Marcescent corollas as functional structures: effects on the fecundity of two insect-pollinated plants

† Background and aims Persistence of withered corollas after anthesis (‘corolla marcescence’) is widespread in angiosperms, yet its functional significance does not seem to have been explored for any species. This note reports the results of experiments assessing the fecundity effects of marcescent corollas in two southern Spanish insect-pollinated plants, Lavandula latifolia (Lamiaceae) and Viola cazorlensis (Violaceae). † Methods The effect of marcescent corollas on seed production was evaluated experimentally on wild-growing plants. Newly open flowers were randomly assigned to either control or treatment groups in experimental plants. After anthesis, withered corollas of treatment flowers were removed and those in control flowers were left in place. Fruits produced by treatment and control flowers were collected shortly before dehiscence and the number of seeds counted. † Key Results In V. cazorlensis, removal of withered corollas had no effect on percentage of fruit set, but mean seeds per fruit increased from 9.5 to 11.4. In L. latifolia, corolla removal had no effect on the number of seeds per fruit, but reduced the proportion of flowers ripening fruit from 60 % to 40 %. The detrimental effect of corolla removal on L. latifolia fecundity resulted from the drastic increase in fruit infestation by seed-predatory cecido- myiid larvae, which occurred in 4 % and 34 % of control and treatment fruits, respectively. † Conclusions Because of their potential effects on plant fecundity, marcescent corollas should not be dismissed a priori as biologically irrelevant leftovers from past floral functions. The simplicity of the experimental layout required to test for short-term fecundity effects of corolla marcescence should help to achieve a better understand- ing of the ecological and evolutionary correlates of this widespread but poorly understood trait.Peer reviewe

Flower traits, habitat, and phylogeny as predictors of pollinator service: a plant community perspective

Pollinator service is essential for successful sexual reproduction and long-term population persistence of animal-pollinated plants, and innumerable studies have shown that insufficient service by pollinators results in impaired sexual reproduction (“pollen limitation”). Studies directly addressing the predictors of variation in pollinator service across species or habitats remain comparatively scarce, which limits our understanding of the primary causes of natural variation in pollen limitation. This paper evaluates the importance of pollination-related features, evolutionary history, and environment as predictors of pollinator service in a large sample of plant species from undisturbed montane habitats in southeastern Spain. Quantitative data on pollinator visitation were obtained for 191 insect-pollinated species belonging to 142 genera in 43 families, and the predictive values of simple floral traits (perianth type, class of pollinator visitation unit, and visitation unit dry mass), phylogeny, and habitat type were assessed. A total of 24,866 pollinator censuses accounting for 5,414,856 flower-minutes of observation were conducted on 510 different dates. Flowering patch and single flower visitation probabilities by all pollinators combined were significantly predicted by the combined effects of perianth type (open vs. restricted), class of visitation unit (single flower vs. flower packet), mass of visitation unit, phylogenetic relationships, and habitat type. Pollinator composition at insect order level varied extensively among plant species, largely reflecting the contrasting visitation responses of Coleoptera, Diptera, Hymenoptera, and Lepidoptera to variation in floral traits. Pollinator composition had a strong phylogenetic component, and the distribution of phylogenetic autocorrelation hotspots of visitation rates across the plant phylogeny differed widely among insect orders. Habitat type was a key predictor of pollinator composition, as major insect orders exhibited decoupled variation across habitat types in visitation rates. Comprehensive pollinator sampling of a regional plant community has shown that pollinator visitation and composition can be parsimoniously predicted by a combination of simple floral features, habitat type, and evolutionary history. Ambitious community-level studies can help to formulate novel hypotheses and questions, shed fresh light on long-standing controversies in pollination research (e.g., “pollination syndromes”), and identify methodological cautions that should be considered in pollination community studies dealing with small, phylogenetically biased plant species samples

