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BACKGROUND: Rivea ornata, a rare species from the morning glory family, exhibits uncommon characteristics compared to other typical morning glories, including nocturnal flowers that fit the classic moth pollination syndrome. However, the accuracy of its predicted pollination syndrome and its mating system have never been assessed. Additionally, R. ornata flowers attract not only pollinators but also florivores, potentially reducing plant reproductive success. Therefore, this study examined two populations of R. ornata in Thailand and assessed traits related to pollinator attraction and reward, determined its mating system, identified floral visitors and effective pollinators, and investigated the effect of florivory on reproductive success. RESULTS: Rivea ornata is highly fertile but self-incompatible and an obligate outcrosser, rendering it highly dependent on pollinators. Lepidopterans, particularly nocturnal hawk moths, were found to account for a significant proportion of all visits and were the sole effective pollinators of this plant species, in correspondence with its predicted pollination syndrome. Surprisingly, florivory did not significantly reduce reproductive success. This phenomenon may be explained by the strategies employed by R. ornata, which align with the optimal defense hypothesis and functional trade-offs. Specifically, R. ornata appears to invest resources in defending key floral structures while, simultaneously, guard ants are conspicuously absent from flowers, resulting in some florivore damage to non-vital floral organs but ensuring that pollinators are not deterred by ants and thus maintaining high pollinator visitation rates. CONCLUSIONS: Our findings indicate that reproduction-related traits in R. ornata, including those involved in pollinator attraction and reward and florivore defense, are highly effective and work in concert to maximize plant reproductive success. Therefore, a main risk that R. ornata faces is the decline or disappearance of hawk moths and other lepidopterans given its extreme specialization and high dependence on pollinators, and conservation efforts should include habitat protection for both R. ornata and its pollinators.

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The tree fern Culcita macrocarpa, a threatened Iberian-Macaronesian endemism, represents the sole European species of the order Cyatheales. Considered a Tertiary relict of European Palaeotropical flora, its evolutionary history and genetic diversity, potentially influenced by presumed high clonal propagation, remain largely unknown. This study elucidates the phylogeographic history of C. macrocarpa, assessing the impact of vegetative reproduction on population dynamics and genetic variability. We provide genetic data from eight newly identified nuclear microsatellite loci and one plastid DNA region for 17 populations spanning the species' range, together with species distribution modeling data. Microsatellites reveal pervasive clonality in C. macrocarpa, which has varied among populations. We assess the impact of clonality on genetic diversity and evaluate how estimates of intra-population genetic diversity indices and genetic structuring are affected by the chosen definition of "individual" (focusing exclusively on genetically distinct individuals, genets, as opposed to considering all independent clonal replicates, ramets). We identify two main population groups, one in the northern Iberian Peninsula and the other in the Macaronesian archipelagos and southern Iberian Peninsula. Within each group, we found relict populations (in the Azores and the Cantabrian Cornice) as well as recent originated populations. This population structure suggests colonization dynamics in which recent populations originated from one or a few genets of relict populations and became established through intra-gametophytic self-fertilization and vegetative expansion. DAPC analysis facilitated the identification of alleles that most significantly contributed to the observed population structure. The current Andalusian populations appear to have originated from colonization events from the Azores and the Cantabrian Cornice. Our findings suggest that C. macrocarpa persisted through the Last Glacial Maximum in two refugia: the Azores and the Cantabrian Cornice. Colonization into new areas occurred presumably from these refuges, generating two large population groups with structured genetic diversity. This study underscores the significance of clonality in establishing new populations and shaping genetic structure.

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Pollinators are needed for the reproduction of Echites umbellatus, and only sphingid moths have mouthparts long enough to reach the nectar at the bottom of the species' long, twisted floral tube. Though plants produce many flowers over a period of several months, one observes very few fruits in nature. We asked: (1) Are plants self-compatible, or do they need pollen from another individual to set fruit and seed? (2) Are cross-pollinations between unrelated individuals more successful than crosses with relatives? (3) How does the relatedness of pollen and ovule parent plants affect fruit set, seed number, and seed quality? We investigated the breeding system of E. umbellatus by collecting fruits from seven sites, growing plants and performing hand pollinations over a period of several years, collecting and measuring fruits and counting seeds. Echites umbellatus is self-incompatible, though some individuals produce fruit by self-pollination. Cross-pollinations between unrelated individuals set the most fruit (59%), and those that were self-pollinated set the least (9%). Fruit set from cross-pollinations between related individuals was intermediate (32%). Although the number of seeds per fruit did not differ significantly among pollination treatments, fruits from self-pollinations had substantially fewer viable seeds than outcrossed fruits, with fruits from sibling crosses being intermediate. There were higher levels of self-compatibility in the fragment populations compared with plants from intact habitats. Self-incompatibility may explain why fruit set is low in this plant species; future investigation into the breakdown of self-incompatibility in smaller populations is warranted.

