Dimensional study of prostate cancer using stereological tools.

This study analyzes the dimensional changes of the glands from prostate cancer by applying stereology to estimate the variations in volume, length, surface, and cellular densities of tumor acini. Normal and tumor acini were visualized using immunohistochemistry for cytokeratin18. On immunostained sections, parameters related to the dimensions and cell population of prostate acini were measured. The immunohistochemical expression of proliferative cell nuclear antigen was also measured to correlate the quantitative changes estimated with the proliferative activity of the epithelium. The average cell volume in normal and tumor epithelium was estimated using the method of the nucleator. The relative size of the acini was similar in the carcinoma compared with the normal prostate. Within the acini, the fraction of acinar volume occupied by the epithelium was significantly higher in cancer than in the nontumor prostate. Conversely, the glandular lumen of the cancer acini is lower than in the normal acini. The significant increase of acinar length density in the carcinoma indicates that the glandular tree's growth in the carcinoma is higher and with more branches than in the case of nonneoplastic glands. The basal surface density is higher in the carcinoma than in the controls. The number of epithelial cells per unit length of acini was significantly decreased in the neoplastic glands. This "dilution" of the cell population along the cancer acinus can be explained by the significant increase in the tumor cell's mean cell volume.

Protective role of vitamin E in testicular development of mice exposed to valproic acid.

Valproic acid (VPA) is a teratogenic antiepileptic, causing alterations in oxidative stress in prenatal development, being altered the development of the male reproductive system. The purpose of this study was to determine the protective effect of vitamin E (VE) on the testicular development in embryos, foetuses and pubertal mice exposed to VPA, VPA+VE and only VE. Sixty pregnant adult female mice were used, to which they were administered 600 mg/kg of VPA (VPA groups), 600 mg/kg of VPA and 200 IU of VE (VPA+VE groups), 200 IU VE (VE groups) and 0.3 ml of 0.9% physiological solution (control groups), showing at 12.5 days post-coital (dpc), 17.5 dpc and 6 weeks postnatal testicular development, and proliferative and apoptotic indices. The groups treated with VPA presented a smaller testicular volume, with greater interstitial space and a delay in the conformation of the testicular cords, shorter lengths and diameters of the germinal epithelium, a smaller number of germline and somatic cells, an increase in cells apoptotic and less proliferation, with significant differences. VE-treated groups behaved similarly to controls. In conclusion, VE reduces the effects caused by VPA throughout testicular development, from embryonic stages, continuing until pubertal stages.

Notch and Bmp signaling pathways act coordinately during the formation of the proepicardium.

BACKGROUND: The epicardium is the outer mesothelial layer of the heart. It encloses the myocardium and plays key roles in heart development and regeneration. It derives from the proepicardium (PE), cell clusters that appear in the dorsal pericardium (DP) close to the atrioventricular canal and the venous pole of the heart, and are released into the pericardial cavity. PE cells are advected around the beating heart until they attach to the myocardium. Bmp and Notch signaling influence PE formation, but it is unclear how both signaling pathways interact during this process in the zebrafish. RESULTS: Here, we show that the developing PE is influenced by Notch signaling derived from the endothelium. Overexpression of the intracellular receptor of notch in the endothelium enhances bmp expression, increases the number of pSmad1/5 positive cells in the DP and PE, and enhances PE formation. On the contrary, pharmacological inhibition of Notch1 impairs PE formation. bmp2b overexpression can rescue loss of PE formation in the presence of a Notch1 inhibitor, but Notch gain-of-function could not recover PE formation in the absence of Bmp signaling. CONCLUSIONS: Endothelial Notch signaling activates bmp expression in the heart tube, which in turn induces PE cluster formation from the DP layer.

Chasing the ghost of infection past: identifying thresholds of change during the COVID-19 infection in Spain.

