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Relationships between genetic (allozyme) variation and landscape age and structure were investigated in 17 calcareous grassland demes of the moss Homalothecium lutescens (Hedw.) H. Rob. on the Baltic island of Oland. Mean within-deme gene diversity ([H.sub.S] = 0.152) was moderate compared with other bryophyte studies, and the between-deme proportion of the total diversity ([G.sub.ST] = 0.100, Jost's D = 0.011) was low but significantly different from zero. Clonal mixing, measured as the proportion of two adjacent shoots having different haplotypes, was relatively high (mean 0.32 over all demes). [H.sub.S] was higher in old grassland fragments, but negatively related to vascular plant species richness. Allelic richness (A) was positively associated with the area of old (≥ 280 years) grassland in the surroundings: although demes in old grasslands are genetically more variable than those in younger grasslands, proximity to large areas of old grassland may promote genetic variability even in younger grassland demes. The importance of management continuity for species diversity has been stressed in many earlier grassland studies. Here, we conclude that grassland fragments with a long history of grazing continuity are also positively associated with variability at within-species level, as exemplified by the bryophyte H. lutescens. Key words: allozymes, bryophytes, calcareous grassland, genetic variation, landscape history. Dans dix-sept prairies calcaires de Ule d'Oland sur la Baltique, l'auteure a etudie les relations entre la variation genetique (allozyme) et l'age, avec la structure des demes de la mousse Homalothecium lutescens (Hedw.) H. Rob. La variation genetique moyenne pour un deme donne ([H.sub.S] = 0,152) est moderee comparativement a d'autres etudes de bryophytes et la proportion de la variation totale entre demes ([G.sub.ST] = 0,100, Jost's D = 0,011) est faible, mais significativement differente de zero. Le melange clonal mesure comme la proportion de deux tiges adjacentes ayant des haplotypes differents, est relativement elevee (moyenne de 0,32 pour l'ensemble des demes). La diversite genetique pour [H.sub.S] s'avere plus elevee dans les fragments de vieilles prairies, mais negativement reliee a la richesse en especes de plantes vasculaires. La richesse allelique (A) montre une association positive reliee avec l'aire de la vieille prairie ([greater than or equal to] 280 ans) environnante: bien que les demes de la vieille prairie soient genetiquement plus variables que celles des prairies plus jeunes, la proximite de grandes surfaces de vieilles prairies peut promouvoir la variabilite genetique, meme dans les demes des prairies plus jeunes. On a deja souligne l'importance de la continuite de l'amenagement pour la diversite des especes dans des etudes antecedentes sur les prairies. L'auteure conclut que les fragments de prairies ayant connu une longue continuite de paturage sont egalement associes avec de la variabilite a l'echelle intra specifique, comme le montre la bryophyte H. lutescens. [Traduit par la Redaction] Mots-cles: allozymes, bryophytes, prairie calcaire, variation genetique, histoire du paysage., Introduction The potential for species or populations to adapt to a changing environment is expected to be influenced by the levels of genetic variation that are available for natural selection [...]