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Gradual pollen presentation is a plant reproductive mechanism to improve pollination efficiency and accuracy and promote outcrossing. Vaccinium corymbosum 'Bluecrop' has a typical gradual pollen presentation mechanism. 'Bluecrop' exhibits an inverted bell-shaped flower with a white coloration. By investigating the flower syndrome, pollination characteristics, pollination efficiency, and breeding system of 'Bluecrop', this study aims to explore the adaptive significance of these traits. The results showed 'Bluecrop' released pollen gradually through anther poricidal dehiscence. Among different pollinators, Apis mellifera and Bombus can pollinate effectively, and the mechanism of gradual pollen presentation significantly improved the efficiency of pollen transfer. This characteristic limits the amount of pollen removed by the pollinators and prolongs pollen presentation, thus attracting more pollinators and thereby increasing male fitness. The nectar secretion of 'Bluecrop' is gradual, with a large nectar production and a long phase of nectar secretion, enhance visitation frequencies and the chances of successful pollination. At the same time, campanulate corolla can protect pollen as well as nectar from waste due to environmental factors and other effects. The breeding system of 'Bluecrop' relies mainly on outcrossing because of its low affinity for self-fertilization and good interaction with pollinating insects. Thus, the special floral syndrome and the mechanism of secondary pollen presentation are significant in improving pollination efficiency and promoting the reproductive success of 'Bluecrop' by outcrossing. It can provide a certain theoretical basis for the future propagation breeding of 'Bluecrop'.

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Iris ruthenica Ker-Gawl. (Russian iris) is a perennial, clonal, herbaceous plant that is spread across the degraded mountain grasslands in northern Xinjiang. In this study, to explore the breeding system and the impact of slope orientation on the flowering phenology, pollination characteristics, and other aspects of I. ruthenica, we used a combination of field observations and controlled experiments to compare the population density, flowering phenology, floral characteristics, breeding system, and pollinator type and behavior of plants on different slope orientations. Vegetation coverage on the north (N), southwest (SW), and southeast (SE) slopes was 90%, 67%, and 53%, respectively. Differences in plant height and diameter were observed between the SE slope and the N and SW slopes, whereas the N and SW slopes were similar in these respects. The SE slope exhibited the earliest initial flowering time, followed by the SW and N slopes. The diameter of the corolla, distance between the stigma and anther, length of the anther and ovary, number of pollen grains, and number of ovules on the N slope were smaller than those on the SE and SW slopes, whereas those of the SE and SW slopes were similar. Artificial pollination experiments showed that neither bagging nor unbagging resulted in seed formation after emasculation for all slope orientations. The pollinating insects of I. ruthenica included Bombus sp., Amegilla leptocoma, Andrena sp., and Halictus sp.; the types and numbers of pollinating insects differed among slopes. In summary, on SE and SW slopes with high temperatures and sufficient sunlight, this species attracted pollinators and provided them with more opportunities to visit and pollinate by flowering early, with large numbers of blooms, and a longer flowering period and lifespan, ensuring successful reproduction. Under unfavorable conditions, such as insufficient pollinators and limited activity caused by the more stressful environmental conditions of the N slope (including low temperature and insufficient light), this species ensures a certain seed yield by increasing its self-compatibility.

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The genetic architecture of mating-type loci in lichen-forming fungi has been characterized in very few taxa. Despite the limited data, and in contrast to all other major fungal lineages, arrangements that have both mating-type alleles in a single haploid genome have been hypothesized to be absent from the largest lineage of lichen-forming fungi, the Lecanoromycetes. We report the discovery of both mating-type alleles from the haploid genomes of three species within this group. Our results demonstrate that Lecanoromycetes are not an outlier among Ascomycetes.