One of the largest nationwide bursts of the first COVID-19 outbreak occurred in Spain, where infection expanded in densely populated areas through March 2020. We analyse the cumulative growth curves of reported cases and deaths in all Spain and two highly populated regions, Madrid and Catalonia, identifying changes and sudden shifts in their exponential growth rate through segmented Poisson regressions. We associate these breakpoints with a timeline of key events and containment measures, and data on policy stringency and citizen mobility. Results were largely consistent for infections and deaths in all territories, showing four major shifts involving 19-71% reductions in growth rates originating from infections before 3 March and on 5-8, 10-12 and 14-18 March, but no identifiable effect of the strengthened lockdown of 29-30 March. Changes in stringency and mobility were only associated to the latter two shifts, evidencing an early deceleration in COVID-19 spread associated to personal hygiene and social distancing recommendations, followed by a stronger decrease when lockdown was enforced, leading to the contention of the outbreak by mid-April. This highlights the importance of combining public health communication strategies and hard confinement measures to contain epidemics.

Selective logging in tropical forests decreases the robustness of liana-tree interaction networks to the loss of host tree species.

Selective logging is one of the major drivers of tropical forest degradation, causing important shifts in species composition. Whether such changes modify interactions between species and the networks in which they are embedded remain fundamental questions to assess the 'health' and ecosystem functionality of logged forests. We focus on interactions between lianas and their tree hosts within primary and selectively logged forests in the biodiversity hotspot of Malaysian Borneo. We found that lianas were more abundant, had higher species richness, and different species compositions in logged than in primary forests. Logged forests showed heavier liana loads disparately affecting slow-growing tree species, which could exacerbate the loss of timber value and carbon storage already associated with logging. Moreover, simulation scenarios of host tree local species loss indicated that logging might decrease the robustness of liana-tree interaction networks if heavily infested trees (i.e. the most connected ones) were more likely to disappear. This effect is partially mitigated in the short term by the colonization of host trees by a greater diversity of liana species within logged forests, yet this might not compensate for the loss of preferred tree hosts in the long term. As a consequence, species interaction networks may show a lagged response to disturbance, which may trigger sudden collapses in species richness and ecosystem function in response to additional disturbances, representing a new type of 'extinction debt'.

Flower-visitor selection on floral integration in three contrasting populations of Lonicera implexa.

PREMISE OF THE STUDY: Geographic differences in flower visitor assemblages might lead to among-population differences in the magnitude and pattern of floral integration. However, the role of current pollinator visitation in shaping the magnitude and pattern of floral trait correlations is still controversial. METHODS: We used individual-level data on floral morphology, flower visitation, and fitness to assess if floral integration (at flower and floral-module level) and the covariance structure of floral traits varied among three populations of Lonicera implexa differing in the importance of long-tongue (hawk moths) and short-tongue (bees and small beetles) pollinators; and to assess whether this variation was related to the selection pressures exerted by flower visitors. KEY RESULTS: Short-tongue pollinators preferentially visited plants with floral traits that enhanced flower accessibility; consequently, there was directional selection for accessibility (integration at floral-module level) in the populations where they dominated or codominated. In the population with both short- and long-tongue pollinators, disruptive selection on corolla width and directional selection against whole-flower integration was also found. Dominance by long-tongue pollinators (hawk moths) resulted in disruptive selection on whole-flower integration. Overall, the conflicting selection pressures that were found matched among-population differences in covariance structure: populations with short-tongue pollinators showed correlations between corolla-tube width and other floral traits that were absent in the population pollinated primarily by hawk moths. CONCLUSIONS: Conflicting selection on floral integration mediated by floral visitors can occur even in nearby populations of a species with restricted floral morphology.

Disentangling the roles of diversity resistance and priority effects in community assembly.

