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Mountains are reservoirs for a tremendous biodiversity which was fostered by a suite of factors acting in concert throughout evolutionary times. These factors can be climatic, geological, or biotic, but the way they combine through time to generate diversity remains unknown. Here, we investigate these factors as correlates of diversification of three closely related sections of Gentiana in the European Alpine System. Based upon phylogenetic approaches coupled with divergence dating and ancestral state reconstructions, we attempted to identify the role of bedrock preferences, chromosome numbers coupled with relative genome sizes estimates, as well as morphological features through time. We also investigated extant climatic preferences using a heavily curated set of occurrence records individually selected for superior precision, and quantified rates of climatic niche evolution in each section. We found that a number of phylogenetic incongruences derail the identification of correlates of diversification, yet a number of patterns persist regardless of the topology considered. All the studied correlates are likely to have contributed to the diversification of Gentiana in Europe, however, their respective importance varied through time and across clades. Chromosomal variation and divergence of climatic preferences appear to correlate with diversification throughout the evolution of European Gentiana (Oligocene to present), whereas shifts in bedrock preferences appear to have been more defining during recent diversification (Pliocene). Overall, a complex interaction among climatic, geological and biotic attributes appear to have supported the diversification of Gentiana across the mountains of Europe, which based upon phylogenetic as well as other evidence, was probably also bolstered by hybridization.

The genus Laoennea (Streptaxoidea, Diapheridae) was erected by Páll-Gergely, 2020. The type species, Laoennea carychioides Páll-Gergely, A. Reischütz & Maassen, 2020 is so far only known from the type locality cave in Laos. Herein, we describe a second species, Laoennea renouardisp. nov., from a nearby cave in the same karst region of Vientiane Province.

The Hengduan Mountains are one of the most species-rich mountainous areas in the world. The origin and evolution of such a remarkable biodiversity are likely to be associated with geological or climatic dynamics, as well as taxon-specific biotic processes (e.g., hybridization, polyploidization, etc.). Here, we investigate the mechanisms fostering the diversification of the endemic Himalopsyche martynovi complex, a poorly known group of aquatic insects. We used multiple allelic datasets generated from 691 AHE loci to reconstruct species and RaxML phylogenetic trees. We selected the most reliable phylogenetic tree to perform network and gene flow analyses. The phylogenetic reconstructions and network analysis identified three clades, including H. epikur, H. martynovi sensu stricto and H. cf. martynovi. Himalopsyche martynovi sensu stricto and H. cf. martynovi present an intermediate morphology between H. epikur and H. viteceki, the closest known relative to the H. martynovi-complex. The gene flow analysis revealed extensive gene flow among these lineages. Our results suggest that H. viteceki and H. epikur are likely to have contributed to the evolution of H. martynovi sensu stricto and H. cf. martynovi via gene flow, and thus, our study provides insights in the diversification process of a lesser-known ecological group, and hints at the potential role of gene flow in the emergence of biological novelty in the Hengduan Mountains.

SummaryEcological differentiation can drive speciation but it is unclear how the genetic architecture of habitat-dependent fitness contributes to lineage divergence. We investigated the genetic architecture of cumulative flowering, a fitness component, in second-generation hybrids between Silene dioica and S. latifolia transplanted into the natural habitat of each species.We used reduced-representation sequencing and Bayesian Sparse Linear Mixed Models (BSLMMs) to analyze the genetic control of cumulative flowering in each habitat.Our results point to a polygenic architecture of cumulative flowering. Allelic effects were mostly beneficial or deleterious in one habitat and neutral in the other. The direction of allelic effects was associated with allele frequency differences between the species: positive-effect alleles were often derived from the native species, whereas negative-effect alleles, at other loci, tended to originate from the non-native species.We conclude that ecological differentiation is governed and maintained by many loci with small, conditionally neutral effects. Conditional neutrality may result from differences in selection targets in the two habitats and provides hidden variation upon which selection can act. Polygenic architectures of adaptive differentiation are expected to be transient during lineage divergence and may therefore be unrelated to high genetic differentiation at the underlying loci.

