Life history shifts and alterations in the early development of parasitic wasps

Summary

In insects, the regulation of embryonic development has been intensively studied in model species like Drosophila melanogaster. Previous comparative studies have suggested that the developmental processes documented in Drosophila well describe embryogenesis of holometabolous insects generally. However, there have been few attempts to take into account how life history has influenced insect embryogenesis or to characterize early development of species with life histories fundamentally different from flies. Our studies of advanced insects in the order Hymenoptera suggest that punctuated shifts in life history can profoundly influence these events. In particular, alterations associated with the evolution of endoparasitism argue that departures from the fly paradigm may occur commonly among insects that develop under conditions different from typical terrestrial species.     

Putative local adaptations modulate the interactions of the carnivorous plant Drosera uniflora Willd (1809) (Droseraceae) with cushion and shrub nurse plants

Cushion and shrub plants are typical high mountain nurse plants. In Magellanic tundras of the Cordillera del Sarao on the coast of Chile, the carnivorous plant Drosera uniflora grows in association with cushions of Donatia fascicularis and the shrubs Chusquea montana var. nigricans and Lepidothamnus fonkii. The different microhabitats for recruitment, in addition to the limited gene flow of D. uniflora, enable us to hypothesise that this plant manifests putative local adaptations, expressed in seed germination and population abundance. Our aim was to evaluate the local adaptation of D. uniflora to cushion and shrub microhabitats by estimating germination and abundance. Local adaptation of seed germination was determined by means of reciprocal transplant experiments. Abundance was determined in small plots located inside, on the edge and outside the nurse plants. Seed origin and growth substrate play a decisive role in D. uniflora germination. Seeds that originate from cushions plant habitat and germinate in the same substrate do so in greater numbers than when those which originate from shrubby habitats. Conversely, seeds that originate from shrubby habitat and germinate in the same substrate do not exhibit significant differences. Abundance was always greater inside than outside of the nurse plants. We concluded that availability and quality of different microhabitats for seed germination and recruitment, together with a limited gene flow, would trigger putative local adaptations in D. uniflora, modulating a long history of interactions with the plants that act as nurse plants.     

Chromosome‐level genome assembly for the horned‐gall aphid provides insights into interactions between gall‐making insect and its host plant

The aphid Schlechtendalia chinensis is an economically important insect that can induce horned galls, which are valuable for the medicinal and chemical industries. Up to now, more than twenty aphid genomes have been reported. Most of the sequenced genomes are derived from free‐living aphids. Here, we generated a high‐quality genome assembly from a galling aphid. The final genome assembly is 271.52 Mb, representing one of the smallest sequenced genomes of aphids. The genome assembly is based on contig and scaffold N50 values of the genome sequence are 3.77 Mb and 20.41 Mb, respectively. Nine‐seven percent of the assembled sequences was anchored onto 13 chromosomes. Based on BUSCO analysis, the assembly involved 96.9% of conserved arthropod and 98.5% of the conserved Hemiptera single‐copy orthologous genes. A total of 14,089 protein‐coding genes were predicted. Phylogenetic analysis revealed that S. chinensis diverged from the common ancestor of Eriosoma lanigerum approximately 57 million years ago (MYA). In addition, 35 genes encoding salivary gland proteins showed differentially when S. chinensis forms a gall, suggesting they have potential roles in gall formation and plant defense suppression. Taken together, this high‐quality S. chinensis genome assembly and annotation provide a solid genetic foundation for future research to reveal the mechanism of gall formation and to explore the interaction between aphids and their host plants.     

The Chimonanthus salicifolius genome provides insight into magnoliid evolution and flavonoid biosynthesis

Chimonanthus salicifolius, a member of the Calycanthaceae of magnoliids, is one of the most famous medicinal plants in Eastern China. Here, we report a chromosome‐level genome assembly of C. salicifolius, comprising 820.1 Mb of genomic sequence with a contig N50 of 2.3 Mb and containing 36 651 annotated protein‐coding genes. Phylogenetic analyses revealed that magnoliids were sister to the eudicots. Two rounds of ancient whole‐genome duplication were inferred in the C. salicifolious genome. One is shared by Calycanthaceae after its divergence with Lauraceae, and the other is in the ancestry of Magnoliales and Laurales. Notably, long genes with > 20 kb in length were much more prevalent in the magnoliid genomes compared with other angiosperms, which could be caused by the length expansion of introns inserted by transposon elements. Homologous genes within the flavonoid pathway for C. salicifolius were identified, and correlation of the gene expression and the contents of flavonoid metabolites revealed potential critical genes involved in flavonoids biosynthesis. This study not only provides an additional whole‐genome sequence from the magnoliids, but also opens the door to functional genomic research and molecular breeding of C. salicifolius.     