The assembly of many biological communities is constrained by the resistance exerted by resident species to immigration (biotic resistance). Two important mechanisms contribute to the generation of biotic resistance: diversity resistance and priority effects. These mechanisms have been explored through theoretical models and laboratory experiments, but the importance of their interplay in the assembly of natural communities remains untested. We used a mesocosm experiment with communities of aquatic plants and zooplankton assembled from natural propagule banks to test whether and how diversity resistance, mediated by the diversity of the resident community, and priority effects, mediated by the timing of immigrants' arrival, affect the establishment of immigrant species and community diversity. In plant communities, immigration success decreased with increasing resident-species richness (diversity resistance) and arrival time (priority effects). Further, diversity resistance was stronger in communities colonized later in the season, indicating that these mechanisms interacted to reinforce biotic resistance. This interaction ultimately determined species richness and beta-diversity in plant communities. For zooplankton, in contrast, neither the diversity of resident communities nor the time of arrival affected the establishment of immigrant species. In these communities, beta-diversity was explained by species sorting, namely biotic effects mediated by plant assemblages. Our results show that the progressive buildup of communities generates an interaction between diversity resistance and priority effects that eventually determines community diversity, unless species sorting mediated by environmental filtering supersedes the effect of biotic resistance. Therefore, disentangling the mechanisms underlying biotic resistance contributes to understand how species diversity is ultimately determined.

Optimal methods for fitting probability distributions to propagule retention time in studies of zoochorous dispersal.

BACKGROUND: Propagule retention time is a key factor in determining propagule dispersal distance and the shape of "seed shadows". Propagules dispersed by animal vectors are either ingested and retained in the gut until defecation or attached externally to the body until detachment. Retention time is a continuous variable, but it is commonly measured at discrete time points, according to pre-established sampling time-intervals. Although parametric continuous distributions have been widely fitted to these interval-censored data, the performance of different fitting methods has not been evaluated. To investigate the performance of five different fitting methods, we fitted parametric probability distributions to typical discretized retention-time data with known distribution using as data-points either the lower, mid or upper bounds of sampling intervals, as well as the cumulative distribution of observed values (using either maximum likelihood or non-linear least squares for parameter estimation); then compared the estimated and original distributions to assess the accuracy of each method. We also assessed the robustness of these methods to variations in the sampling procedure (sample size and length of sampling time-intervals). RESULTS: Fittings to the cumulative distribution performed better for all types of parametric distributions (lognormal, gamma and Weibull distributions) and were more robust to variations in sample size and sampling time-intervals. These estimated distributions had negligible deviations of up to 0.045 in cumulative probability of retention times (according to the Kolmogorov-Smirnov statistic) in relation to original distributions from which propagule retention time was simulated, supporting the overall accuracy of this fitting method. In contrast, fitting the sampling-interval bounds resulted in greater deviations that ranged from 0.058 to 0.273 in cumulative probability of retention times, which may introduce considerable biases in parameter estimates. CONCLUSIONS: We recommend the use of cumulative probability to fit parametric probability distributions to propagule retention time, specifically using maximum likelihood for parameter estimation. Furthermore, the experimental design for an optimal characterization of unimodal propagule retention time should contemplate at least 500 recovered propagules and sampling time-intervals not larger than the time peak of propagule retrieval, except in the tail of the distribution where broader sampling time-intervals may also produce accurate fits.

Meta-analysis of the effects of forest fragmentation on interspecific interactions.

Forest fragmentation dramatically alters species persistence and distribution and affects many ecological interactions among species. Recent studies suggest that mutualisms, such as pollination and seed dispersal, are more sensitive to the negative effects of forest fragmentation than antagonisms, such as predation or herbivory. We applied meta-analytical techniques to evaluate this hypothesis and quantified the relative contributions of different components of the fragmentation process (decreases in fragment size, edge effects, increased isolation, and habitat degradation) to the overall effect. The effects of fragmentation on mutualisms were primarily driven by habitat degradation, edge effects, and fragment isolation, and, as predicted, they were consistently more negative on mutualisms than on antagonisms. For the most studied interaction type, seed dispersal, only certain components of fragmentation had significant (edge effects) or marginally significant (fragment size) effects. Seed size modulated the effect of fragmentation: species with large seeds showed stronger negative impacts of fragmentation via reduced dispersal rates. Our results reveal that different components of the habitat fragmentation process have varying impacts on key mutualisms. We also conclude that antagonistic interactions have been understudied in fragmented landscapes, most of the research has concentrated on particular types of mutualistic interactions such as seed dispersal, and that available studies of interspecific interactions have a strong geographical bias (arising mostly from studies carried out in Brazil, Chile, and the United States).