BackgroundThe yield of commercially harvested “vegetable caterpillar” Ophiocordyceps sinensis has dramatically plummeted in the last few decades, while market demand has increased. Besides controlling the obvious overexploitation of this species, understanding how edaphic factors influence this system may improve the chances of successful cultivation and thus support the conservation of O. sinensis in the wild. Our study investigates how the presence/absence and the quality of O. sinensis may be linked to a series of edaphic factors pertinent to its microhabitat, including enzyme activity, nutrients, moisture, pH and nematode population. In order to provide a preliminary hypothesis on the relationships among edaphic factors and their influence on O. sinensis, we performed a principal component analysis and structural equation modelling despite limited replication. ResultsSoil samples containing O. sinensis were more moist and contained a higher concentration of nutrients and enzyme activity than control samples collected nearby, where the species was absent. Preliminary analyses indicated that enzyme activity may be crucial and appeared to be affected by a number of other soil factors. We found that O. sinensis would occupy microhabitats with a relatively higher soil fertility and a more persistent enzyme activity, where the values of total nitrogen and catalase are especially important. Otherwise, with the exception of organic matter and enzyme activity, mean values did not suggest any other factors potentially corresponding to a better quality of O. sinensis.ConclusionsBased on these preliminary findings and a further literature review, we formulated the first integrative hypothesis (network of interactions) on how soil factors may influence each other and O. sinensis. Finally, we indicate how this hypothesis may be tested in the future, in order to increase the chances for successful cultivation and thus promote the conservation and sustainable harvesting of O. sinensis.

The structure and sequence of plastid genomes is highly conserved across most land plants, except for a minority of lineages that show gene loss and genome degradation. Understanding the early stages of plastome degradation may provide crucial insights into the repeatability and predictability of genomic evolutionary trends. We investigated these trends in subtribe Gentianinae of the Gentianaceae, which encompasses ca. 450 species distributed around the world, particularly in alpine and subalpine environments. We sequenced, assembled, and annotated the plastomes of 41 species, representing all six genera in subtribe Gentianinae and all main sections of the species‐rich genus Gentiana L. We reconstructed the phylogeny, estimated divergence times, investigated the phylogenetic distribution of putative gene losses, and related these to substitution rate shifts and species’ habitats. We obtained a strongly supported topology consistent with earlier studies, with all six genera in Gentianinae recovered as monophyletic and all main sections of Gentiana having full support. While closely related species have very similar plastomes in terms of size and structure, independent gene losses, particularly of the ndh complex, have occurred in multiple clades across the phylogeny. Gene loss was usually associated with a shift in the boundaries of the small single‐copy and inverted repeat regions. Substitution rates were variable between clades, with evidence for both elevated and decelerated rate shifts. Independent lineage‐specific loss of ndh genes occurred at a wide range of times, from Eocene to Pliocene. Our study illustrates that diverse degradation patterns shape the evolution of the plastid in this species‐rich plant group., This study traces plastome evolution of all main lineages of the species‐rich group Gentianinae, and shows lineage‐specific patterns of plastid degradation and shifts in substitution rates.

Two heterobranch species, Stylocheilus striatus (Quoy & Gaimard, 1825) (Anaspidea, Aplysiidae) and Pleurobranchusforskalii Rüppel & Leuckart, 1828 (Nudipleura, Pleurobranchidae) are reported for the first time for BazarutoIsland, Mozambique. Swarming behavior of Stylocheilus striatus, which was previously described for other localities,was also observed for the first time in the Bazaruto Archipelago. The sea slugs were photographed in situ and identifiedin sync with their species descriptions, photographic databases and the current literature.

The origin and evolution of alpine biota are not yet fully understood, particularly in the vast Asian mountain regions. In addition, in these regions, most studies have concentrated on taxa occurring in areas benefitting from relatively generous rainfall from the summer monsoon. In this study, we collected a large number of Oxytropis species throughout their distribution range, and investigated the taxonomy and evolution of this diverse legume genus, which also occurs in mountainous areas prone to drought. Using nuclear (ITS) and plastid (trnL‐F) markers, we reconstructed phylogenetic relationships within Oxytropis, conducting maximum parsimony, fasttree‐like, maximum likelihood, Bayesian, and BEAST analyses. We also used Anchored Hybrid Enrichment (AHE) to test the power of this method to resolve relationships among a small subset of Oxytropis species. For AHE, we sampled eight species and obtained 527 low‐copy and orthologous nuclear loci. We show that the taxonomy of this genus that radiated explosively in Asian mountains will remain recalcitrant based on conventional molecular methods. Because of a severe lack of resolution, none of the available taxonomic treatments for Oxytropis could either be confirmed or refuted based upon ITS and trnL‐F. Nevertheless, we confirm the status of several species, and identify morphological or genetic particularities for some groups of species. The AHE approach yielded a highly supported phylogenetic tree, suggesting that increased taxon sampling coupled with AHE methods promise advances in the study of the taxonomy and evolution of Oxytropis, thus providing further analytical opportunities, such as diversification rate and biogeographical analyses.

