Project description:The whitefly Bemisa tabaci is a species complex of more than 31 cryptic species which include some of the most destructive invasive pests of many ornamental and glasshouse crops worldwide. Among them, Middle East-Asia Minor 1 (herein MEAM1) and Mediterranean (herein MED) have invaded many countries around the world and displaced the native whitefly species. However, the molecular differences between invasive and indigenous whiteflies remain largely unknown. The global transcriptional difference between the two invasive whitefly Bemisia tabaci species (MEAM1, MED) and one indigenous whitefly species (Asia II 3) were analyzed using the Illumina sequencing technology.
Project description:The whitefly Bemisa tabaci is a species complex of more than 31 cryptic species which include some of the most destructive invasive pests of many ornamental and glasshouse crops worldwide. Among them, Middle East-Asia Minor 1 (herein MEAM1) and Mediterranean (herein MED) have invaded many countries around the world and displaced the native whitefly species. However, the molecular differences between invasive and indigenous whiteflies remain largely unknown.
Project description:[original Title] Transcriptomic responses to heat-stress in invasive and native blue mussels (genus Mytilus): molecular correlates of invasive success. Invasive species are increasingly prevalent in marine ecosystems worldwide. Although many studies have examined the ecological effects of invasives, little is known about physiological mechanisms that might contribute to invasive success. The mussel Mytilus galloprovincialis, a native of the Mediterranean Sea, is a successful invader on the central and southern coasts of California, where it has largely displaced the native congener, Mytilus trossulus. It has been previously shown that thermal responses of several physiological traits may underlie the capacity of M. galloprovincialis to out-compete M. trossulus in warm habitats. To elucidate possible differences in stress-induced gene expression between these congeners, we developed an oligonucleotide microarray with 8,874 probes representing 4,488 different genes that recognized mRNAs of both species. In acute heat-stress experiments, 1,531 of these genes showed temperature-dependent changes in gene expression that were highly similar in the two congeners. In contrast, 96 genes showed species-specific responses to heat-stress, functionally characterized by their involvement in oxidative stress, proteolysis, energy metabolism, ion transport, cell signaling, and cytoskeletal reorganization. The gene that showed the biggest difference between the species was the gene for the molecular chaperone small heat shock protein 24, which was highly induced in M. galloprovincialis and showed only a small change in M. trossulus. These different responses to acute heat-stress may help to explain—and predict—the invasive success of M. galloprovincialis in a warming world.
Project description:Hybridization between Cottus rhenanus and C. perifretum has resulted in an evolutionary young hybrid lineage of invasive Cottus that has colonized a new habitat where the parental species are not found (Nolte et al. 2005; Proc. R. Soc. B 272: 2379–2387). This CGH array was designed to screen for copy number variation among Cottus species and to find gene duplicates that are unique to the hybrid lineage (see also Dennenmoser et al. 2017; Copy number increases of transposable elements and protein coding genes in an invasive fish of hybrid origin).
Project description:The invasive marine mussel Mytilus galloprovincialis has displaced the native congener Mytilus trossulus from central and southern California, but the native species remains dominant at more northerly sites that have high levels of freshwater input. To determine the extent to which interspecific differences in physiological tolerance to low salinity might explain limits to the invasive species’ biogeography, we used an oligonucleotide microarray to compare the transcriptional responses of these two species to an acute decrease in salinity. Among 6,777 genes on the microarray, 117 genes showed significant changes that were similar between species, and 12 genes showed significant species-specific responses to salinity stress. Osmoregulation and cell cycle control were important aspects of the shared transcriptomic response to salinity stress, whereas the genes with species-specific expression patterns were involved in mRNA splicing, polyamine synthesis, exocytosis, translation, cell adhesion, and cell signaling. Forty-five genes that changed expression significantly during salinity stress also changed expression during heat stress, but the direction of change in expression was typically opposite for the two forms of stress. These results (i) provide insights into the role of changes in gene expression in establishing physiological tolerance to acute decreases in salinity, and (ii) indicate that transcriptomic differences between M. galloprovincialis and M. trossulus in response to salinity stress are subtle and involve only a minor fraction of the overall suite of gene regulatory responses.
Project description:European sculpins (Cottus) harbor an example of a recent hybrid speciation event, which entails the invasion of a new habitat by the hybrid species. We compare the transcriptomes of both parental species and the hybrid species to understand how they differ. F2 crosses between the parent species are compared to the hybrid species and its parent species to identify unique patterns of the hybrid species due to the initial hybridization process or respectively to other processes. See the accompanying publication (Czypionka et al. 2011.Transcriptome changes after genome wide admixture in invasive sculpins Molecular Ecology no doi yet) for more information.
Project description:Upon colonizing new habitats invasive species face a series of new selection pressures as a result of changing abiotic conditions and novel biotic interactions with native species. These new selection pressures can be accommodated by different mechanism that act on different levels and across different time scales: 1) By changing transcriptomic profiles species can react by plasticity within individual physiological limitations. 2) Invasive populations can adapt by fixing beneficial genetic variants in response to the newly encountered selection pressures. Here, we compare the genomic and transcriptomic landscapes of two independent invasions of the Pacific Oyster Crassostrea gigas into the North Sea. In detail, we combine high density full genome resequencing and low density ddRAD on the genomic level with RNAseq on the transcriptomic level to reveal outlier loci (SNPs) indicative of adaptation, as well as transcriptomic profiles from a translocation experiment to show immediate physiological reactions. The low congruence between differentially regulated genes and outlier loci indicates that different processes act on the different time scales. By contrasting population outlier loci and population specific transcriptomic profiles we can thus identify relevant processes acting during different phases of the invasive process, which will allow to take a glimpse at the traits and processes characterizing successful invasions.