Allometric scaling of long-distance seed dispersal by migratory birds.

Migratory birds are often suggested to be important vectors for long-distance dispersal (LDD) of plant and animal propagules. The scale of such dispersal events (hundreds to thousands of kilometers) can influence landscape-level biological processes and species distributions. However, the few vector species studied and the lack of proper integration of their migratory movement in models of LDD has precluded the study of their potential as long-distance biotic dispersers. By means of a mechanistic model parameterized with empirical data, we first investigated the properties of seed dispersal curves generated by migratory birds and then analyzed the effect of bird size on model parameters and consequent seed dispersal patterns. Seed dispersal curves showed in most cases large and heavy tails, resulting in relatively frequent LDD (up to 3.5% of dispersal distances longer than 100 km). Bird size mediated trade-offs between bird movement and seed retention time that, in turn, determined seed dispersal patterns and the potential of each bird species as an LDD vector. Our modeling framework builds on a mechanistic understanding of seed dispersal by migratory birds and may thus be a useful tool to estimate the scale and frequency of bird-mediated, large-scale transport of native, invasive, and pathogenic organisms.

Landscape heterogeneity increases the stability of wild ungulate populations facing climatic variability in Mediterranean ecosystems.

Mediterranean environments are characterized by strong intra- and inter-annual fluctuations in plant primary production, which are likely to regulate the carrying capacity and density-dependent responses of ungulate populations. These effects may, however, vary across spatial and temporal scales. Habitat heterogeneity, particularly when associated to differentiated phenological responses, may allow wild ungulates to mitigate temporal fluctuations in plant production by using different resources along the year. In this work, we use a 15-years dataset (including remote-sensing data on vegetation distribution, phenology and production, as well as ungulate population counts) to assess how temporal variability in plant primary production and livestock abundance influence the population dynamics of two wild ungulates: native red deer, Cervus elaphus, and introduced fallow deer, Dama dama. Results show that temporal alternation in the phenological cycles of the four different vegetation types increased plant production, thus food availability for ungulates, within each year. Furthermore, complementarity in the responses of different vegetation types to variations in the amount and timing of rainfall increased the predictability of food availability across different years. This complementarity effect was further increased by the contrasting responses of ungulate populations to variation in the production of different vegetation types. Furthermore, domestic ungulates had positive effects on wild ungulate density at low to intermediate abundances, but high livestock densities decreased ungulate density and constrained the stability of the plant-ungulate system in response to the impact of climatic variation, particularly under climate change. Our findings deepen the knowledge on vegetation-ungulate interactions in Mediterranean areas, potentially contributing to develop better management strategies of ungulate populations and adapt them to ongoing climate change.

Effects of matrix characteristics and interpatch distance on functional connectivity in fragmented temperate rainforests.