Aim Geologically dynamic areas often harbour remarkable levels of biodiversity. Among other factors, mountain building is assumed to be a precondition for species radiation, and yet, the potential role of immigration as a source of biodiversity prior to radiation is often neglected. Here, we studied the biogeographical history of the large genus Saxifraga to unravel the role played by the Qinghai-Tibet Plateau (QTP) for the diversification of this genus and to understand factors that have led to the establishment of high biodiversity in and around this region. Location QTP and surrounding mountain ranges and worldwide distribution range of Saxifraga. Methods Using a total of 420 taxa (321 ingroup taxa) comprising more than 60% of extant Saxifraga species, we studied the evolutionary history of Saxifraga by performing phylogenetic analyses (maximum likelihood and Bayesian inference on nuclear ITS and plastid trnL–trnF, matK sequences), divergence time estimation (using uncorrelated log-normal clock models and four fossil constraints in beast) and ancestral range estimation (using BioGeoBEARS). Results Saxifraga originated in North America around 74 (64–83) Ma, dispersed to South America and northern Asia during its early diversification and colonized Europe and the QTP region by the Late Eocene. The QTP region was colonized several times independently, followed in some lineages by rapid radiations, temporally coinciding with recent uplifts of the Hengduan Mountains at the southeastern fringe of the QTP. Subsequently, several lineages dispersed out of Tibet. Main conclusions Immigration, recent rapid radiation and lineage persistence were all important processes for the establishment of a rich species stock of Saxifraga in the QTP region. Because floristic exchanges between the neighbouring areas and the QTP region were bi-directional, the spatio-temporal evolution of Saxifraga contrasts with the ‘out of QTP’ pattern, which has often been assumed for northern temperate plants.

Aim We investigated the historical biogeography and diversification of Gentiana L. (Gentianaceae). Our study depicts the origin and dispersal routes of this alpine genus, and the role of the uplift of the Qinghai–Tibet Plateau (QTP) and past climate changes as triggers for its diversification. Location Tibeto-Himalayan region and world-wide mountain habitats. Methods Our sampling represents more than 50% of the extant Gentiana species, including all sections across their entire geographical ranges. We investigated the evolutionary history of Gentiana using phylogenetic reconstructions (maximum likelihood and Bayesian inference) of ITS, atpB–rbcL and trnL–trnF sequences, as well as molecular dating with beast. We tested two approaches of ancestral area reconstructions (DEC, DIVA) in BioGeoBEARS and investigated diversification rates using BAMM. Results The common ancestor of Gentiana and subtribe Gentianinae lived in the QTP region at around 34 (25–45) million years ago (Ma), and 40 (29–52) Ma respectively. From the surroundings of the QTP, Gentiana lineages dispersed to eastern China, Taiwan, Europe, North and South America, Australia and New Guinea, from mid-Miocene onward (c. 15 Ma–present), with only one older dispersal event to Europe (c. 37–21 Ma). Diversification rates gradually increased over time, and two switches of diversification rates were identified in Gentianinae (c. 7 Ma, simultaneously in the Pneumonanthe/Cruciata lineage and in Tripterospermum). Main conclusions Gentiana existed in the QTP region throughout most of its uplift history following the India-Asia collision. This region acted as the primary source area for dispersals to many areas of the world. Because steady increase in diversification rates coincides with the extension of the QTP, we argue that the museum theory rather than the explosive radiation theory prevails for gentians in this region, although rare shifts of diversification rates are associated with niche shifts across the alpine/subalpine ecotone.

Two new varieties of Kuepferia pringlei D. Maity & S. K. Dey from north Sikkim (eastern Himalaya) are described, illustrated, and compared with closely related taxa of similar morphology. Details on its habitat, phenology and conservation status are provided. These previously undescribed varieties are most similar to, but distinct from, typical K. pringlei D. Maity & S. K. Dey, known from the eastern Himalaya. Both new taxa are compared with K. leucantha (Harry Sm. ex T.N. Ho & S.W. Liu) Adr.Favre.