The dioecious weed Silene latifolia Poiret is thought to have spread northwards through Europe from separate southern source populations and shows a pronounced east-west pattern of differentiation in seed morphology. We used crossing experiments to investigate whether patterns of interfertility in S. latifolia are consistent with a scenario of ongoing speciation (reflected by outbreeding depression in crosses between the seed races), a scenario involving local inbreeding (reflected by heterosis in interpopulations crosses), or a combination of both scenarios. The experiments involved three western and three eastern populations, which were crossed reciprocally in all possible inter- and intra-population combinations. Inter-race cross-progenies did not have lower fitness than those from intraracial crosses, and the results are not consistent with a scenario of incipient speciation. A pattern of overall heterosis was found in three variables, indicating the expression of inbreeding depression in progeny from intrapopulation crosses. For two fitness variables, negative relationships between interpopulation distance and heterosis, together with signs of outbreeding depression in the longest-distance crosses, suggest that there may be significant levels of genetic differentiation between geographically distant populations. The sex ratio was female-biased in most progenies, especially in those from the longest-distance crosses. Key words: experimental hybridization, heterosis, inbreeding depression, incipient speciation, outbreeding depression, sex ratio. On croft que la plante adventice dioique Silene latifolia Poiret s'est etendue vers le nord de l'Europe a partir de populations sources meridionales distactes et on observe un patron marque est-ouest dans la differenciation de sa morphologie seminale. Les auteurs ont conduit des experiences de croisement pour determiner si les patrons d'interfertilite du S. latifolia concordent avec un scenario de speciation continue (traduit par une depression dans les croisements entre les races de graines), un scenario impliquant un autocroisement local (indique par l'heterosis dans les croisements entre populations) ou une combinaison des deux scenarios. Les experiences impliquent trois populations occidentales et trois populations orientales qu'on a croisees reciproquement selon toutes les combinaisons entre et dans les populations. Les progenitures provenant de croisements entre races ne montrent pas moms d' adaptation que les croisements dans la race, et les resultats ne concordent pas avec un scenario de speciation naissante. On observe un patron d'heterosis general pour trois variables, ce qui indique l'expression dune depression d'autocroisement dans la progeniture provenant de croisements dans la population. Pour deux des trois variables d' adaptation, on observe des relations negatives selon les distances entre populations et l'heterosis, lesquelles, prises ensemble avec les signes de depression par croisements externes sur de longues distances, suggerent qu'il puisse y avoir des degres significatifs de differenciation genetique entre les populations geographiquement eloignees. Les rapports sexuels montrent un bicis en faveur des femelles chez la plupart des progenitures, surtout chez cenes provenant de croisements sur les distances les plus longues. Mots-cles : hybridation experimentale, heterosis, depression d'autocroisement, speciation naissante, depression decoulant du croisement, proportions des sexes. [Traduit par la Redaction], Introduction Conspecific populations that are separated from each other, for example by geographic distance or physical barriers, may diverge genetically and phenotypically as a result of local selection and (or) [...]

Recent divergence can obscure species boundaries among closely related taxa. Silene section Italicae (Caryophyllaceae) has been taxonomically controversial, with about 30 species described. We investigate species delimitation within this section using 500 specimens sequenced for one nuclear and two plastid markers. Despite the use of a small number of genes, the large number of sequenced samples allowed confident delimitation of 50% of the species. The delimitation of other species (e.g., Silene nemoralis, S. nodulosa and S. andryalifolia) was more challenging. We confirmed that seven of the ten chasmophyte species in the section are not related to each other but are, instead, genetically closer to geographically nearby species belonging to Italicae yet growing in open habitats. Adaptation to chasmophytic habitats therefore appears to have occurred independently, as a result of convergent evolution within the group. Species from the Western Mediterranean Basin showed more conflicting species boundaries than species from the Eastern Mediterranean Basin, where there are fewer but better-delimited species. Significant positive correlations were found between an estimation of the effective population size of the taxa and their extent of occurrence (EOO) or area of occupancy (AOO), and negative but non-significant correlations between the former and the posterior probability (PP) of the corresponding clades. These correlations might suggest a lower impact of incomplete lineage sorting in species with low effective population sizes and small distributional ranges compared with that in species inhabiting large areas. Finally, we confirmed that S. italica and S. nemoralis are distinct species, that S. nemoralis might furthermore include two different species and that S. velutina from Corsica and S. hicesiae from the Lipari Islands are sister species. [ABSTRACT FROM AUTHOR]