The connectivity of remnant patches of habitat may affect the persistence of species in fragmented landscapes. We evaluated the effects of the structural connectivity of forest patches (i.e., distance between patches) and matrix class (land-cover type) on the functional connectivity of 3 bird species (the White-crested Elaenia [Elaenia albiceps], the Green-backed Firecrown Hummingbird [Sephanoides sephaniodes], and the Austral Thrush [Turdus falklandii]). We measured functional connectivity as the rate at which each species crossed from one patch to another. We also evaluated whether greater functional connectivity translated into greater ecological connectivity (dispersal of fruit and pollen) by comparing among forest patches fruit set of a plant pollinated by hummingbirds and abundance of seedlings and adults of 2 plants with bird- and wind-dispersed seeds. Interpatch distance was strongly associated with functional connectivity, but its effect was not independent of matrix class. For one of the bird-dispersed plants, greater functional connectivity for White-crested Elaenias and Austral Thrushes (both frugivores) was associated with higher densities of this plant. The lack of a similar association for the wind-dispersed species suggests this effect is linked to the dispersal vector. The abundance of the hummingbird-pollinated species was not related to the presence of hummingbirds. Interpatch distance and matrix class affect animal movement in fragmented landscapes and may have a cascading effect on the distribution of some animal-dispersed species. On the basis of our results, we believe effort should be invested in optimizing patch configuration and modifying the matrix so as to mitigate the effects of patch isolation in fragmented landscapes.

COVID-19 effective reproduction number dropped during Spain's nationwide dropdown, then spiked at lower-incidence regions.

COVID-19 pandemic has rapidly spread worldwide. Spain has suffered one of the largest nationwide bursts, particularly in the highly populated areas of Madrid and Barcelona (two of the five largest conurbations in Europe). We used segmented regression analyses to identify shifts in the evolution of the effective reproduction number (Rt) reported for 16 Spanish administrative regions. We associate these breaking points with a timeline of key containment measures taken by national and regional governments, applying time lags for the time from contagion to case detection, with their associated errors. Results show an early decrease of Rt that preceded the nationwide lockdown; a generalized, sharp decrease in Rt associated with such lockdown; a low impact of the strengthened lockdown, with a flattening of Rt evolution in high-incidence regions, and even increases in Rt at low-incidence regions; and an increase in Rt associated to the relaxation of the lockdown measures in ten regions. These results evidence the importance of generalized lockdown measures to contain COVID-19 spread, and the limited effect of the subsequent application of a stricter lockdown (restrictions to all non-essential economic activities). Most importantly, they highlight the importance of maintaining strong social distancing measures and strengthening public health control during lockdown de-escalation.

Valproic acid during pregnancy decrease the number of spermatogenic cells and testicular volume in the offspring of mice: Stereological quantification.

Valproic acid (VPA) is a drug used to treat epilepsy, bipolar disorders and headaches. As a secondary effect, this antiepileptic drug can cause a decrease in androgens and gonadotropins, and dose-dependent testicular defects, such as reduction of testicular weights, sperm motility and degeneration of the seminiferous tubules. In offspring exposed to VPA, its effects have not been evaluated, so the study aimed to determine the morphological effects of the use of VPA along testicular development in mice. 30 adult female BALB/c mice were crossed and divided by age, with embryos of 12.5 days post coitum (dpc), fetuses of 17.5 dpc and male mice 6 weeks postnatal. In each case, the pregnant mouse received 600 mg/kg of VPA, making up the VPA groups, or 0.3 mL of 0.9% physiological solution for the control groups, from the beginning to the end of the pregnancy, orally.t. A morpho-quantitative analysis was carried out on the gonadal development of the male offspring. In the groups treated with VPA, at all ages studied they had lower testicular volume. At 12.5 dpc, they showed less testicular development in the form of sex cords, with fewer gonocytes and somatic cells. At 17.5 dpc, they presented greater interstitial space, fewer spermatogonial, sustentacular Sertoli, peritubular and interstitial Leydig cells. At 6 weeks postnatal, they presented fewer spermatogonia, pachytene spermatocytes, elongated spermatids, sustentacular Sertoli and interstitial Leydig cells, with statistically significant differences. In conclusion, prenatal exposure to VPA causes histopathological alterations in the offspring of mice in testicular development, from the embryonic stage to 6 weeks postnatal.

[Hypersensitivity to ß-lactam antibiotics: algorithms of management and desensitization as a vital therapeutic alternative]. / Hipersensibilidad a antibióticos betalactámicos: algoritmos de manejo y desensibilización como alternativa terapéutica vital.