Genetic and epigenetic divergence between disturbed and undisturbed subpopulations of a Mediterranean shrub:a 20-year field experiment

Little is known on the potential of ecological disturbance to cause genetic andepigenetic changes in plant populations. We take advantage of a long-term fieldexperiment initiated in 1986 to study the demography of the shrub Lavandulalatifolia, and compare genetic and epigenetic characteristics of plants in twoadjacent subplots, one experimentally disturbed and one left undisturbed,20 years after disturbance. Experimental setup was comparable to an unrepli-cated ‘Before-After-Control-Impact’ (BACI) design where a single pair of per-turbed and control areas were compared. When sampled in 2005, plants in thetwo subplots had roughly similar ages, but they had established in contrastingenvironments: dense conspecific population (‘Undisturbed’ subpopulation) ver-sus open area with all conspecifics removed (‘Disturbed’ subpopulation). Plantswere characterized genetically and epigenetically using amplified fragmentlength polymorphism (AFLP) and two classes of methylation-sensitive AFLP(MSAP) markers. Subpopulations were similar in genetic diversity but differedin epigenetic diversity and multilocus genetic and epigenetic characteristics.Epigenetic divergence between subpopulations was statistically unrelated togenetic divergence. Bayesian clustering revealed an abrupt linear boundarybetween subpopulations closely coincident with the arbitrary demarcation linebetween subplots drawn 20 years back, which supports that genetic and epige-netic divergence between subpopulations was caused by artificial disturbance.There was significant fine-scale spatial structuring of MSAP markers in bothsubpopulations, which in the Undisturbed one was indistinguishable from thatof AFLP markers. Genetic differences between subpopulations could beexplained by divergent selection alone, while the concerted action of divergentselection and disturbance-driven appearance of new methylation variants in theDisturbed subpopulation is proposed to explain epigenetic differences. Thisstudy provides the first empirical evidence to date suggesting that relativelymild disturbances could leave genetic and epigenetic signatures on the nextadult generation of long-lived plants.Peer reviewe

Coupling Human Mobility and Social Ties

Studies using massive, passively data collected from communication technologies have revealed many ubiquitous aspects of social networks, helping us understand and model social media, information diffusion, and organizational dynamics. More recently, these data have come tagged with geographic information, enabling studies of human mobility patterns and the science of cities. We combine these two pursuits and uncover reproducible mobility patterns amongst social contacts. First, we introduce measures of mobility similarity and predictability and measure them for populations of users in three large urban areas. We find individuals' visitations patterns are far more similar to and predictable by social contacts than strangers and that these measures are positively correlated with tie strength. Unsupervised clustering of hourly variations in mobility similarity identifies three categories of social ties and suggests geography is an important feature to contextualize social relationships. We find that the composition of a user's ego network in terms of the type of contacts they keep is correlated with mobility behavior. Finally, we extend a popular mobility model to include movement choices based on social contacts and compare it's ability to reproduce empirical measurements with two additional models of mobility

On the potential biases of scientific estimates of catches of tropical tunas of purse seiners the EU and other countries report to the ICCAT and IOTC

This document represents a first attempt to explore potential differences between the catches of tropical tunas estimated using the EU software T3 and those recorded on sale slips completed by the canning factories purchasing fish from vessels registered with OPAGAC in the Atlantic and Indian oceans, over the period 2011-16. The analysis identified potential sources of bias estimates of catch of tropical tunas may be subject to, of different magnitude depending on the ocean, fleet, and size category. The largest bias was recorded in the Indian Ocean. In the Atlantic Ocean the catches of yellowfin and bigeye tunas seem to be also underestimated, with underestimation of both large and small fish. Although the study is preliminary, the results obtained indicate that the system the EU is using to sample purse seine landings and estimate catches may be subject to bias which, if confirmed, could have consequences on the statistics, stock assessments, management advice, and management measures adopted by ICCAT and IOT

Invisible floral larcenies: microbial communities degrade floral nectar of bumble bee-pollinated plants