1. There is an increasing recognition that, although the climate change and biodiversity crises are fundamentally connected, they have been primarily addressed independently and a more integrated global approach is essential to tackle these two global challenges. 2. Nature-based Solutions (NbS) are hailed as a pathway for promoting synergies between the climate change and biodiversity agendas. There are, however, uncertainties and difficulties associated with the implementation of NbS, while the evidence regarding their benefits for biodiversity remains limited. 3. We identify five key research areas where incomplete or poor information hinders the development of integrated biodiversity and climate solutions. These relate to refining our understanding of how climate change mitigation and adaptation approaches benefit biodiversity conservation; enhancing our ability to track and predict ecosystems on the move and/or facing collapse; improving our capacity to predict the impacts of climate change on the effectiveness of NbS; developing solutions that match the temporal, spatial and functional scale of the challenges; and developing a comprehensive and practical framework for assessing, and mitigating against, the risks posed by the implementation of NbS. 4. Policy implications. The Conference of the Parties (COP) for the United Nations Framework Convention on Climate Change (COP26) and the Convention on Biological Diversity (COP15) present a clear policy window for developing coherent policy frameworks that align targets across the nexus of biodiversity and climate change. This window should (a) address the substantial and chronic underfunding of global biodiversity conservation, (b) remove financial incentives that negatively impact biodiversity and/or climate change, (c) develop higher levels of integration between the biodiversity and climate change agendas, (d) agree on a monitoring framework that enables the standardised quantification and comparison of biodiversity gains associated with NbS across ecosystems and over time and (e) rethink environmental legislation to better support biodiversity conservation in times of rapid climatic change. [ABSTRACT FROM AUTHOR]

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Copyright of Methods in Ecology & Evolution is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Phosphoglucose isomerase (PGI, EC 5.3.1.9) is an essential metabolic enzyme in all eukaryotes. An earlier study of the PgiC1 gene, which encodes cytosolic PGI in the grass Festuca ovina L., revealed a marked difference in the levels of nucleotide polymorphism between the 5' and 3' portions of the gene. Methods: In the present study, we characterized the sequence polymorphism in F. ovina PgiC1 in more detail and examined possible explanations for the non-uniform pattern of nucleotide polymorphism across the gene. Results: Our study confirms that the two portions of the PgiC1 gene show substantially different levels of DNA polymorphism and also suggests that the peptide encoded by the 3' portion of PgiC1 is functionally and structurally more important than that encoded by the 5' portion. Although there was some evidence of purifying selection (dN/dS test) on the 5' portion of the gene, the signature of purifying selection was considerably stronger on the 3' portion of the gene (dN/dS and McDonald-Kreitman tests). Several tests support the action of balancing selection within the 5' portion of the gene. Wall's B and Q tests were significant only for the 5' portion of the gene. There were also marked peaks of nucleotide diversity, Tajima's D and the dN/dS ratio at or around a PgiC1 codon site (within the 5' portion of the gene) that a previous study had suggested was subject to positive diversifying selection. Conclusions: Our results suggest that the two portions of the gene have been subject to different selective regimes. Purifying selection appears to have been the main force contributing to the relatively low level of polymorphism within the 3' portion of the sequence. In contrast, it is possible that balancing selection has contributed to the maintenance of the polymorphism within the 5' portion of the gene. [ABSTRACT FROM AUTHOR]

Semi-natural grasslands with grazing management are characterized by high fine-scale species richness and have a high conservation value. The fact that fine-scale surveys of grassland plant communities are time-consuming may limit the spatial extent of ground-based diversity surveys. Remote sensing tools have the potential to support field-based sampling and, if remote sensing data are able to identify grassland sites that are likely to support relatively higher or lower levels of species diversity, then field sampling efforts could be directed towards sites that are of potential conservation interest. In the present study, we examined whether aerial hyperspectral (414-2501 nm) remote sensing can be used to predict fine-scale plant species diversity (characterized as species richness and Simpson's diversity) in dry grazed grasslands. Vascular plant species were recorded within 104 (4 m × 4 m) plots on the island of Öland (Sweden) and each plot was characterized by a 245-waveband hyperspectral data set. We used two different modeling approaches to evaluate the ability of the airborne spectral measurements to predict within-plot species diversity: (1) a spectral response approach, based on reflectance information from (i) all wavebands, and (ii) a subset of wavebands, analyzed with a partial least squares regression model, and (2) a spectral heterogeneity approach, based on the mean distance to the spectral centroid in an ordinary least squares regression model. Species diversity was successfully predicted by the spectral response approach (with an error of ca. 20%) but not by the spectral heterogeneity approach. When using the spectral response approach, iterative selection of important wavebands for the prediction of the diversity measures simplified the model but did not improve its predictive quality (prediction error). Wavebands sensitive to plant pigment content (400-700 nm) and to vegetation structural properties, such as above-ground biomass (700-1300 nm), were identified as being the most important predictors of plant species diversity. We conclude that hyperspectral remote sensing technology is able to identify fine-scale variation in grassland diversity and has a potential use as a tool in surveys of grassland plant diversity. [ABSTRACT FROM AUTHOR]

