The role of seed traits in determining the phylogenetic structure of temperate plant communities

8 páginas, 2 figuras, 3 tablas.Phylogenetic clustering of species within plant communities can be expected to result from environmental filtering acting on an evolutionary-conserved plant trait. One such a candidate trait is the embryo to seed-size ratio (E:S). A high E:S may allow faster germination immediately after imbibition, and is therefore assumed to be advantageous in dry habitats. In this study the hypothesis was tested that habitat filtering driven by soil moisture conditions and acting on seed germination and seedling establishment is an important ecological mechanism in structuring temperate plant communities. Vegetation samplings were performed in three habitats located within 200 km of each other in western Europe: Ellenberg indicator values showed that the habitats selected differed substantially in terms of soil moisture and light availability. E.S ratio and seed mass data for all genera were obtained from literature. Data were analysed using recently developed phylogenetic methods. Genera with a similar E:S tend to co-occur, as low and high E:S genera dominate in moist and dry habitats, respectively. A phylogenetically clustered pattern of community structure was evident, and dispersion of E:S was positively related to phylogenetic dispersion. The phenotypically and phylogenetically clustered pattern indicates that E:S-mediated habitat filtering is an important assembly process structuring the plant community of the temperate climate habitats studied.We thank Tara Forbis for providing the data on the E:S and Olivier Hardy for providing access to the Spacodi software. We are grateful to Juli Pausas for helping with the statistical analyses. H. Jacquemyn, and J. Pausas improved the manuscript by providing useful comments. This work was funded by the Research Foundation-Flanders (FWO) and was conducted at the Centro de Investigaciones sobre Desertificación(CIDE) in Valencia.Peer reviewe

Population genomic structure of the gelatinous zooplankton species Mnemiopsis leidyi in its nonindigenous range in the North Sea

Nonindigenous species pose a major threat for coastal and estuarine ecosystems. Risk management requires genetic information to establish appropriate management units and infer introduction and dispersal routes. We investigated one of the most successful marine invaders, the ctenophore Mnemiopsis leidyi, and used genotyping-by-sequencing (GBS) to explore the spatial population structure in its nonindigenous range in the North Sea. We analyzed 140 specimens collected in different environments, including coastal and estuarine areas, and ports along the coast. Single nucleotide polymorphisms (SNPs) were called in approximately 40 k GBS loci. Population structure based on the neutral SNP panel was significant (F-ST .02; p < .01), and a distinct genetic cluster was identified in a port along the Belgian coast (Ostend port; pairwise F-ST .02-.04; p < .01). Remarkably, no population structure was detected between geographically distant regions in the North Sea (the Southern part of the North Sea vs. the Kattegat/Skagerrak region), which indicates substantial gene flow at this geographical scale and recent population expansion of nonindigenous M. leidyi. Additionally, seven specimens collected at one location in the indigenous range (Chesapeake Bay, USA) were highly differentiated from the North Sea populations (pairwise F-ST .36-.39; p < .01). This study demonstrates the utility of GBS to investigate fine-scale population structure of gelatinous zooplankton species and shows high population connectivity among nonindigenous populations of this recently introduced species in the North Sea. OPEN RESEARCH BADGES This article has earned an Open Data Badge for making publicly available the digitally-shareable data necessary to reproduce the reported results. The data is available at: The DNA sequences generated for this study are deposited in the NCBI sequence read archive under SRA accession numbers -, and will be made publically available upon publication of this manuscript

Habitat fragmentation reshapes genomic footprints of selection in a forest herb

Understanding the combined effects of climate change and habitat fragmentation on the adaptive potential of plant populations is essential for devising effective conservation strategies. This is particularly important where mating system variation impacts the evolutionary consequences of habitat fragmentation. Here we aimed to reveal how habitat fragmentation and climate adaptation jointly influence the evolutionary trajectories in Primula elatior, a heterostylous self-incompatible and dispersal-constrained forest herb. We quantified the genomic variation and degree of herkogamy, a floral trait reducing self-pollination, across 60 geographically paired populations of Primula elatior across Europe, each pair featuring contrasting levels of habitat fragmentation. Our findings revealed a large and unique set of adaptive outliers in more fragmented landscapes, compared to high-connectivity ones, despite the geographic proximity of the sampling pairs. This suggests elevated selective pressures in fragmented habitats, mirrored by a reduced adaptive potential to cope with climate change. Finally, a minority of genetic variants associated with herkogamy were influenced by current levels of habitat fragmentation and population size, potentially signalling early indicators of evolutionary mating system changes in response to pollinator limitation. Because evolutionary trajectories and adaptive potential are expected to be increasingly affected by habitat fragmentation, our findings underscore the importance of considering both habitat fragmentation and climate adaptation in conservation research and planning.Comment: 26 pages, 5 figure