8 páginas, 4 figuras, 1 láminaThe ecology of nectarivorous microbial communities remains virtually unknown, which precludes elucidating whether these organisms play some role in plant–pollinator mutualisms beyond minor commensalism. We simultaneously assessed microbial abundance and nectar composition at the individual nectary level in flowers of three southern Spanish bumble bee-pollinated plants (Helleborus foetidus, Aquilegia vulgaris, and Aquilegia pyrenaica cazorlensis). Yeasts were frequent and abundant in nectar of all species, and variation in yeast density was correlated with drastic changes in nectar sugar concentration and composition. Yeast communities built up in nectar from early to late floral stages, at which time all nectaries contained yeasts, often at densities between 104 and 105 cells/mm3. Total sugar concentration and percentage sucrose declined, and percentage fructose increased, with increasing density of yeast cells in nectar. Among-nectary variation in microbial density accounted for 65% (H. foetidus and A. vulgaris) and 35% (A. p. cazorlensis) of intraspecific variance in nectar sugar composition, and 60% (H. foetidus) and 38% (A. vulgaris) of variance in nectar concentration. Our results provide compelling evidence that nectar microbial communities can have detrimental effects on plants and/or pollinators via extensive nectar degradation and also call for a more careful interpretation of nectar traits in the future, if uncontrolled for yeasts.Work was supported by grants 2005-RNM-156 (Consejería de Innovación, Ciencia y Empresa, Junta de Andalucía) and by CGL2006-01355 and EXPLORA CGL2007-28866-E/BOS (Ministerio de Educación y Ciencia, Gobierno de España).Peer reviewe

Epigenetic variation predicts regional and local intraspecific functional diversity in a perennial herb

The ecological significance of epigenetic variation has been generally inferred from studies on model plants under artificial conditions, but the importance of epigenetic differences between individuals as a source of intraspecific diversity in natural plant populations remains essentially unknown. This study investigates the relationship between epigenetic variation and functional plant diversity by conducting epigenetic (methylation-sensitive amplified fragment length polymorphisms, MSAP) and genetic (amplified fragment length polymorphisms, AFLP) marker-trait association analyses for 20 whole-plant, leaf and regenerative functional traits in a large sample of wild-growing plants of the perennial herb Helleborus foetidus from ten sampling sites in south-eastern Spain. Plants differed widely in functional characteristics, and exhibited greater epigenetic than genetic diversity, as shown by per cent polymorphism of MSAP fragments (92%) or markers (69%) greatly exceeding that for AFLP ones (41%). After controlling for genetic structuring and possible cryptic relatedness, every functional trait considered exhibited a significant association with at least one AFLP or MSAP marker. A total of 27 MSAP (13.0% of total) and 12 AFLP (4.4%) markers were involved in significant associations, which explained on average 8.2% and 8.0% of trait variance, respectively. Individual MSAP markers were more likely to be associated with functional traits than AFLP markers. Between-site differences in multivariate functional diversity were directly related to variation in multilocus epigenetic diversity after multilocus genetic diversity was statistically accounted for. Results suggest that epigenetic variation can be an important source of intraspecific functional diversity in H. foetidus, possibly endowing this species with the capacity to exploit a broad range of ecological conditions despite its modest genetic diversity.Peer Reviewe

To be or not to be better pollinated: Differences between sex morphs in marginal gynodioecious populations

