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Premise Barriers at different reproductive stages contribute to reproductive isolation. Self‐incompatibility (SI) systems that prevent self‐pollination could also act to control interspecific ... pollination and contribute to reproductive isolation, preventing hybridization. Here we evaluated whether SI contributes to reproductive isolation among four co‐occurring Opuntia species that flower at similar times and may hybridize with each other. Methods We assessed whether Opuntia cantabrigiensis, O. robusta, O. streptacantha, and O. tomentosa, were self‐compatible and formed hybrid seeds in five manipulation treatments to achieve self‐pollination, intraspecific cross‐pollination, open pollination (control), interspecific crosses or apomixis, then recorded flowering phenology and synchrony. Results All species flowered in the spring with a degree of synchrony, so that two pairs of species were predisposed to interspecific pollination (O. cantabrigiensis with O. robusta, O. streptacantha with O. tomentosa). All species had distinct reproductive systems: Opuntia cantabrigiensis is self‐incompatible and did not produce hybrid seeds as an interspecific pollen recipient; O. robusta is a dioecious species, which formed a low proportion of hybrid seeds; O. streptacantha and O. tomentosa are self‐compatible and produced hybrid seeds. Conclusions Opuntia cantabrigiensis had a strong pollen–pistil barrier, likely due to its self‐incompatibility. Opuntia robusta, the dioecious species, is an obligate outcrosser and probably partially lost its ability to prevent interspecific pollen germination. Given that the self‐compatible species can set hybrid seeds, we conclude that pollen–pistil interaction and high flowering synchrony represent weak barriers; whether reproductive isolation occurs later in their life cycle (e.g., germination or seedling survival) needs to be determined. more

Restricted seed dispersal frequently leads to fine‐scale spatial genetic structure (i.e., FSGS) within plant populations. Depending on its spatial extent and the mobility of pollinators, this ... inflated kinship at the immediate neighbourhood can critically impoverish pollen quality. Despite the common occurrence of positive FSGS within plant populations, our knowledge regarding the role of long‐distance pollination preventing reproductive failure is still limited. Using microsatellite markers, we examined the existence of positive FSGS in two low‐density populations of the tree Pyrus bourgaeana. We also designed controlled crosses among trees differing in their kinship to investigate the effects of increased local kinship on plant reproduction. We used six pollination treatments and fully monitored fruit production, fruit and seed weight, proportion of mature seeds per fruit, and seed germination. Our results revealed positive FSGS in both study populations and lower fruit initiation in flowers pollinated with pollen from highly‐genetically related individuals within the neighbourhood, with this trend intensifying as the fruit development progressed. Besides, open‐pollinated flowers exhibited lower performance compared to those pollinated by distant pollen donors, suggesting intense qualitative pollen limitation in natural populations. We found positive fine‐scale spatial genetic structure is translated into impoverished pollen quality from nearby pollen donors which negatively impacts the reproductive success of trees in low‐density populations. Under this scenario of intrapopulation genetic rescue by distant pollen donors, the relevance of highly‐mobile pollinators for connecting spatially and genetically distant patches of trees may be crucial to safeguarding population recruitment. more

Abstract When related species are distributed in sympatric populations, hybridization may occur. Likewise, one or more of these species may have arisen through historical hybridization between taxa. ... Here, we aim to elucidate the occurrence of hybridization among three Dyckia spp. (Bromeliaceae) from southern Brazil. We used seven nuclear and six plastid microsatellite loci to assess patterns of genetic diversity, population structure and hybridization in the three species. Furthermore, we performed manual crosses between species to test compatibility and fertility. The results showed that Dyckia julianae has an intermediate molecular profile, low gene flow occurs between Dyckia hebdingii and Dyckia choristaminea and higher gene flow occurs between D. julianae and the other two species. Plastid microsatellites identified 12 haplotypes that are shared among the species. The manual crosses between D. julianae and the other two species produced viable seeds, but no crosses between D. hebdingii and D. choristaminea generated fruits. Our data suggest that the reproductive barrier between D. julianae and the other two species is permeable. Further investigation into the hybrid origin hypothesis of D. julianae should be undertaken, as well as the mechanisms involved in reproductive isolation between D. hebdingii and D. choristaminea. more