Transposable elements maintain genome-wide heterozygosity in inbred populations.

Elevated levels of inbreeding increase the risk of inbreeding depression and extinction, yet many inbred species are widespread, suggesting that inbreeding has little impact on evolutionary potential. Here, we explore the potential for transposable elements (TEs) to maintain genetic variation in functional genomic regions under extreme inbreeding. Capitalizing on the mixed mating system of Arabidopsis lyrata, we assess genome-wide heterozygosity and signatures of selection at single nucleotide polymorphisms near transposable elements across an inbreeding gradient. Under intense inbreeding, we find systematically elevated heterozygosity downstream of several TE superfamilies, associated with signatures of balancing selection. In addition, we demonstrate increased heterozygosity in stress-responsive genes that consistently occur downstream of TEs. We finally reveal that TE superfamilies are associated with specific signatures of selection that are reproducible across independent evolutionary lineages of A. lyrata. Together, our study provides an important hypothesis for the success of self-fertilizing species

Genetic diversity and core subset selection in ex situ seed collections of the banana crop wild relative Musa balbisiana

Crop wild relatives (CWRs) play a key role in crop breeding by providing beneficial trait characteristics for improvement of related crops. CWRs are more efficiently used in breeding if the plant material is genetically characterized, but the diversity in CWR genetic resources has often poorly been assessed. Seven seed collections of Musa balbisiana, an important CWR of dessert and cooking bananas, originating from three natural populations, two feral populations and two ex situ field collections were retrieved and their genetic diversity was quantified using 18 microsatellite markers to select core subsets that conserve the maximum genetic diversity. The highest genetic diversity was observed in the seed collections from natural populations of Yunnan, a region that is part of M. balbisiana's centre of origin. The seeds from the ex situ field collections were less genetically diverse, but contained unique variation with regards to the diversity in all seed collections. Seeds from feral populations displayed low genetic diversity. Core subsets that maximized genetic distance incorporated almost no seeds from the ex situ field collections. In contrast, core subsets that maximized allelic richness contained seeds from the ex situ field collections. We recommend the conservation and additional collection of seeds from natural populations, preferentially originating from the species' region of origin, and from multiple individuals in one population. We also suggest that the number of seeds used for ex situ seed bank regeneration must be much higher for the seed collections from natural populations

PRELIMINARY BASELINE SURVEY OF AVIFAUNAL DIVERSITY IN JIMMA ZONE, SOUTH-WESTERN ETHIOPIA

Multidimensional poverty, which is deeply-rooted within least-developed African countries like Ethiopia, is forcing local people to heavily rely on natural resources for their subsistent livelihoods. As a result, remaining wilderness areas in tropical Africa which support huge but little known biological diversity, are subject to extensive habitat loss, fragmentation and degradation in turn causing loss of plant and animal species and ecosystem services provided by them. Coffee forest fragment within the Jimma Zone of Ethiopia cannot be expected to be an exception to such scenario. Taking this persistent problem into consideration, we carried out a preliminary survey of bird biodiversity in selected areas of Jimma Zone during a short term bird ringing training held from Sept. 30 to Oct. 20, 2008. The main objective of the survey was to identify and document bird species of Jimma Zone, Southwestern Ethiopia, for further in-debth ornithological studies. Survey data were collected through exhaustive observations in and around 10 coffee forest fragments in Garuke, one fragment in Eladale, one urban area site in Jimma town and in scrubland vegetation around Gilgel Ghibe hydropower reservoir, Jimma Zone, Southwestern Ethiopia. In addition, five mist-nets were employed to capture understory forest birds in two purposively selected coffee forest fragments. Mist nets were opened at 5:50 A.M. and checked every 30 minutes until they were closed at 12:00 A.M. Over 196 bird species were identified during this survey and of these, 41 individuals belonging to 20 species were captured in Garuke and 23 individuals of 9 bird species in Eladale. Montane white-eye (Zosterops poliogastrus) followed by Olive sunbird (Nectarinia olivacea), Abyssinian slaty-flycatcher (Melaenornis chocolatinus) and Rupell&#x2019;s robinchat (Cossypha semirufa) were the most frequently captured bird species. Of the sites surveyed, Gilgel Ghibe hydropower reservoir had strikingly highest bird species diversity. We approached the reservoir almost in a constant site near Bulbul Kebele (the smallest administrative unit in Ethiopia) and recorded over 115 bird species within about 300 meters distance! We learnt that this area was an important and most appropriate site to see a number of migrant and resident species as well as to undertake future bird ringing activities. We believe that the result of this survey will contribute much for the preparation of a comprehensive bird species checklist for Jimma Zone that could serve as important baseline information for more focused future ornithological investigations in the area so as to promote bird conservation through ecotourism activities and improve the livelihood of local people