Hypersensitivity reactions can be complex and life-threatening to patients, especially when drugs such as ß-lactam antibiotics are involved. To this day, there are diagnostic algorithms and mobile applications that improve the clinical approach, as well as laboratory tests and more specialized procedures, such as skin tests and controlled exposure tests; which are useful for identifying the drug involved and for selecting safe and effective therapeutic alternatives. For several years, the desensitization procedure has been positioned as a vital tool for clinical allergists and for their patients, and it is key to improving clinical outcomes such as survival and quality of life.

Las reacciones de hipersensibilidad pueden ser complejas y poner en peligro la vida de los pacientes, más cuando se involucran medicamentos como los antibióticos betalactámicos. A la fecha, se dispone de algoritmos diagnósticos y aplicaciones móviles que facilitan el abordaje clínico, así como pruebas de laboratorio y procedimientos más especializados, como las pruebas cutáneas y de exposición controlada, útiles para la identificación de la sustancia implicada y para la selección de alternativas terapéuticas seguras y efectivas. Desde hace varios años, el procedimiento de desensibilización se ha posicionado como una herramienta vital para el alergólogo clínico y los pacientes, y es clave para mejorar los desenlaces clínicos, tanto la supervivencia como la calidad de vida.

IgE, blood eosinophils and FeNO are not enough for choosing a monoclonal therapy among the approved options in patients with type 2 severe asthma.

Type-2 inflammation is the most frequent endophenotype of asthma. Different biomarkers have been proposed to identify this inflammation because highly effective therapies have improved type-2 severe asthma control. We investigated the frequency of some biomarkers of type-2 inflammation (total IgE, sIgE, blood eosinophil, and FeNO) in the framework of severe asthma and assessed its ability to help us to choose the best biological therapy for each patient. Different scenarios (sensitivity analysis) were evaluated according to the biomarkers proposed for each biological therapy in 72 patients with type-2 severe asthma. Between 54.1% and 68% of patients could receive at least 2 different biological therapies and 34.7%-40.2% could receive any of the 3 types of therapies (anti-IgE, anti-eosinophil, anti-IL4). Biomarkers help to identify type-2 severe asthma but total IgE, sIgE, blood eosinophil, and FeNO are not enough to select 1 specific therapy. With the increasing arrival of new biological therapies, it is necessary to identify new biomarkers that allow us to improve our selection criteria for the best therapy for each patient or to construct a prediction rule.

Linkage rules for plant-pollinator networks: trait complementarity or exploitation barriers?

Recent attempts to examine the biological processes responsible for the general characteristics of mutualistic networks focus on two types of explanations: nonmatching biological attributes of species that prevent the occurrence of certain interactions ("forbidden links"), arising from trait complementarity in mutualist networks (as compared to barriers to exploitation in antagonistic ones), and random interactions among individuals that are proportional to their abundances in the observed community ("neutrality hypothesis"). We explored the consequences that simple linkage rules based on the first two hypotheses (complementarity of traits versus barriers to exploitation) had on the topology of plant-pollination networks. Independent of the linkage rules used, the inclusion of a small set of traits (two to four) sufficed to account for the complex topological patterns observed in real-world networks. Optimal performance was achieved by a "mixed model" that combined rules that link plants and pollinators whose trait ranges overlap ("complementarity models") and rules that link pollinators to flowers whose traits are below a pollinator-specific barrier value ("barrier models"). Deterrence of floral parasites (barrier model) is therefore at least as important as increasing pollination efficiency (complementarity model) in the evolutionary shaping of plant-pollinator networks.

Internal dispersal of seeds by waterfowl: effect of seed size on gut passage time and germination patterns.

