, M. kubotai occurred significantly more often in open habitats than in shaded ones (P < 0.05). In contrast, M. kinomurai showed no habitat preference in areas where M. kubotai did not occur. However, M. kinomurai showed an obvious preference for shaded environments in areas of sympatry with its potential competitor M. kubotai. This pattern suggests that interspecific competition between M. kinomurai and M. Kubotai is a factor causing habitat differentiation in areas of sympatry.

Seed dispersal by ants (myrmecochory) is an important life phase in flowering herbs of temperate deciduous forests, and long dispersal is basically preferable in terms of plant fitness. Although it is known that larger ants transport seeds farther, previous studies conflicted whether larger seeds are preferred by large ants. We examine how seed size and ant body size influence removal rate of seeds and their dispersal distance by ants. The obligate myrmecochorous, large-seed bearing Viola hondoensis and ant-ballistic diplochorous, small-seed bearing Viola spp. and Corydalis pallida were comparatively investigated. 1) Ant preference: attraction rate and transportation rate of large V. hondoensis seeds by ants were consistently high regardless of the disperser ant size whilst those rates of small diplochorous seeds were conspicuously lower for large Aphaenogaster ants than for small Pheidole ants, suggesting small seeds are not adapted to be carried by large ants. 2) Dispersal distance: large V. hondoensis seeds were transported for a long distance because they were carried by both large and small ants while the small diplochorous seeds were transported for a short distance because they were carried only by small ants. These results suggest that large seeds are advantageous to attract large ants and to be farther dispersed as far as ant-mediated dispersal is concerned. On the other hand, the diplochorous small seeds do not attract large ants, and so are transported short by ants although they disperse their seeds by ballistic dispersal.

A previously reported mitochondrial DNA (mtDNA) phylogeny of Crematogaster (subgenus Decacrema) ants inhabiting Macaranga myrmecophytes indicated that the partners diversified synchronously and their specific association has been maintained for 20 million years. However, the mtDNA clades did not exactly match morphological species, probably owing to introgressive hybridization among younger species. In this study, we determined the congruence between nuclear simple sequence repeat (SSR, also called microsatellite) genotyping and mtDNA phylogeny to confirm the suitability of the mtDNA phylogeny for inferring the evolutionary history of Decacrema ants. Analyses of ant samples from Lambir Hills National park, northeastern Borneo, showed overall congruence between the SSR and mtDNA groupings, indicating that mtDNA markers are useful for delimiting species, at least at the local level. We also found overall high host-plant specificity of the SSR genotypes of Decacrema ants, consistent with the specificity based on the mtDNA phylogeny. Further, we detected cryptic genetic assemblages exhibiting high specificity toward particular plant species within a single mtDNA clade. This finding, which may be evidence for rapid ecological and genetic differentiation following a host shift, is a new insight into the previously suggested long-term codiversification of Decacrema ants and Macaranga plants.

Even if the generation time of I B. esakii i is halved, the host remains univoltine, so the target of parasitism is not the next generation of the host but the same generation of the host that is currently being parasitized. Despite this disadvantage of faster growth of I B. esakii i in superparasitized hosts, over 80% of I B. esakii i were in superparasitized hosts as described earlier; thus, for I B. esakii i , superparasitism is not a rare, unfortunate event but is experienced by many individuals. Keywords: density-dependent plasticity; dwarf bamboo; host-parasite interaction; phenology; stylopization; twisted-winged parasite EN density-dependent plasticity dwarf bamboo host-parasite interaction phenology stylopization twisted-winged parasite 1 5 5 11/03/22 20221101 NES 221101 Strepsiptera is an order of parasitic insects that exhibit extreme sexual dimorphism: Adult males are free-living, winged insects that spend their lives seeking females to fertilize (Pohl & Beutel, 2005), whereas females are neotenic and completely endoparasitic within their hosts (except for basal parasitoid groups). Except for a short period in early summer, about half of the sampled I M. obnubilus i individuals were nymphs (Appendix S1: Table S1; Nakase & Kato, 2011); thus, when fast-growing I B. esakii i females become adults and release first instar larvae, host nymphs of the same generation are available for parasitism. [Extracted from the article]

Predators generally have traits that enable them to efficiently capture their prey and thus improve their survival. Natural selection should also favor traits of predators that improve the survival rate of their eggs, which are immobile and incapable of active resistance. We hypothesized that eggs of Atkinsonia ignipicta, a specialist predator of the eusocial aphid Ceratovacuna japonica, exhibit a defensive trait against aphid soldiers. We found that the hatchability of A. ignipicta eggs did not differ significantly between the experimental treatments with and without soldiers, which suggests that the eggs have a defensive trait that protects them from soldier aphids. Moreover, although the soldiers occasionally exhibited attack behavior when they encountered an egg, they did not continue the attack. We have observed a similar interruption of attack behavior by soldiers that attacked their aphid siblings by mistake, suggesting that the eggs may chemically mimic the soldiers' siblings. This study thus provides evidence for adaptation in a specialist predator of a eusocial aphid.