New species arise through the evolution of reproductive barriers between formerly interbreeding lineages. Yet, comprehensive assessments of potential reproductive barriers, which are needed to make inferences on processes driving speciation, are only available for a limited number of systems. In this study, we estimated individual and cumulative strengths of seven prezygotic and six postzygotic reproductive barriers between the recently diverged taxa Silene dioica (L.) Clairv. and S. latifolia Poiret using both published and new data. A combination of multiple partial reproductive barriers resulted in near‐complete reproductive isolation between S. dioica and S. latifolia, consistent with earlier estimates of gene flow between the taxa. Extrinsic barriers associated with adaptive ecological divergence were most important, while intrinsic postzygotic barriers had moderate individual strength but contributed only little to total reproductive isolation. These findings are in line with ecological divergence as driver of speciation. We further found extensive variation in extrinsic reproductive isolation, ranging from sites with very strong selection against migrants and hybrids to intermediate sites where substantial hybridization is possible. This situation may allow for, or even promote, heterogeneous genetic divergence.

AIM: We investigated the biogeography of the subtropical mountain genus Tripterospermum Blume (Gentianaceae), disjunctly distributed at the southern fringe of the Qinghai–Tibetan Plateau (QTP) and other mountain systems within the biodiversity hotspots of Southeast Asia. This study reveals dispersal routes among these areas. LOCATION: East China, Indochina, Japan, the Philippines, southeastern fringe of the Qinghai–Tibetan Plateau (southern Himalaya and Hengduanshan), Taiwan, Wallacea. METHODS: The evolutionary history of Tripterospermum was studied using the phylogenetic reconstructions (Maximum Likelihood and Bayesian Inference using ITS, atpB–rbcL and trnL–trnF), molecular dating (using BEAST with a relaxed clock model and fossil constraints), and two approaches of ancestral area reconstructions (DEC, S‐DIVA). Our sampling design included 82% of the extant species of subtropical Gentianinae (Tripterospermum, Metagentiana, Sinogentiana and Crawfurdia) as ingroup, and Kuepferia, Gentiana and other Gentianaceae genera as outgroups. RESULTS: Subtropical Gentianinae originated at the southeastern fringe of the QTP (the southern Himalaya and Hengduanshan) between 16 and 35 million years ago (Ma). With a crown age estimated to be 2.7–8.8 million years (Myr), Tripterospermum originated at the southeastern fringe of the QTP, from where it dispersed to East China, Indochina, Sundaland, Taiwan, Japan and Wallacea. MAIN CONCLUSIONS: For Tripterospermum, the southern Himalaya and the Hengduanshan have acted as a source area for the colonization of East and Southeast Asia. This study depicts dispersal routes among the biodiversity hotspots neighbouring the QTP and those located on Sundaland and Wallacea. Mountain plants seem to have colonized Wallacea using a northern route via Taiwan rather than a more southern route via Sundaland. The latter route has previously been recorded for many lowland lineages. Because Tripterospermum species‐producing berries have dispersed more often across geographical barriers than those producing capsules, we hypothesize that avian transportation of berry‐like fruits might have facilitated their dispersal.

Five years ago, the Panamanian evolutionary lineage (EL) C12 was uncovered along with four other ELs in an integrative phylogenetic investigation of worldwide Carychiidae. Since EL C12 lacked shell material post-molecular analysis to serve as a museum voucher, it remained undescribed. Now, after recent collection efforts of C12 and the congener, Carychiumzarzaae Jochum & Weigand, 2017 at their original Panamanian sites, C12 is morphologically described and formally assigned the name, Carychiumpanamaense Jochum, sp. n. In sync with recent taxonomic treatment of the genus, computed tomography (CT) is used in this work to differentiate shells of C.panamaensesp. n. from geographically-proximal, Caribbean, North and Central American congeners. Recent material of topotypic Carychiumjardineanum (Chitty, 1853) and undamaged C.zarzaae were additionally CT-scanned and assessed in the comparative analyses.

Three new species of the genus Carychium O.F. Müller, 1773, Carychium hardiei Jochum & Weigand, sp. n., Carychium belizeense Jochum & Weigand, sp. n. and Carychium zarzaae Jochum & Weigand, sp. n. are described from the Southeastern United States, Belize and Panama, respectively. In two consecutive molecular phylogenetic studies of worldwide members of Carychiidae, the North and Central American morphospecies Carychium mexicanum Pilsbry, 1891 and Carychium costaricanum E. von Martens, 1898 were found to consist of several evolutionary lineages. Although the related lineages were found to be molecularly distinct from the two nominal species, the consequential morphological and taxonomic assessment of these lineages is still lacking. In the present paper, the shells of these uncovered Carychium lineages are assessed by comparing them with those of related species, using computer tomography for the first time for this genus. The interior diagnostic characters are emphasized, such as columellar configuration in conjunction with the columellar lamella and their relationship in context of the entire shell. These taxa are morphologically described and formally assigned their own names.