Main conclusion Self-incompatibility studies have revealed a potential use of Tunisian apple resources for crop improvement and modern breeding programs and a likely correlation between the pollen ... tube growth and flowering period. ss Apples Malus domestica. Borkh exhibit an S -RNase-based gametophytic self-incompatibility (GSI) system. Four primer combinations were used to S -genotype eighteen Tunisian local apple accessions and twelve introduced accessions that served as references. Within the Tunisian local accessions, S 2, S 3, S 7, and S 28 S -alleles were the most frequent and were assigned to 14 S -genotypes; among them, S 7 S 28, S 3 S 7, S 2 S 5, and S 2 S 3 were the most abundant. PCA plot showed that population structuring was affected by the S -alleles frequencies and revealed a modern origin of the Tunisian varieties rather than being ancient ones. Nonetheless, the results obtained with 17 SSR markers showed a separate grouping of local Tunisian accessions that calls into question the hypothesis discussed. Pollination experiments showed that the pollen started to germinate within 24 h of pollination but 48 h after pollination in the “El Fessi” accession. The first pollen tubes arrived in the styles within 36 h of pollination in two early flowering accessions known as “Arbi” and “Bokri”, and after 72 h of pollination in late flowering “El Fessi” and 48 h after pollination in remaining accessions. The first pollen tube arrests were observed in accessions “Arbi” and “Bokri” within 84 h of pollination, within 108 h of pollination in “El Fessi” and within 108 h of pollination in remaining accessions. In the apple accession called “Boutabgaya,” the pollen tubes reached the base of the style within 120 h of pollination without being aborted. Nevertheless, the self-compatible nature of “Boutabgaya” needs more studies to be confirmed. However, our results revealed the malfunction of the female component of the GSI in this accession. To conclude, this work paved the path for further studies to enhance the insight (i) into the relation between the flowering period and the pollen tube growth, (ii) self-compatible nature of “Boutabgaya”, and (iii) the origin of the Tunisian apple. more

先島諸島と台湾南部に産するハテルマギリ（アカネ科）の花形態とその繁殖特性を明らかにするために，本種の雄蕊と雌蕊の開花時における高さ，花粉染色性とサイズ，授粉実験による二型花間の和合性，野外における結果率の調査等を行った．本種の葯や柱頭の高さは花や個体間の変異が著しく，その頻度分布において二型花柱性植物によく見られる二山分布を示さず2群に分かれなかったが，葯と柱頭の高さの差による頻度分布では明瞭に2群に別れ，また柱頭と葯の高さにおいても，一方は柱頭が葯より高い位置にある長花柱花，他方は柱頭が葯より低い位置にある短花柱花という二型性を示したが，柱頭と葯の高さは二型花間で相互に対応せず，ずれた状態にあった．しかし，二型の個体はいずれの野外集団においてもほぼ1:1の割合で存在し，また二型花はいずれも花粉稔性をもち，野外で同等の結果・結実率を示していた．さらに授粉実験の結果は，本種が自家・同型花不和合性をもち，結実には二型花間の相互交配が必要であることを示した．これらの結果は，本種が形態・機能的に二型花柱性ではあるが，その二型性は柱頭と葯の高さが相互に対応せず，ずれた状態の特異な二型花柱性であることを示している．柱頭と葯の高さが二型花間で対応せずに相互交配が担保されていることは非常に特異である．これにはスズメガ類による送粉が関与している可能性もあり，今後送粉様式に着目した調査を進めて行くことを考えている．

Although West Indian Cherry (WIC) trees have abundant flowering, specimens of this species have low fructification rates, potentially associated with the dependence of these plants on pollinators for ... cross‐pollination and fruit production. We quantified fructification rates and assessed the market value of pollination services by conducting an experiment with six treatments, including manual and open pollination, pollinator exclusion treatment, and open pollination with blue and yellow attractants. The investigation occurred at two sampling periods (November–December 2015 and January–February 2016) in a commercial orchard of WIC in Brazil. Despite the six different treatments in the two sampling periods, the fructification rate only differed in open pollination treatments with colour attractants, increasing the fructification rate between 160% (for blue‐coloured attractants) and 240% (for yellow‐coloured attractants). Considering that yield is directly affected by the increase in the fructification rate, the yield might be enhanced by up to 70 ton/ha by the coloured attractants. Economically speaking, this result means an approximate 130% increase in the earnings for farmers and maybe transferable to other crops contributing to food production and recognizing the importance of biodiversity and associated ecosystem services. more

Inbreeding depression is a reduction of fitness in the progeny of closely related individuals and its effects are assigned to selfing or biparental inbreeding. Vriesea gigantea is a self‐compatible ... bromeliad species distributed in the Brazilian Atlantic rainforest and habitat destruction and fragmentation and collection have decreased the natural populations. We aim to describe the occurrence of inbreeding depression (δ) in three natural populations of V. gigantea and to correlate this phenomenon with previous studies of fertility, genetic diversity, population genetic structure, gene flow, mating system and seed dispersal in this species. Fifty‐four adult plants were sampled and 108 flowers were used for pollination treatments (selfing, outcrossing and control). For adult plants, we analysed plant and inflorescence height, flower numbers and seed set. In the progenies, evaluated parameters included seed germination and seedling survival rate. The results indicated low to moderate levels of inbreeding depression in V. gigantea (δ = 0.02 to 0.39), in agreement with molecular data from a previous study. Vriesea gigantea populations tolerate some degree of inbreeding, which is consistent with previous results on fertility, mating system, genetic diversity and gene flow. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 169, 312–319. more