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Among flowering plants, self-incompatibility is considered the most efficient system for avoiding self-fertilization. However, many self-incompatible plants have also evolved floral mechanisms to reduce sexual conflict. In China, some studies of Bulbophyllum have been reported to be self-incompatible and no fruit sets. However, we have observed relatively high fruit sets in Bulbophyllum funingense. Therefore, we speculated that if B. funingense is also self-incompatible, and it might present a floral mechanism to avoid sexual conflict. Natural fruit sets, pollinia removal and deposition rates were determined and breeding system was tested in a hand-pollination experiment. The pollination process and visiting frequency of pollinators and their behavior after escape from access were observed and recorded. Floral traits associated with pollination and pollinator size were measured. B. funingense was completely self-incompatible, the fruit sets of cross-pollination in 2 years were all more than 70%, and the natural fruit sets for 2 years were 1.70 ± 4.31% and 6.63 ± 5.29%, respectively. B. funingense did not produce strong odor or nectar, but produced a kind of secretions from its labellum that attracted flies. Calliphora vicina (Calliphoridae) was its only effective pollinator. When C. vicina licked the secretions, they were stuck in the access for a long time. Thus, when they escaped from access, they almost always flew quickly away from the inflorescence removing pollinia most of the times. In B. funingense, a floral mechanism improves pollinia transfer efficiency, reduces pollinia waste, promotes pollination success, reduces the incidence of self-pollination, and avoids sexual conflict to a certain extent.

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Although Chaenomeles is widely used in horticulture, traditional Chinese medicine and landscape greening, insufficient research has hindered its breeding and seed selection. This study investigated the floral phenology, floral organ characteristics, palynology, and breeding systems of Chaenomeles speciosa (Sweet) Nakai. The floral characteristics of C. speciosa were observed both visually and stereoscopically. The microstructures of the flower organs were observed using scanning electron microscopy. Pollen stainability was determined using triphenyl tetrazolium chloride staining. Stigma receptivity was determined using the benzidine-H2O2 method and the post-artificial pollination pollen germination method. The breeding system was assessed based on the outcrossing index and pollen-ovule ratio. The flowers of C. speciosa were bisexual with a flowering period from March to April. The flowering periods of single flowers ranged from 8 to 19 d, and those of single plants lasted 18-20 d. The anthers were cylindrical, with the base attached to the filament, and were split longitudinally to release pollen. The flower had five styles, with a connate base. The ovaries had five carpels and five compartments. The inverted ovules were arranged in two rows on the placental axis. The stigma of C. speciosa was dry and had many papillary protrusions. In the early flowering stage (1-2 d of flowering), the pollen exhibited high stainability (up to 84.24%), but all stainability was lost at 7 d of flowering. Storage at - 20 °C effectively delayed pollen inactivation. The stigma receptivity of C. speciosa lasted for approximately 7 days, and the breeding system was classified as outcrossing with partial self-compatibility.

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The andromonoecy is an unusual sex expression in trees in which an individual plant bears both functionally staminate and hermaphrodite flowers on the inflorescences. This study aims to investigate the effect of crown layers on the floral biology and reproductive effort of Aesculus indica (Wall. ex Camb.) Hook. The results revealed that the peak period of anthesis was between 06:00 and 08:00 h of the day. Male flower production was predominantly higher as compared to the perfect flowers on the inflorescences. There was no significant variation between total pollen production in staminate and perfect flowers. Features like protogyny and inter-level asynchrony promote xenogamy; however, intra-level asynchrony results in geitonogamy. Controlled pollination treatments revealed the existence of self-incompatibility in flowers. Pollination syndromes in flowers support ambophily. A trend of consistent improvement in reproductive success from lower canopy layers to upper crown layers in the analyzed trees was recorded. The crown layers have a significant impact on flower production, fruit, and seed set. An increase in male flower production due to the increment in the crown is a mechanism of reproductive assurance as a pollen donor and pollinator recipient and also due to the differential cost of expenditure of reproduction in crown layers. Andromonoecy in A. indica promotes self-incompatibility, and there was a tapering trend of reproductive success in the crown layers.