Myrmecophilus ant crickets (Orthoptera: Myrmecophilidae) are typical ant guests. In Japan, about 10 species are recognized on the basis of morphological and molecular phylogenetic frameworks. Some of these species have restricted host ranges and behave intimately toward their host ant species (i.e., they are host specialist). We focused on one species, M. tetramorii, which uses the myrmicine ant Tetramorium tsushimae as its main host. All but one M. tetramorii individuals were collected specifically from nests of T. tsushimae in the field. However, behavioral observation showed that all individuals used in the experiment received hostile reactions from the host ants. There were no signs of intimate behaviors such as grooming of hosts or receipt of mouth-to-mouth feeding from hosts, which are seen in some host-specialist Myrmecophilus species among obligate host-ant species. Therefore, it may be that M. tetramorii is the species that is specialized to exploit the host by means other than chemical integration.

We investigated the genetic diversification of the mountain ant, Myrmica kotokui, in the Japanese Alps by using molecular phylogenetic analyses. Myrmica kotokui is widely distributed in Japan, and in the central Japanese Alps it is found only between elevations of approximately 1000 to 2000 m. We hypothesized that genetically distinct clades of this ant species might inhabit different mountain ranges in central Japan. To test this hypothesis, we reconstructed a molecular phylogeny using the DNA sequences of the mitochondrial cytochrome oxidase I gene and the nuclear long-wavelength rhodopsin gene of M. kotokui specimens collected from six mountain ranges in the Japanese Alps. The phylogeny showed four highly differentiated clades. However, the correspondence between the clades and morphological species was a little confusing. Two clades were composed only of M. kotokui specimens, whereas the other two clades were composed of multispecies, suggesting the possibility of multispecies composition of putative M. kotokui. The distribution pattern of these clades did not support our hypothesis of geographical differentiation, because two were distributed across all ranges, and a third was distributed in five of the six ranges. On the other hand, we found a pattern in the altitudinal distribution of the clades: one clade was distributed only at higher elevations, and the others were distributed at lower elevations. Thus, the ant clades do not show geographical segregation by mountain range, but they do show altitudinal differences.

Geographic differences in floral traits may reflect geographic differences in effective pollinator assemblages. Independent local adaptation to pollinator assemblages in multiple regions would be expected to cause parallel floral trait evolution, although sufficient evidence for this is still lacking. Knowing the intraspecific evolutionary history of floral traits will reveal events that occur in the early stages of trait diversification. In this study, we investigated the relationship between flower spur length and pollinator size in 16 populations of Aquilegia buergeriana var. buergeriana distributed in four mountain regions in the Japanese Alps. We also examined the genetic relationship between yellow‐ and red‐flowered individuals, to see if color differences caused genetic differentiation by pollinator isolation. Genetic relationships among 16 populations were analyzed based on genome‐wide single‐nucleotide polymorphisms. Even among populations within the same mountain region, pollinator size varied widely, and the average spur length of A. buergeriana var. buergeriana in each population was strongly related to the average visitor size of that population. Genetic relatedness between populations was not related to the similarity of spur length between populations; rather, it was related to the geographic proximity of populations in each mountain region. Our results indicate that spur length in each population evolved independently of the population genetic structure but in parallel in response to local flower visitor size in different mountain regions. Further, yellow‐ and red‐flowered individuals of A. buergeriana var. buergeriana were not genetically differentiated. Unlike other Aquilegia species in Europe and America visited by hummingbirds and hawkmoths, the Japanese Aquilegia species is consistently visited by bumblebees. As a result, genetic isolation by flower color may not have occurred. [ABSTRACT FROM AUTHOR]