ミズガンピPemphis acidula J. R. Forst. & G. Forst. ... は，アフリカ東部から太平洋地域にかけての海岸に広く分布するミソハギ科の常緑低木で，日本では奄美諸島以南の琉球列島に広く分布する．これまでアフリカ〜インド・マレー半島地域集団で進められた研究により，この種はその多くの集団で長花柱花と短花柱花の二型性が確認され（一部の集団では等花柱性），それぞれの花は高さが異なる二種類の葯をつけるという通常の二型花柱性にはみられない特徴をもつことが報告された．それゆえ，この種の二型花柱性は本来三型花柱性であったものから，中花柱花が消失することで長花柱花と短花柱花の二型になったと推定されてきた．しかし，それを論じるための繁殖特性についての調査はいまだ充分とは言い難く，また分布域全体を通じた調査も，特に日本を含む東アジア地域での調査はあまり行われていない．そこで，この種の形態・繁殖特性，さらには有効な送粉昆虫を理解するために，日本・台湾の4 集団を対象にして，花形態の変異の解析や授粉実験，送粉昆虫の調査等を行った．その結果，これらの集団はいずれも他の地域での報告と一致する二型花柱性を示すことが確認された．花粉サイズは，長花柱花よりも短花柱花の葯の方が有意に大きいが，同一花の高さが異なる葯間には有意な差は認められなかった．また，人工授粉実験により二型花は自家・同型花不和合性を示すこともわかった．三型花から二型花柱性に変化したとすると，中位の位置の葯にとっては本来の送粉器官（中位の柱頭）が失われてしまったことになるが，短花柱花の中位の葯は長花柱花の柱頭と，長花柱花の中位の葯は短花柱花の柱頭との間で和合性を示し，葯の高さが違ってもすでに二型性の状態にあることが確認された．さらに，送粉昆虫として西表島集団では短舌のハナバチ類，狩りバチ類がもっと有効であることが確認された． more

Pemphis acidula J. R. Forst. & G. Forst. (Lythraceae) has been speculated to show distyly derived from tristyly by loss of the mid (M)-styled morph. To understand morphological and reproductive ... natures and pollinators effective for pollination we examined floral variation, fruit and seed production by pollination experiments, and flower visitors in four natural populations of P. acidula occurring in Taiwan and Japan. The populations examined were commonly distylous with long (L)- and short (S)-styled morphs, but each morph had anthers arranged at two different levels, as in some other populations of the species reported earlier. Pollen grains were significantly larger in the S-styled morph than in the L-styled one, but there was no significant difference in pollen size between the two anthers from different levels. Furthermore, artificial pollination experiments indicated that the two morphs exhibited self and intramorphic incompatibility, and the middle-level anther had the same compatibility as the other-level anther of the same morph. These results suggest that the pollen size and the compatibility system have a distylous nature in the examined populations, despite the fact that the anthers are arranged in two different levels in each morph. Short-tongued bees and aculeate wasps frequently visited the flowers for sucking nectar and touched their mouthpart to the stigma and the anthers, suggesting that they may be the most efficient pollinators for completing crosspollination between the two morphs at the Iriomote population of the species. more

The polyploid species Herbertia lahue (Molina) Goldblatt is widespread in the grassland areas of southern America. In this study, genotypic and phenotypic variations among hexaploids and octoploids ... from H. lahue were assessed based on quantitative floral traits and ISSR markers. Additionally, gynoecium and breeding systems were analysed through anatomical analysis and hand-pollination experiments. Cytotypes are self-compatible, and the anatomy of the embryo sac remains similar in hexaploids and octoploids. AMOVA indicates that hexaploid populations are less genetically variable than octoploids (respectively 4 and 22 %, P < 0.001), thus the largest source of genetic variation for H. lahue lies among populations (82 %, P < 0.001), probably a combined effect of selfing, changes in population size, and local adaptation. Genetic variation between cytotypes was significant (16 %, P < 0.001), though unclear segregation among cytotypes was discovered through PCoA. A Mantel test indicated no relationship between geographic and genetic distances (r = 0.04; P = 0.37), possibly as a result of the combined effect of the recurrent origin of polyploids, gene flow restricted by selfing, and poor capacity for seed dispersal. In terms of floral measurements, eight measures of perigonium, androecium, and gynoecium varied significantly between cytotypes, though no clear grouping was defined by PCA. Presumably, complex variation in floral characters across cytotypes may result in the absence of distinct grouping by PCA. The combined use of ISSR markers and morphological characters revealed a complex relationship between H. lahue cytotypes shaped by both intrinsic and extrinsic factors. more