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Orchidaceae, one of the most numerous families in the world's flora, have evolved various pollination strategies to favour cross-pollination, such as deceptive pollination and pollinarium reconfiguration. Among the terrestrial orchids of the Mediterranean, only species belonging to the genus Serapias show a strategy defined as shelter imitation. The floral elements form a tubular structure that insects use during their resting phases. The purpose of this article was to clarify the mechanisms that guarantee pollination with particular attention to the morphological interactions between orchids and pollinators and whether pollinaria reconfiguration is necessary in the promotion of cross-pollination in Serapias. Breeding system experiments and hand-pollination treatments indicated that Serapias was highly self-compatible, shows low value of natural fruit set and is pollinator limited. Time-lapse photos showed that the pollinarium had no refolding of the stipe or caudicle after its removal from the flower. The morphology of the flower determined the attack of the pollinarium on the occiput/vertex of insect. When the insect left the flower, the pollinarium was unable to encounter the stigma. When the insect made a second visit to another flower, the pollen masses of the first pollinarium ended up on the stigma and at the same time, the insect picked up a second pollinarium. Our observations and analyses suggested that morphological interactions between flower and pollinator are crucial to the success of pollination and to prevent self-pollination and thus that pollinarium reconfiguration is unnecessary in shelter deceptive orchids, such as Serapias species, for the promotion of cross-pollination. Serapias represent a case of interactions between plant and pollinator; the formation of the tubular shape of the flower is an essential preadaptation for the development of resting site mimicry originating exclusively in Serapias among Mediterranean orchids.

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BACKGROUND AND AIMS: Chromosome evolution leads to hybrid dysfunction and recombination patterns and has thus been proposed as a major driver of diversification in all branches of the tree of life, including flowering plants. In this study we used the genus Linum (flax species) to evaluate the effects of chromosomal evolution on diversification rates and on traits that are important for sexual reproduction. Linum is a useful study group because it has considerable reproductive polymorphism (heterostyly) and chromosomal variation (n = 6-36) and a complex pattern of biogeographical distribution. METHODS: We tested several traditional hypotheses of chromosomal evolution. We analysed changes in chromosome number across the phylogenetic tree (ChromEvol model) in combination with diversification rates (ChromoSSE model), biogeographical distribution, heterostyly and habit (ChromePlus model). KEY RESULTS: Chromosome number evolved across the Linum phylogeny from an estimated ancestral chromosome number of n = 9. While there were few apparent incidences of cladogenesis through chromosome evolution, we inferred up to five chromosomal speciation events. Chromosome evolution was not related to heterostyly but did show significant relationships with habit and geographical range. Polyploidy was negatively correlated with perennial habit, as expected from the relative commonness of perennial woodiness and absence of perennial clonality in the genus. The colonization of new areas was linked to genome rearrangements (polyploidy and dysploidy), which could be associated with speciation events during the colonization process. CONCLUSIONS: Chromosome evolution is a key trait in some clades of the Linum phylogeny. Chromosome evolution directly impacts speciation and indirectly influences biogeographical processes and important plant traits.

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Studying the signatures of evolution can help to understand genetic processes. Here, we demonstrate how the existence of balancing selection can be used to identify the breeding systems of fungi from genomic data. The breeding systems of fungi are controlled by self-incompatibility loci that determine mating types between potential mating partners, resulting in strong balancing selection at the loci. Within the fungal phylum Basidiomycota, two such self-incompatibility loci, namely HD MAT locus and P/R MAT locus, control mating types of gametes. Loss of function at one or both MAT loci results in different breeding systems and relaxes the MAT locus from balancing selection. By investigating the signatures of balancing selection at MAT loci, one can infer a species' breeding system without culture-based studies. Nevertheless, the extreme sequence divergence among MAT alleles imposes challenges for retrieving full variants from both alleles when using the conventional read-mapping method. Therefore, we employed a combination of read-mapping and local de novo assembly to construct haplotypes of HD MAT alleles from genomes in suilloid fungi (genera Suillus and Rhizopogon). Genealogy and pairwise divergence of HD MAT alleles showed that the origins of mating types predate the split between these two closely related genera. High sequence divergence, trans-specific polymorphism, and the deeply diverging genealogy confirm the long-term functionality and multiallelic status of HD MAT locus in suilloid fungi. This work highlights a genomics approach to studying breeding systems regardless of the culturability of organisms based on the interplay between evolution and genetics.