The hypothesis of sympatric speciation as the dominant generator of endemism in a global hotspot of biodiversity

Allopatric or sympatric speciation influence the degree to which closely related species coexist in different manners, altering the patterns of phylogenetic structure and turnover among and between communities. The objective of this study was to examine whether phylogenetic community structure and turnover in the Brazilian Atlantic Forest permit conclusions about the dominant process for the formation of extant angiosperm richness of tree species. Therefore, we analyzed phylogenetic community structure (MPD, MNTD) as well as taxonomic (Jaccard similarity) and phylogenetic turnover (betaMPD, betaMNTD) among and between 49 tree communities distributed among three different habitat types. Mean annual precipitation and mean annual temperature in each survey area were estimated. Phylogenetic community structure does not differ between habitat types, although MPD reduces with mean annual temperature. Jaccard similarity decreases and betaMNTD increases with spatial distance and environmental differences between study sites. Spatial distance explains the largest portions of variance in the data, indicating dispersal limitation and the spatial aggregation of recently formed taxa, as betaMNTD is related to more recent evolutionary events. betaMPD, that is related to deep evolutionary splits, shows no spatial or environmental pattern, indicating that older clades are equally distributed across the Brazilian Atlantic Forest. While similarity pattern indicates dispersal limitations, the spatial turnover of betaMNTD is consistent with a high degree of sympatric speciation generating extant diversity and endemism in the Brazilian Atlantic Forest. More comprehensive approaches are necessary to reduce spatial sampling bias, uncertainties regarding angiosperm diversification patterns and confirm sympatric speciation as the dominant generator for the formation of extant species diversity in the Brazilian Atlantic Forest.     

哺乳动物毛色形成机制与影响因素

哺乳动物拥有丰富多彩的毛色,对于多种多样的动物毛色,影响其形成的可能原因较多,遗传物质与环境的相互作用不可忽视。本文针对调控黑色素细胞形成及褐黑色素、真黑色素合成的相关基因,分析了哺乳动物毛色形成的可能机制,并对研究不同毛色动物的同种动物遗传差异的方法进行了讨论。     

Spatial heterogeneity of wind forcing: application to artificial reef functioning influenced by the circulation in the Bay of Marseilles, France

In the frame of the largest French project of artificial production reefs, initiated by the city of Marseilles in 2001, the present study aimed at describing the hydrodynamic pattern of the coastal area considered, by the use of a 3D numerical modelling. Results were local wind statistics, bottom current fields and drifting particle maps. The knowledge of the hydrodynamic connexions between particle (such as larvae) sources or targeted areas linked to the reefs, allows us to explain the success or failure of the reefs' colonizing. Moreover, the study confirms the wind spatial variability and demonstrates the error resulting from the use of an average but locally absent wind direction.     

Changes of Endogenous Hormone Contents During Floral Bud and Vegetative Bud Differentiation in Thin Cell Layer Culture of Cichorium intybus L. Explant

The sectioned thin cell layers (TCL) of flower stalk of Cichorium intybus L. were cultured in MS medium supplemented with NAA and BA or IAA and BA where floral and vegetative buds were developed from the explant. Endogenous IAA, DHZ+DHZR, iPA increased significantly during the floral bud formation, while Z+ZR remained changed. The levels of cytokinins, DHZ +DHZR, iPA, and Z-f-ZR all increased significantly during the vegetative bud formation, however IAA level was reduced during the first 7 days of culture and increased to two-thirds of initial values on the day when the bud primordia were formed. The results suggested that the initiation of floral buds was associated with a high IAA/CTK ratio, whereas the induction of vegetative bud differentiation was related to a low IAA/CTK ratio.