Long distance dispersal may have important consequences for gene flow and community structure. The dispersal of many plants depends on transport by vertebrate seed dispersers. The shapes of seed shadows produced by vertebrates depend both on movement patterns of the dispersers and on the dynamics and effects of passage through the disperser's gut (i.e. the retention time, survival and germination of ingested seeds). A combination of experiments with captive waterbirds and aquatic plant seeds was used to analyse the following: (a) the effects of inter- and intra-specific variation in seed size and duck species on seed retention time in the gut and (b) the relationship between retention time and the percent germination and germination rates of seeds. Among the three Scirpus species used, those with smaller seeds showed higher survival after ingestion by birds and longer retention times inside their guts than those with larger seeds. For Potamogeton pectinatus, only seeds from the smaller size class (<8 mg) survived ingestion. Retention time affected the percent germination and germination rate of Scirpus seeds but in a manner that varied for the different plant and bird species studied. We recorded both linear and non-linear effects of retention time on percent germination. In addition, germination rate was positively correlated with retention time in Scirpus litoralis but negatively correlated in Scirpus lacustris. Small seed size can favour dispersal over larger distances. However, the effects of retention time on percent germination can modify the seed shadows produced by birds due to higher percent germination of seeds retained for short or intermediate periods. The changes in dispersal quality associated with dispersal distance (which is expected to be positively related to retention time) will affect the probability of seedling establishment over longer distances and, thus, the spatial characteristics of the effective seed shadow.

The current state of the knowledge about local allergic rhinitis.

In recent years, a new phenotype of rhinitis has been described; it is characterized by the local production of specific IgE. There isn't any evidence of systemic atopy and it has been called local allergic rhinitis. Understanding the involved physiopathological mechanisms and the behavior of this phenotype translates into the development of strategies and treatments that improve the quality of life of patients with this disease. Below, we present an updated review of the available information regarding this disease and also of the aspects that are yet unresolved.

En los últimos años se ha descrito un nuevo fenotipo de rinitis, caracterizado por la producción local de IgE específica, sin evidencia de atopia sistémica, el cual se ha denominado rinitis alérgica local. Entender los mecanismos fisiopatológicos implicados y el comportamiento de este fenotipo se traducen en el desarrollo de estrategias y tratamientos que mejoran la calidad de vida de los pacientes con esta enfermedad. En este documento se presenta una revisión actualizada de la información disponible relativa a esta enfermedad y de los aspectos pendientes por resolver.

Continuous variation in herkogamy enhances the reproductive response of Lonicera implexa to spatial variation in pollinator assemblages.

Herkogamy, the spatial separation of sex organs in hermaphroditic plants, has been proposed as a mechanism to reduce self-pollination and the associated processes of inbreeding and gamete wastage. Longitudinal herkogamy is the most frequent type, with two subtypes: approach herkogamy (anthers below the stigma), which is associated with diverse pollinator arrays, and reverse herkogamy (anthers above the stigma), associated with specialized, long-tongued pollinators. By using a herkogamy index that varied continuously from negative (reverse herkogamy) to positive (approach herkogamy) values, we studied the effect of continuous variation in herkogamy on pollinator attraction, selfing capability and plant fitness across three populations of Lonicera implexa differing in the relative abundance of long-tongued vs. short-tongued pollinators. Reverse herkogamy was significantly more frequent in the population where long-tongued pollinators were dominant than in the other two populations. Agreeing with this, the main floral visitors of L. implexa individuals with small and large herkogamy index were, respectively, long-tongued and short-tongued pollinators. Spontaneous selfing was low and increased with increasing herkogamy index (i.e. with approach herkogamy), although most of it occurred when there was close distance between anthers and stigma. Fruit production was unrelated to the herkogamy index in the population with long-tongued pollinators, but it increased with approach herkogamy (higher herkogamy index) in the other two populations. In contrast, seeds of individuals with reverse herkogamy (smaller herkogamy indices) germinated better. In this species, continuous variation in herkogamy might function as a reproductive strategy, as different morphotypes might be favoured by different pollinator assemblages.