Selection on fruit traits is mediated by the interplay between frugivorous birds, fruit flies, parasitoid wasps and seed-dispersing ants.

Every organism on Earth must cope with a multitude of species interactions both directly and indirectly throughout its life cycle. However, how selection from multiple species occupying different trophic levels affects diffuse mutualisms has received little attention. As a result, how a given species amalgamates the combined effects of selection from multiple mutualists and antagonists to enhance its own fitness remains little understood. We investigated how multispecies interactions (frugivorous birds, ants, fruit flies and parasitoid wasps) generate selection on fruit traits in a seed dispersal mutualism. We used structural equation models to assess whether seed dispersers (frugivorous birds and ants) exerted phenotypic selection on fruit and seed traits in the spiny hackberry (Celtis ehrenbergiana), a fleshy-fruited tree, and how these selection regimes were influenced by fruit fly infestation and wasp parasitoidism levels. Birds exerted negative correlational selection on the combination of fruit crop size and mean seed weight, favouring either large crops with small seeds or small crops with large seeds. Parasitoids selected plants with higher fruit fly infestation levels, and fruit flies exerted positive directional selection on fruit size, which was positively correlated with seed weight. Therefore, higher parasitoidism indirectly correlated with higher plant fitness through increased bird fruit removal. In addition, ants exerted negative directional selection on mean seed weight. Our results show that strong selection on phenotypic traits may still arise in perceived diffuse species interactions. Overall, we emphasize the need to consider diverse direct and indirect partners to achieve a better understanding of the mechanisms driving phenotypic trait evolution in multispecies interactions.

Chloroplast analysis of Zelkova schneideriana (Ulmaceae): genetic diversity, population structure, and conservation implications.

Zelkova schneideriana is endemic to China and belongs to the Ulmaceae. It is listed as a Near Threatened species in the China Biodiversity Red Data Book. We conducted a phylogeographical study of two chloroplast regions (psbA-trnH and trnG-trnM) in several Chinese Z. schneideriana populations, in order to examine the genetic diversity, population structure, and evolutionary history of the species. In all, 10 haplotypes were detected. The population from Sangzhi, Hunan, had the highest nucleotide diversity (π = 0.00653) and haplotype diversity (HD = 1.000), and should be considered the most suitable population to be protected under an in situ conservation strategy. Seed collections from as many individuals as possible in other populations would preserve the genetic diversity of Z. schneideriana.

Analysis of nuclear microsatellites reveals limited differentiation between Colchic and Hyrcanian populations of the wind-pollinated relict tree Zelkova carpinifolia (Ulmaceae).

UNLABELLED: • PREMISE OF THE STUDY: The Caucasus represents one of the world's biodiversity hotspots and includes the climatic refugia Hyrcan on the southern coast of the Caspian Sea and Colchis on the eastern coast of the Black Sea, where different species survived during the Quaternary climatic oscillations. We evaluated the genetic diversity of the relict tree Zelkova carpinifolia shared between the two refugia and distributed throughout the Caucasus and adjacent areas.• METHODS: Specimens were collected from 30 geographical sites in Azerbaijan, Georgia, Iran, and Turkey and screened for variability at eight nuclear microsatellite loci. The genetic diversity among and within populations was assessed using a set of statistical measures.• KEY RESULTS: We detected 379 different genotypes from a total of 495 individuals with varying degrees of clonal reproduction at the different sites. Low to intermediate levels of genetic diversity were observed at all sites, and strong differentiation between sampling sites was absent. In addition, we observed no clear genetic differentiation between the Colchis and Hyrcan. Bayesian clustering of the genotypes revealed three populations with high levels of admixture between the sampling sites.• CONCLUSIONS: The lack of strong genetic structure of studied populations of Z. carpinifolia contrasts with a previous study based on chloroplast markers and suggests that long-distance pollen dispersal is an important factor of gene flow among populations of Z. carpinifolia. The present study does not reveal any particular site with particularly isolated genotypes that would deserve more attention for conservation purposes than others, although some sites should be considered for further investigation.

Efficient development of polymorphic microsatellite loci for Pteroceltis tatarinowii (Ulmaceae).

Pteroceltis tatarinowii (Ulmaceae) is a scientifically and economically important temperate deciduous tree that is endemic to China. In the present study, 12 P. tatarinowii polymorphic microsatellite loci were developed using the tailed primer-M13-simple sequence repeats (TP-M13-SSR) biotin-capture method. The number of alleles per locus ranged from 2 to 10, with an average of 6.58. The observed and expected heterozygosity ranged from 0.208 to 0.958 and from 0.198 to 0.858, with average values of 0.703 and 0.710, respectively. The markers isolated in this study represent a favorable tool for further analyses of the population genetic structure and evolutionary history of this relic tree.

Isolation and characterization of polymorphic microsatellite loci from Zelkova schneideriana Hand.-Mazz.

Zelkova schneideriana is a highly valued hardwood species. An improved technique for isolating codominant compound microsatellite markers was used to develop simple sequence repeat markers for Z. schneideriana. A total of 12 microsatellite loci were identified. Overall, the number of alleles per locus ranged from 8-19, with an average of 11.75. Observed heterozygosity and expected heterozygosity values ranged from 0.109-0.709 and 0.832-0.929, respectively. Polymorphic information content is from 0.803-0.915, with an average of 0.854. These markers will be very important for future research related to the genetic diversity, population structure, patterns of gene flow, and mating system of this species.

Genome size estimations on Ulmus minor Mill., Ulmus glabra Huds., and Celtis australis L. using flow cytometry.

The Ulmaceae family is composed of nearly 2000 species widely distributed in the northern hemisphere. Despite their wide distribution area, there are only four native species in the Iberian Peninsula. In this work the genome size of three of those species (ULMUS MINOR, U. GLABRA, and CELTIS AUSTRALIS) was estimated using flow cytometry. The nuclear DNA content of C. AUSTRALIS was estimated as 2.46 +/- 0.061 pg/2C, of U. MINOR as 4.25 +/- 0.158 pg/2C, and of U. GLABRA as 4.37 +/- 0.103 pg/2C of DNA. No statistically significant differences were detected among individuals of the same species. These species revealed to be problematic for flow cytometric analyses, due to the release of mucilaginous compounds into the nuclear suspension. Despite that, the modified protocol here presented ensured high quality analyses (low coefficient of variation and background debris and nuclear fluorescence stability), opening good perspectives on its application to estimate the genome size of species with similar problems.

LysM-type mycorrhizal receptor recruited for rhizobium symbiosis in nonlegume Parasponia.

Rhizobium-root nodule symbiosis is generally considered to be unique for legumes. However, there is one exception, and that is Parasponia. In this nonlegume, the rhizobial nodule symbiosis evolved independently and is, as in legumes, induced by rhizobium Nod factors. We used Parasponia andersonii to identify genetic constraints underlying evolution of Nod factor signaling. Part of the signaling cascade, downstream of Nod factor perception, has been recruited from the more-ancient arbuscular endomycorrhizal symbiosis. However, legume Nod factor receptors that activate this common signaling pathway are not essential for arbuscular endomycorrhizae. Here, we show that in Parasponia a single Nod factor-like receptor is indispensable for both symbiotic interactions. Therefore, we conclude that the Nod factor perception mechanism also is recruited from the widespread endomycorrhizal symbiosis.