Crop-specific and single-species mycorrhizal inoculation is the best approach to improve crop growth in controlled environments

International audienceAbstractArbuscular mycorrhizal fungi are root symbionts that play a key role in crop growth. A systematic quantitative analysis of the response of crops to arbuscular mycorrhizal inoculation, however, remains to be done. Additionally, little is known regarding the role of mycorrhizal specificity and the diversity of the inoculum on crop growth. Therefore, we collected data from 115 inoculation studies, including 435 experiments. We then used meta-analysis to examine the effect of crop identity, arbuscular mycorrhizal fungus identity, and mycorrhizal diversity on crop biomass increase, following inoculation. Our results show that total crop biomass was on average 34.9 % higher in inoculated versus non-inoculated plants. We found that specific combinations of arbuscular mycorrhizal fungus genera and host plant families were more beneficial for growth promotion as compared to other combinations. Moreover, a single-species inoculum increased crop growth response on average by 41.2 % compared to a multi-species inoculum. Overall, our findings show that a broad range of crops highly benefit from the inoculation with arbuscular mycorrhizal fungi. They also strongly suggest that selecting specific arbuscular mycorrhizal taxa for specific crops is the most promising approach to enhance crop growth. There is no “one-size-fits-all” arbuscular mycorrhizal fungus. Finally, and at least in stable and controlled environments, inoculation with a single arbuscular mycorrhizal species is more effective, compared to inoculation with a mixture of different arbuscular mycorrhizal taxa. This may be explained by fungi superior in extraradical growth, but less beneficial to the host, that outcompete the more mutualistic fungi. Therefore, it may be beneficial to maintain a high dominance of one beneficial arbuscular mycorrhizal taxon in simplified agricultural systems

Habitat fragmentation affects climate adaptation in a forest herb

Climate change and increased drought frequencies are expected to have a major impact on forest herb persistence. The adaptive capacity of forest herbs will depend on their long standing imprints of local adaptation and phenotypic plasticity. To evaluate how local adaptation to habitat fragmentation affects climate adaptation we quantified a wide range of traits in a common garden experiment of Primula elatior. Specifically, we disentangled the relative contribution of climate, habitat fragmentation, and drought stress on trait variation of the germination lag time, germination rate, growth rate, root:shoot ratio, specific leaf area, stomatal density, glandular trichome density, flower phenology and flower investment. To further evaluate mating shifts we quantified flower colour adaptations, herkogamy, and self-incompatibility. Local adaptations in P. elatior displayed strong alignment with climate along its range. Northern populations displayed a reduced establishment and competitive potential, while southern populations displayed a high sensitivity to increased drought stress under climate change. Habitat fragmentation resulted in the evolutionary breakdown of reciprocal herkogamy, and a biochemical self-compatibility in S morphs. Furthermore, a significant differentiation of the flower colour attraction patterns and a strongly reduced flowering investment was observed in the south of the range. Fragmented populations also displayed a strategic developmental focus on survival and stress resistance. The interaction between local adaptation to climate and habitat fragmentation could have far reaching effects on (meta-)population dynamics under climate change and could limit the successful application of assisted migration strategies