The dimeric metabolic enzyme phosphoglucose isomerase (PGI, EC 5.3.1.9) plays an essential role in energy production. In the grass Festuca ovina, field surveys of enzyme variation suggest that genetic variation at cytosolic PGI (PGIC) may be adaptively important. In the present study, we investigated the molecular basis of the potential adaptive significance of PGIC in F. ovina by analyzing cDNA sequence variation within the PgiC1 gene. Two, complementary, types of selection test both identified PGIC1 codon (amino acid) sites 200 and 173 as candidate targets of positive selection. Both candidate sites involve charge-changing amino acid polymorphisms. On the homology-modeled F. ovina PGIC1 3-D protein structure, the two candidate sites are located on the edge of either the inter-monomer boundary or the inter-domain cleft; examination of the homology-modeled PGIC1 structure suggests that the amino acid changes at the two candidate sites are likely to influence the inter-monomer interaction or the domain-domain packing. Biochemical studies in humans have shown that mutations at several amino acid sites that are located close to the candidate sites in F. ovina, at the inter-monomer boundary or the inter-domain cleft, can significantly change the stability and/or kinetic properties of the PGI enzyme. Molecular evolutionary studies in a wide range of other organisms suggest that PGI amino acid sites with similar locations to those of the candidate sites in F. ovina may be the targets of positive/balancing selection. Candidate sites 200 and 173 are the only sites that appear to discriminate between the two most common PGIC enzyme electromorphs in F. ovina: earlier studies suggest that these electromorphs are implicated in local adaptation to different grassland microhabitats. Our results suggest that PGIC1 sites 200 and 173 are under positive selection in F. ovina. [ABSTRACT FROM AUTHOR]

Uncultivated field margins are one of the most frequent non-crop habitat types in contemporary, high-intensity agricultural landscapes and may therefore be important for the persistence of many farmland species. Managing field margins in a way that preserves, and preferably enhances, their value for biodiversity is therefore important. In the present study, we evaluate how the flora of uncultivated field margins is affected by the removal of woody vegetation as prescribed by an agri-environment scheme (AES) under the Swedish Rural Development Program 2007–2013. We used generalized linear mixed models and detrended correspondence analysis to compare the flora of open (cleared) and more overgrown field margins, located within agricultural landscapes of different complexity, in Scania, S. Sweden. As expected, there was a negative effect of management on woody species. However, the local (1 m 2 ) and transect (100 m) level richness of non-woody species did not differ significantly between management categories, and there were no differences in the within-transect variability of non-woody species (local β diversity) or the species composition (0.25 m 2 plots) in managed and unmanaged field margins. Our results show that the removal of woody vegetation from uncultivated field margins, as prescribed by the evaluated AES, is unlikely to benefit non-woody plant species. The species composition of the sampled field margins suggests that inclusion of appropriate field layer management alone is unlikely to be sufficient to improve habitat conditions for grassland species unless measures are taken to counteract eutrophication. Landscape type, on the other hand, influenced both the total richness and the richness of each of the species groups that were considered to be of particular conservation value in the present study: field margins in the complex agricultural landscapes were significantly richer than those in the simple ones. Maintaining non-crop habitat at the landscape scale is likely to be a necessary first step in the prevention of a further decline of farmland plants. [ABSTRACT FROM AUTHOR]