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PREMISE: Divergence of floral morphology and breeding systems are often expected to be linked to angiosperm diversification and environmental niche divergence. However, available evidence for such relationships is not generalizable due to different taxonomic, geographical and time scales. The Palearctic genus Helianthemum shows the highest diversity of the family Cistaceae in terms of breeding systems, floral traits, and environmental conditions as a result of three recent evolutionary radiations since the Late Miocene. Here, we investigated the tempo and mode of evolution of floral morphology in the genus and its link with species diversification and environmental niche divergence. METHODS: We quantified 18 floral traits from 83 taxa and applied phylogenetic comparative methods using a robust phylogenetic framework based on genotyping-by-sequencing data. RESULTS: We found three different floral morphologies, putatively related to three different breeding systems: type I, characterized by small flowers without herkogamy and low pollen to ovule ratio; type II, represented by large flowers with approach herkogamy and intermediate pollen to ovule ratio; and type III, featured by small flowers with reverse herkogamy and the highest pollen to ovule ratio. Each morphology has been highly conserved across each radiation and has evolved independently of species diversification and ecological niche divergence. CONCLUSIONS: The combined results of trait, niche, and species diversification ultimately recovered a pattern of potentially non-adaptive radiations in Helianthemum and highlight the idea that evolutionary radiations can be decoupled from floral morphology evolution even in lineages that diversified in heterogeneous environments as the Mediterranean Basin.

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Mating system shifts from outcrossing to selfing are frequent in plant evolution. Relative to outcrossing, selfing is associated with reduced parental conflict over seed provisioning, which may result in postzygotic, asymmetric, reproductive isolation in crosses between populations of different mating systems. To test the hypothesis that post-pollination reproductive isolation between populations increases with increasing differences in mating system and predicted parental conflict, we performed a crossing experiment involving all combinations of three self-compatible populations (with low outcrossing rates), and three self-incompatible populations (with high outcrossing rates) of the arctic-alpine herb Arabis alpina, assessing fitness-related seed and plant traits of the progeny. Predicted levels of parental conflict ("genome strength") were quantified based on strength of self-incompatibility and estimates of outcrossing rates. Crosses between self-compatible and self-incompatible populations yielded very small seeds of low viability, resulting in strong reproductive isolation. In 14 of 15 reciprocal between-population crosses, seeds were heavier when the paternal plant had the stronger genome, and seed mass differences between cross directions increased with an increased difference in parental conflict. Overall, our results suggest that, when sufficiently large, differences in mating system and hence in expected parental conflict may result in strong post-pollination reproductive barriers contributing to speciation.

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Research on diploid hybrid potato has made fast advances in recent years. In this review we give an overview of the most recent and relevant research outcomes. We define different components needed for a complete hybrid program: inbred line development, hybrid evaluation, cropping systems and variety registration. For each of these components the important research results are discussed and the outcomes and issues that merit further study are identified. We connect fundamental and applied research to application in a breeding program, based on the experiences at the breeding company Solynta. In the concluding remarks, we set hybrid breeding in a societal perspective, and we identify bottlenecks that need to be overcome to allow successful adoption of hybrid potato.

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PREMISE: Pollinator decline, by reducing seed production, is predicted to strengthen natural selection on floral traits. However, the effect of pollinator decline on gender dimorphic species (such as gynodioecious species, where plants produce female or hermaphrodite flowers) may differ between the sex morphs: if pollinator decline reduces the seed production of females more than hermaphrodites, then it should also have a larger effect on selection on floral traits in females than in hermaphrodites. METHODS: To simulate pollinator decline, we experimentally reduced pollinator access to female and hermaphrodite Lobelia siphilitica plants. We compared the seed production of plants in the reduced pollination treatment to plants that were exposed to ambient pollination conditions. Within each treatment, we also measured directional selection on four floral traits of females and hermaphrodites. RESULTS: Experimentally reducing pollination decreased seed production of both females and hermaphrodites by ~21%. Reducing pollination also strengthened selection on floral traits, but this effect was not larger in females than in hermaphrodites. Instead, reducing pollination intensified selection for taller inflorescences in hermaphrodites, but did not intensify selection on any floral trait in females. CONCLUSIONS: Our results suggest that pollinator decline will not have a larger effect on either seed production or selection on floral traits of female plants. As such, any effect of pollinator decline on seed production may be similar for gender dimorphic and monomorphic species. However, the potential for floral traits of females (and thus of gender dimorphic species) to evolve in response to pollinator decline may be limited.