Biogeographical patterns of legume-nodulating <i>Burkholderia </i>spp.:from African Fynbos to continental scales

UNLABELLED: Rhizobia of the genus Burkholderia have large-scale distribution ranges and are usually associated with South African papilionoid and South American mimosoid legumes, yet little is known about their genetic structuring at either local or global geographic scales. To understand variation at different spatial scales, from individual legumes in the fynbos (South Africa) to a global context, we analyzed chromosomal (16S rRNA, recA) and symbiosis (nifH, nodA, nodC) gene sequences. We showed that the global diversity of nodulation genes is generally grouped according to the South African papilionoid or South American mimosoid subfamilies, whereas chromosomal sequence data were unrelated to biogeography. While nodulation genes are structured on a continental scale, a geographic or host-specific distribution pattern was not detected in the fynbos region. In host range experiments, symbiotic promiscuity of Burkholderia tuberum STM678(T) and B phymatum STM815(T) was discovered in selected fynbos species. Finally, a greenhouse experiment was undertaken to assess the ability of mimosoid (Mimosa pudica) and papilionoid (Dipogon lignosus, Indigofera filifolia, Macroptilium atropurpureum, and Podalyria calyptrata) species to nodulate in South African (fynbos) and Malawian (savanna) soils. While the Burkholderia-philous fynbos legumes (D lignosus, I filifolia, and P calyptrata) nodulated only in their native soils, the invasive neotropical species M pudica did not develop nodules in the African soils. The fynbos soil, notably rich in Burkholderia, seems to retain nodulation genes compatible with the local papilionoid legume flora but is incapable of nodulating mimosoid legumes that have their center of diversity in South America. IMPORTANCE: This study is the most comprehensive phylogenetic assessment of root-nodulating Burkholderia and investigated biogeographic and host-related patterns of the legume-rhizobial symbiosis in the South African fynbos biome, as well as at global scales, including native species from the South American Caatinga and Cerrado biomes. While a global investigation of the rhizobial diversity revealed distinct nodulation and nitrogen fixation genes among South African and South American legumes, regionally distributed species in the Cape region were unrelated to geographic and host factors.status: publishe

Typology of the woody plant communities of the Ethiopian Nech Sar National Park and an assessment of vegetation-environment relations and human disturbance impacts

Background and aims – Deforestation and forest degradation have hugely affected the Southern Ethiopian Rift Valley, jeopardizing biodiversity conservation and ecosystem service provisioning. Quantifying the impacts of human activities on the remaining woody plant communities and recognizing vegetation–environment relationships provide the basis for targeted conservation and rehabilitation.Material and methods – The study was performed in the Nech Sar National Park (NSNP). Based on a large systematic vegetation survey of 104 plots, we quantified the woody vegetation composition, and we provided a vegetation classification based on Non Metric Multidimensional Scaling, cluster analysis and indicator species analysis. Furthermore, we evaluated vegetation – environment relationships and the effects of human disturbance on community composition and woody plant species richness and diversity.Key results – Our analyses revealed three very distinct woody vegetation types (Acacia mellifera-Combretum aculeatum; Lecaniodiscus fraxinifolius-Deinbollia kilimandscharica and Acacia polyacantha-Ficus sycomorus) which were significantly differentiated by soil pH, electrical conductivity, available soil phosphorus and organic matter, and by elevation. Human disturbance, as quantified by a compound Human Disturbance Index (HDI) significantly affected community composition, species richness and diversity, and was significantly positively correlated with species richness and diversity. The latter is likely due to intermediate levels of disturbance and encroachment of disturbance affiliated shrubs such as Dichrostachys cinerea, Lantana camara, and Acalypha fruticosa. Furthermore, the demographic structure of key woody species such as Acacia polyacantha, Acacia tortilis, Balanites aegyptiaca, Diospyros abyssinica, Lecaniodiscus fraxinifolius and Terminalia brownii, showed impacts of human disturbance.Conclusion – Our results provide a baseline for further conservation actions in the NSNP which should be differentially targeted on the different plant community types. Overall, human disturbance seems not to have resulted yet in species richness declines, although it has started to affect the integrity of the delineated vegetation types and resulted in small scale succession