[Display omitted] • We collected gall midges (Cecidomyiidae) from Cimicifuga simplex herbs. • Gall midges belonging to five clades were collected from three C. simplex ecotypes. • The cryptic diversity of phytophagous insects was nested within that of the plants. • Plant diversification spurs further diversification of phytophagous insects. Studying the diversification patterns of species-rich phytophagous insect taxa can help us understand the factors that cause species diversification. We conducted a molecular phylogenetic analysis of the mitochondrial COI gene of larvae of gall midges (Diptera: Cecidomyiidae) using three genetically differentiated morphs of Cimicifuga simplex plants and found that the gall midges could be divided into five major clades. Gall midges collected from morph I of C. simplex belonged to four Schizomyia clades. Gall midges collected from morph II of C. simplex belonged to one of the four Schizomyia clades collected from morph I. Gall midges collected from morph III belonged one Contarinia clade. On morphs I and II of C. simplex , the Schizomyia species induced galls on the flower bud, whereas on morph III of C. simplex , the Contarinia species was collected from normal fruits (not gall inducer); thus, morph III plants were used differently by gall midges than plants of morphs I and II. These results indicate that the cryptic diversity of these phytophagous insects correspond to that of plant ecotypes, and suggests that the diversification of the host plant contributed to parallel diversification of the phytophagous gall midges. [ABSTRACT FROM AUTHOR]

The behavioural patterns of flower-visiting insects are influenced by floral display size, floral reward, etc. We tested whether insects of various taxa visiting Cimicifuga simplex would change their behaviour between hermaphroditic and female flowers. Male-phase flowers of hermaphroditic ramets provide flower visitors with nectar and pollen as rewards, whereas female flowers of female ramets provide flower visitors with only nectar. The appearance of the both sexes in C. simplex is different with hermaphrodite being relatively large and female ramet being relatively small. Therefore, to investigate how sexual differences in floral rewards and conspicuousness affect flower visitor behaviour, we compared flower visitor behaviour between male-phase hermaphroditic ramets and female ramets. C. simplex was visited by the bumblebee Bombus beaticola beaticola (Hymenoptera), Vespula flaviceps (Hymenoptera), Anthomyiidae spp. (Diptera), Episyrphus balteatus (Diptera), and Pidonia aegrota (Coleoptera). The visitation frequency of all visitors, especially of bumblebees and dipteran insects, to male-phase hermaphroditic ramets was higher than that to female ramets. The number of flowers contacted per single visit to an inflorescence was significantly higher for hermaphroditic ramets than for female ramets in bumblebees, but no difference was found in other insect groups. These results suggest that bumblebees visit the low-reward female ramets less often than male-phase hermaphroditic ramets, and they stay on female ramets for a shorter time. In contrast, insects other than bumblebees seem to decide which flowers to visit according to how conspicuous the flowers are, but once they visit a ramet they continue to visit flowers on the ramet even if no pollen rewards there are. [ABSTRACT FROM AUTHOR]

Background and aims - Previous researchers have demonstrated that geographic variation in pollinator community composition can generate diversity in the floral traits of animal-pollinated plants. Our study focused on the bumblebee-pollinated white dead-nettle Lamium album var. barbatum. Geographic variation in corolla length of this species is known to be correlated with regional pollinator size. The aim of this study is to clarify whether size-matching between flower and pollinator affects seed set in L. album. Material and methods - In the present study, we investigated two L. album populations on Mount Norikura, central Japan. We determined the pollinator community composition and corolla length during the flowering period of L. album and recorded seed set after a single visit by different pollinator categories. Key results - We observed that the main pollinators of L. album were bumblebee queens and workers. Bumblebee queens visited flowers more frequently than workers during peak flowering. Furthermore, sizematching between flowers and bumblebee queens, but not workers, strongly promoted seed set. These results suggest that L. album flower size is adapted to bumblebee queens, the main pollinator during peak flowering season in our study sites. [ABSTRACT FROM AUTHOR]

Background: Geographic 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. Results: We investigated the relationship between the local floral size of flowers and local pollinator size in 12 populations of Lamium album var. barbatum on 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 consobrinus queens, 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. Conclusions: Although 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 in L. album var. barbatum, large floral size evolved independently in populations on different mountains as a convergent adaptation to locally abundant large bumblebee species. [ABSTRACT FROM AUTHOR]

Most flowering plants are visited by various pollinator insects. To understand floral specialization for pollinators, the relative importance of different flower visitors to the focal plant species should be revealed. In the present study, we observed the insects that visited the orchid Platanthera hologlottis throughout the day and night using interval timer photography to reveal the relative importance of diurnal and nocturnal flower visitors. We observed visitation by both diurnal (e.g. the butterfly Ochlodes ochraceus) and nocturnal (e.g. the moth Thysanoplusia intermixta) insects and examined their relative contribution to fruit production and pollinarium removal experimentally. Results showed that the fitness was higher in flowers visited by nocturnal insects than in those visited by diurnal insects. These results suggest that the floral traits of P. hologlottis may be specialized for nocturnal flower visitors rather than diurnal flower visitors. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