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Both intrinsic and extrinsic forces work together to shape connectivity and genetic variation in populations across the landscape. Here we explored how geography, breeding system traits, and environmental factors influence the population genetic patterns of Triodanis perfoliata, a widespread mix-mating annual plant in the contiguous US. By integrating population genomic data with spatial analyses and modeling the relationship between a breeding system and genetic diversity, we illustrate the complex ways in which these forces shape genetic variation. Specifically, we used 4705 single nucleotide polymorphisms to assess genetic diversity, structure, and evolutionary history among 18 populations. Populations with more obligately selfing flowers harbored less genetic diversity (π: R 2 = .63, p = .01, n = 9 populations), and we found significant population structuring (F ST = 0.48). Both geographic isolation and environmental factors played significant roles in predicting the observed genetic diversity: we found that corridors of suitable environments appear to facilitate gene flow between populations, and that environmental resistance is correlated with increased genetic distance between populations. Last, we integrated our genetic results with species distribution modeling to assess likely patterns of connectivity among our study populations. Our landscape and evolutionary genetic results suggest that T. perfoliata experienced a complex demographic and evolutionary history, particularly in the center of its distribution. As such, there is no singular mechanism driving this species' evolution. Together, our analyses support the hypothesis that the breeding system, geography, and environmental variables shape the patterns of diversity and connectivity of T. perfoliata in the US.

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The reproductive system is essential for the structuring and transmission of genetic diversity. Understanding the reproductive biology of threatened endemic species is considered to be a crucial element for the implementation of effective conservation strategies. Given the lack of information and the insufficient state of knowledge on the reproductive system of Anacyclus pyrethrum L., a threatened medicinal species endemic to Morocco, we are the first to study the reproductive biology of two varieties of Anacyclus pyrethrum L.: Anacyclus pyrethrum var. pyrethrum (L.) Link and Anacyclus pyrethrum var. depressus (Ball.) Maire. The reproductive biology of the two varieties was examined in detail by studying the development of the inflorescence, phenology of flowering, breeding system, pollinators, production, and seed dispersal. The experimental results described in this work suggest that Anacyclus pyrethrum L. is a gynomonic species, with a mixed autogamy-allogamy reproductive regime with a high predominance of allogamy. It appears to be partially self-incompatible, with allogamy rates for Anacyclus pyrethrum var. depressus (Ball.) Maire and Anacyclus pyrethrum var. pyrethrum (L.) Link of 78.70% and 79.01%, respectively. It depends on pollination vectors to produce a large number of seeds. This study on the breeding system of Anacyclus pyrethrum L. provides a tool for developing management strategies and adequate conservation measures.

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New infestations of the Formosan subterranean termite, Coptotermes formosanus Shiraki (Blattodea: Rhinotermitidae), were discovered in southern California, namely in Rancho Santa Fe and La Mesa (San Diego County) and Highland Park (Los Angeles County) in 2021. We investigated whether these new infestations were related to the previous infestations in La Mesa (2018) and Canyon Lake, Riverside County (2020). We used two mitochondrial genes (COI and COII) and seven polymorphic microsatellite markers to infer the genetic relationship between southern California colonies and their breeding systems. The samples collected from seven localities belonged to five colonies (inter-colony distances ranged from ~160 m to 185 km, with an average of 97 km). Of these five colonies, two were simple families, and three were extended families. Structure analyses of microsatellite genotypes grouped the termite samples into three distinct genetic clusters, suggesting at least three independent introduction events in southern California.

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BACKGROUND: Floral morphs are characterized differentiations in reciprocal positions of sexual organs and ancillary floral traits in heterostylous plants. However, it remains unclear how differential floral morphs ensure reproductive success between morphs using the same pollinator. RESULTS: Measurements of floral traits in white-flowered Tirpitzia sinensis with long corolla tubes indicated that it is typically distylous, long-styled (L-) morph producing more but smaller pollen grains per flower than short-styled (S-) morph. Both morphs secreted more nectar volume at night than in the day and the sugar composition was rich in sucrose, potentially adaptive to pollination by hawkmoths (Macroglossum spp.) which were active at dusk. A bumblebee species functioned as the nectar robber in both morphs and a honeybee as the pollen feeder in the S-morph. The L-morph secreted more nectar volume but relatively lower sucrose/hexose ratio than the S-morph. Floral visitation rate by hawkmoths was higher but its pollination efficiency was lower in the S-morph than the L-morph. Hand pollination treatments indicated self-incompatibility in T. sinensis and seed set of open-pollinated flowers did not differ between morphs. CONCLUSIONS: Our findings suggest that the two morphs differ with respect to traits relevant to pollination. The L-morph, with its exserted stigma, has more pollen grains per anther and a greater volume of nectar, which may prolong the foraging time and increase the pollination efficiency of hawkmoths. The S-morph has a higher sucrose/hexose ratio in its nectar which can be more attractive to hawkmoths and increase the visit rates. Ancillary polymorphic floral traits between two morphs are adaptive to hawkmoth and ensure reproductive success in distylous plant T. sinensis.

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