PREMISE OF THE STUDY: Changes in the pollinator communities of marginal plant populations can affect their pollination quantity or quality. Geographic variation in pollination success can alter the reproductive advantage that female plants require to persist within gynodioecious populations. Particularly valuable is determining the pollination success at the prezygotic stage in self-compatible gynodioecious species whose females do not exhibit enhanced seed production. METHODS: In core and marginal populations of Daphne laureola, we analyzed the differences between hermaphrodites and females in the proportion of flowers visited, the stigma pollen loads, and the quantity of pollen tubes in styles. We also examined the relationship between the number of pollen tubes in styles vs. the number of pollen grains on stigmas using piecewise regression and binomial generalized linear mixed models. KEY RESULTS: Pollinators deposited larger pollen loads on flowers in marginal populations. In marginal populations, female flowers received more pollinator visits and more pollen grains on their stigmas, and they had more pollen tubes in their styles than did female flowers in core populations. Both piecewise regression and binomial GLMM analyses showed that females in marginal populations had a lower proportion of grains that developed tubes than females in the core populations, which suggests decreased pollination quality. CONCLUSIONS: More efficient pollination services in marginal populations decreased the overall differences in the prezygotic pollination success between the sex morphs. Our results also suggest that pollination quality is lower in females of marginal populations, which could be counteracting the increased pollination in females in marginal populations.Peer Reviewe

MSAP markers and global cytosine methylation in plants: a literature survey and comparative analysis for a wild-growing species

Methylation of DNA cytosines affects whether transposons are silenced and genes are expressed, and is a major epigenetic mechanism whereby plants respond to environmental change. Analyses of methylation-sensitive amplification polymorphism (MS-AFLP or MSAP) have been often used to assess methyl-cytosine changes in response to stress treatments and, more recently, in ecological studies of wild plant populations. MSAP technique does not require a sequenced reference genome and provides many anonymous loci randomly distributed over the genome for which the methylation status can be ascertained. Scoring of MSAP data, however, is not straightforward, and efforts are still required to standardize this step to make use of the potential to distinguish between methylation at different nucleotide contexts. Furthermore, it is not known how accurately MSAP infers genome-wide cytosine methylation levels in plants. Here, we analyse the relationship between MSAP results and the percentage of global cytosine methylation in genomic DNA obtained by HPLC analysis. A screening of literature revealed that methylation of cytosines at cleavage sites assayed by MSAP was greater than genome-wide estimates obtained by HPLC, and percentages of methylation at different nucleotide contexts varied within and across species. Concurrent HPLC and MSAP analyses of DNA from 200 individuals of the perennial herb Helleborus foetidus confirmed that methyl-cytosine was more frequent in CCGG contexts than in the genome as a whole. In this species, global methylation was unrelated to methylation at the inner CG site. We suggest that global HPLC and context-specific MSAP methylation estimates provide complementary information whose combination can improve our current understanding of methylation-based epigenetic processes in nonmodel plants.Peer reviewe

Assessing users expectations and perceptions on different beach types and the need for diverse management frameworks along the Western Mediterranean

[EN] Beach management follows a homogeneous and rigid decision-making process that tries to fulfill expectations assumed from mass tourism without really getting to know the real users' perception. Decisions are usually taken without considering the diversity of values of the beaches, causing high environmental, economic and recreational impacts. In this study, users' profiles, expectations and perceptions have been defined on six Valencian beaches with both different degree of artificialization and sediment type. This has allowed a comparison between semi-natural and urban beaches, and between pebbly and sandy beaches. Differences between beach types have been observed, and a critical analysis of the current management framework and practices has been carried out. Therefore, decision-making should take greater account of users, and actions should be adapted to the diversity of beaches and their particularities, leading to a differential beach management.This study integrates findings and results obtained within the framework of the FPU15/04501 granted by the Ministry of Education, Culture and Sports to C. Cabezas-Rabadan, and by the funds of the research project RESETOCOAST (CGL2015-69906-R) supported by the Ministry of Economy, Industry and Competitiveness.Cabezas-Rabadán, C.; Rodilla, M.; Pardo Pascual, JE.; Herrera-Racionero, P. (2019). Assessing users expectations and perceptions on different beach types and the need for diverse management frameworks along the Western Mediterranean. Land Use Policy. 81:219-231. https://doi.org/10.1016/j.landusepol.2018.10.027S2192318