Species differences are maintained by the cumulative effect of factors that reduce gene flow between divergent lineages. In this issue, Karrenberg et al. quantify multiple genetic and environmental barriers to gene exchange between two closely related plant species and find that adaptation to divergent environments has the greatest effect on reproductive isolation.

Subtribe Gentianinae, encompassing Gentiana, Tripterospermum, Metagentiana and Crawfurdia, represents one of the most species-rich clades of Gentianaceae. Only a few taxonomic uncertainties have remained at generic level in subtribe Gentianinae: the inclusion of Gentiana sect. Otophora in Gentiana, and the polyphyletic nature of Metagentiana. In both cases, data were lacking in earlier studies to resolve ambiguities and provide the baseline for a solid taxonomic treatment of these lineages. For the present study, we increased the number of species sequenced for Gentiana sect. Otophora and Metagentiana, using a combination of nuclear (ITS) and plastid (trnL-F, atpB-rbcL) markers. We reconstructed phylogenetic relationships in Gentianinae conducting maximum likelihood and Bayesian analyses. Our results show that Gentiana sect. Otophora is monophyletic and more closely related to Metagentiana than to Gentiana. We suggest excluding Gentiana sect. Otophora from Gentiana and elevating this group to the rank of genus described here under the name Kuepferia. Metagentiana is monophyletic when excluding two species, M striata and M souliei, here described as the new genus Sinogentiana.

This paper presents descriptions and illustrations for two new species of Gentianaceae, Tripterospermum maculatum from Sichuan Province (China) and T. tanatorajanense from Sulawesi (Indonesia). Based on literature search, Tripterospermum maculatum is morphologically close to T. pingbianense and T. lanceolatum, and T. tanatorajanense resembles T. luzonense and T. alutaceifolium. To test if the new species differ from their morphologically most similar species, we measured various traits on herbarium specimens and performed a principal component analysis (PCA). This analysis showed that the new species differ from similar species in gross morphology for several diagnostic traits. Tripterospermum maculatum differs from T. pingbianense and T. lanceolatum by having calyx lobes longer than calyx tubes, a whitish-yellow corolla maculated with purple dots, and a gynophore shorter than the ovary. Tripterospermum tanatorajanense is distinct from T. luzonense by having a narrowly winged calyx. It differs fr...

Summary 1. Hybridization is common in natural plant populations. Trait expression and ecological performance of hybrids determine the consequences of hybridization such as the degree and direction of gene flow or the generation of phenotypic novelty. 2. We investigated responses to shade and drought stress in crosses within the naturally hybridizing campions Silene dioica and S. latifolia and reciprocal crosses between them. We collected data on fitness proxies and on leaf and root traits in a 2-year greenhouse experiment. 3. Responses to drought stress did not differ between cross types. Shade stress, in contrast, led to a reduced flowering incidence in S. dioica but not in S. latifolia. Rapid flowering under stress conditions in S. latifolia could be an adaptation to disturbance in its habitat, whereas a delay of reproduction might be adaptive in the more predictable environment of S. dioica. 4. Hybrids exhibited intermediate, parental-like and transgressive trait expression. Both hybrid cross types were similar to S. latifolia in terms of biomass production possibly because of dominance of S. latifolia alleles or heterosis. Hybrids further had a strongly reduced flowering incidence under shade stress as did S. dioica, suggesting dominance of S. dioica alleles for flower induction. Under shade stress, both hybrid cross types produced much larger leaves than either of the two species suggesting that epigenetic interactions are disturbed. Reciprocal hybrids did not differ in fitness; however, maternal effects were observed for root cross-sectional area and mass per male flower, possibly supporting asymmetric gene flow in natural populations. 5. Synthesis. Silene latifolia and S. dioica responded to stress with differences in life history rather than in growth. Our results further suggest that different modes of gene action are responsible for the specific combination of intermediate, parental-like and transgressive traits observed in first-generation hybrids that may limit their performance and thus gene flow between the species.