About 10% of aphid species show host alternation. These aphids migrate between primary and secondary host plant species in spring and autumn. Host alternation has not been observed in subfamily Lachninae, although it has been suggested on the basis of circumstantial evidence that Stomaphis japonica (Takahashi) may alternate its host between Quercus serrata (Murray) and Quercus acutissima (Carruth). However, a molecular phylogenetic study has indicated that the Stomaphis individuals feeding on these two plant species belong to two different lineages and aphids feeding on Q. acutissima and Pinus densiflora (Sieb. & Zucc.) belong to the same lineage. Here, we examined host alternation in Stomaphis species by comparing molecular phylogenetic identities, morphological features, and life cycles. The molecular analysis and morphological examination showed that aphids feeding on Q. acutissima were the same as those feeding on P. densiflora , whereas aphids feeding on Q. serrata were different from those feeding on Q. acutissima or on P. densiflora. Furthermore, winged aphids were observed on both Q. acutissima and P. densiflora in autumn, but we did not observe winged aphids on Q. serrata. These results indicate that Stomaphis (Walker) individuals feeding on Q. serrata and Q. acutissima belong to two species, one that feeds year-round on Q. serrata, and another, heteroecious species that feeds on P. densiflora as a primary host and on Q. acutissima as a secondary host. This study documents host alternation in subfamily Lachninae for the first time and discusses the acquisition of host alternation by Stomaphis from evolutionary and ecological perspectives. [ABSTRACT FROM AUTHOR]

Cimicifuga simplex has three genetically and ecologically distinct pollination morphs with different flowering phenology, flower sex expressions, and selfing rates. A previous study showed that strong protandry in hermaphroditic flowers of C. simplex causes there to be seasonal minority sexes; for example, unisexual female ramets are advantageous in the first half of the flowering season and bloom then (minority sex hypothesis). That study, however, did not distinguish among the three pollination morphs of C. simplex. We investigated seasonal sex ratio changes and pollinator environments of the three morphs to verify and expand the minority sex hypothesis. We investigated flowering phenology, pollinator quantity and quality, seasonal population sex ratio dynamics, and stamen/ovule ratios in hermaphroditic flowers. We also examined the seasonal female reproductive success of hermaphroditic flowers, and the effect of male flower excision on fruit set by morph II hermaphroditic flowers. Morph I (mainly hermaphroditic and female ramets) had high pollinator quality and quantity. Fruit set of hermaphroditic ramets was high throughout the flowering season. Morph II (hermaphroditic and andromonoecious ramets) had low pollinator quality, and few pollinators visited near the beginning and end of the season. Removal of male flowers led to a pollen limitation. Morph III (hermaphroditic ramets and a high selfing rate) had very low pollinator abundance throughout the flowering season, and male and female phases largely overlapped. The scarcity of male flowers in morph I is likely a result of the high pollinator quantity and quality. The high fruit set suggests that no pollen limitation existed. The low pollinator quality and quantity of the morph II population caused it to suffer from pollen limitation and may explain the absence of unisexual female ramets in this morph. The high selfing rate of morph III may be due to the extremely low pollinator abundance. Theoretical studies have indicated that the optimal investment allocation to male and female functions depends on whether a pollen limitation exists. In C. simplex, the observed relationships between pollinator environment and reproductive systems are consistent with these theoretical models. [ABSTRACT FROM AUTHOR]

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 bumblebee‐visited 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 plant–pollinator 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. [ABSTRACT FROM AUTHOR]

Cimicifuga simplex (Ranunculaceae) has three genetically distinct pollination morphs. Here, we report that each of the three pollination morphs of C. simplex differs from the others with regard to sex expression and mating system: morph I consists mostly of ramets with hermaphroditic flowers and ramets with only female flowers, morph II consists of ramets with hermaphroditic flowers and ramets with hermaphroditic and male flowers, and morph III consists mostly of ramets with hermaphroditic flowers. A microsatellite analysis of seed DNA showed that morph III has a high self‐fertilization rate. Flowering season and flower visitor assemblages, which also differ among the three morphs, may influence the evolution and maintenance of the differences in sex expression and mating systems in the morphs. [ABSTRACT FROM AUTHOR]