The subtribe Gentianinae comprises ca. 425 species, most of them within the well-studied genus Gentiana and mainly distributed over the Eurasian continent. Phylogenetic relationships between Gentiana and its closest relatives, the climbing gentians (Crawfurdia, Tripterospermum) and the new genus Metagentiana, remain unclear. All three genera were recently found to be polyphyletic, possibly because of poor sampling of Tripterospermum and Crawfurdia. Highest diversity of Gentianinae occurs in the western Himalaya, but the absence of uncontroversial fossil evidence limits our understanding of its biogeography. In the present study, we generated ITS and atpB-rbcL sequences for 19 species of Tripterospermum, 9 of Crawfurdia and 11 of Metagentiana, together representing about 60 percent of the species diversity of these genera. Our results show that only Metagentiana is polyphyletic and divided into three monophyletic entities. No unambiguous synapomorphies were associated with the three Metagentiana entities. Different combinations of three approximate calibration points were used to generate three divergence time estimation scenarios. Although dating hypotheses were mostly inconsistent, they concurred in associating radiation of Gentiana to an orogenic phase of the Himalaya between 15 and 10 million years ago. Our study illustrates the conceptual difficulties in addressing the time frame of diversification in a group lacking sufficient fossil number and quality.

Ecological differentiation is a major contributor to the generation and maintenance of biological diversity. We investigated habitat differentiation between and within sites in the fully cross-fertile and hybridizing Silene dioica and S. latifolia using amplified fragment length polymorphisms (AFLP) profiles and corresponding vegetation releves around individual plants. Nineteen study sites in the Swiss Alps included pure sites and contact sites (both taxa present within 30 m). In pure sites and at contact sites, the two taxa showed consistently differentiated AFLP banding patterns across regions but few discriminating bands. This indicates that although the two taxa are weakly differentiated, current introgression has not led to genome-wide admixture. Only three putative early generation hybrids were detected at contact sites. The habitats of the two taxa differed between pure sites with S. dioica occurring in moister, colder, and less-disturbed sites than S. latifolia. However, asymmetric habitat overlap was evident within contact sites found in intermediate conditions that were more similar to S. latifolia sites. This situation might favor introgression from S. dioica into S. latifolia. Evidence for habitat–genotype associations within contact sites was weak making habitat-mediated selection against intermediate phenotypes of hybrids unlikely in the contact sites investigated. We suggest that other reproductive barriers together with dispersal limitation contribute to the rarity of early generation hybrids.

Summary In order to investigate the role of differential adaptation for the evolution of reproductive barriers, we conducted a multi-site transplant experiment with the dioecious sister species Silene dioica and S. latifolia and their hybrids. Crosses within species as well as reciprocal first-generation (F1) and second-generation (F2) interspecific hybrids were transplanted into six sites, three within each species' habitat. Survival and flowering were recorded over 4 yr. At all transplant sites, the local species outperformed the foreign species, reciprocal F1 hybrids performed intermediately and F2 hybrids underperformed in comparison to F1 hybrids (hybrid breakdown). Females generally had slightly higher cumulative fitness than males in both within- and between-species crosses and we thus found little evidence for Haldane's rule acting on field performance. The strength of selection against F1 and F2 hybrids as well as hybrid breakdown increased with increasing strength of habitat adaptation (i.e. the relative fitness difference between the local and the foreign species) across sites. Our results suggest that differential habitat adaptation led to ecologically dependent post-zygotic reproductive barriers and drives divergence and speciation in this Silene system.

Specialization in plant–insect interactions is an important driver of evolutionary divergence; yet, plant traits mediating such interactions are poorly understood. In this study, we investigated how flower color and floral scent are related to seed predation by a seed-eating pollinator. We used field-transplanted recombinant F2 hybrids between Silene latifolia and S. dioica that are the preferred and alternative hosts of the moth Hadena bicruris and crosses within these species for comparison. We scored seed predation and flower color and analyzed floral scent. Pinker S. dioica-like flowers and emission of α-pinene decreased the odds of seed predation while emission of benzyl acetate and 6-methyl-5-hepten-2-one increased the odds of seed predation. Emission of these compounds did not differ significantly between the two Silene species. Our results suggest that flower color plays an important role in the specific interaction of H. bicruris with its preferred host S. latifolia. The compounds α-pinene, benzyl acetate and 6-methyl-5-hepten-2-one could represent non-specific deterrents and attractants to ovipositing moths. Alternatively, emission of these compounds could be related to herbivory or pathogen attack and act as a signal for host quality. This would weaken the predictability of the plant's costs and benefits of the interaction and act to maintain an imperfect degree of specialization., PLoS ONE, 9 (6), ISSN:1932-6203