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Microorganisms comprise the majority of earth's biodiversity and are integral to biosphere processes. Biological invasions are no exception to this trend. The success of introduced macroorganisms can be deeply influenced by diverse microorganisms (bacteria, virus, fungus and protozoa) occupying the whole range of species interaction outcomes, from parasitism to obligate mutualism. This large range of interactions, often coupled with complex historical and introduction events, can result in a wide variety of ecological dynamics. In this chapter, we review different situations in which microorganisms affect biological invasions. First, we consider outcomes of microorganism loss during the introduction of alien species. Second, we discuss positive effects of microorganisms on the invasiveness of their exotic hosts. Third, we examine the influence of microorganisms hosted by native species on the success of introduced species. Finally, in an applied perspective, we envisage how microorganisms can be used (i) to better decipher invasion processes and (ii) as biological control agents. [ABSTRACT FROM AUTHOR]

Examines the microsatellite loci in the neotropical tree species, Vouacapoua americana. Contributing factors to genetic diversity; Number of alleles per locus; Annealing temperature; Estimate heterozygosity.

Plants are daily challenged by multiple abiotic and biotic stresses. A major biotic constraint corresponds to competition with other plant species. Although plants simultaneously interact with multiple neighboring species throughout their life cycle, there is still very limited information about the genetics of the competitive response in the context of plurispecific interactions. Using a local mapping population of Arabidopsis thaliana , we set up a genome wide association study (GWAS) to estimate the extent of genetic variation of competitive response in 12 plant species assemblages, based on three competitor species ( Poa annua , Stellaria media , and Veronica arvensis ). Based on five phenotypic traits, we detected strong crossing reaction norms not only between the three bispecific neighborhoods but also among the plurispecific neighborhoods. The genetic architecture of competitive response was highly dependent on the identity and the relative abundance of the neighboring species. In addition, most of the enriched biological processes underlying competitive responses largely differ among neighborhoods. While the RNA related processes might confer a broad range response toolkit for multiple traits in diverse neighborhoods, some processes, such as signaling and transport, might play a specific role in particular assemblages. Altogether, our results suggest that plants can integrate and respond to different species assemblages depending on the identity and number of each neighboring species, through a large range of candidate genes associated with diverse and unexpected processes leading to developmental and stress responses., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Libourel, Baron, Lenglet, Amsellem, Roby and Roux.)

In the version of this Article previously published, there was a typographical error ('4' instead of '2') in the equations relating F ST and effective population size (N e ) in the Methods section 'Genome-wide scan for selection based on temporal differentiation'. The correct equations are given below.[Formula: see text] [Formula: see text].

Rapid phenotypic evolution of quantitative traits can occur within years, but its underlying genetic architecture remains uncharacterized. Here we test the theoretical prediction that genes with intermediate pleiotropy drive adaptive evolution in nature. Through a resurrection experiment, we grew Arabidopsis thaliana accessions collected across an 8-year period in six micro-habitats representative of that local population. We then used genome-wide association mapping to identify the single-nucleotide polymorphisms (SNPs) associated with evolved and unevolved traits in each micro-habitat. Finally, we performed a selection scan by testing for temporal differentiation in these SNPs. Phenotypic evolution was consistent across micro-habitats, but its associated genetic bases were largely distinct. Adaptive evolutionary change was most strongly driven by a small number of quantitative trait loci (QTLs) with intermediate degrees of pleiotropy; this pleiotropy was synergistic with the per-trait effect size of the SNPs, increasing with the degree of pleiotropy. In addition, weak selection was detected for frequent micro-habitat-specific QTLs that shape single traits. In this population, A. thaliana probably responded to local warming and increased competition, in part mediated by central regulators of flowering time. This genetic architecture, which includes both synergistic pleiotropic QTLs and distinct QTLs within particular micro-habitats, enables rapid phenotypic evolution while still maintaining genetic variation in wild populations.

We compared the reproductive system of Rubus alceifolius in its native range in Southeast Asia, in Madagascar, where the plant was introduced apparently some centuries ago, and in La Réunion, an Indian Ocean island onto which R. alceifolius was introduced (from Madagascan source populations) around 1850. While tetraploidy makes it impossible to analyze variation in R. alceifolius using classical methods of population genetics, both the patterns of genetic diversity (as revealed by AFLP [amplified fragment length polymorphism] markers) and differences between half-sib progeny and their maternal parents (revealed by microsatellite markers) show that in the plant's native range in southeast Asia, seeds are produced sexually. In contrast, in Madagascar sexual reproduction cannot alone account for the genetic patterns observed with microsatellite markers. Over 85% of the half-sib progeny resulting from open pollination gave multilocus genotypes identical to those of their respective maternal parents, despite the fact that the latter had alleles that were rare in the population. The other progeny differed in having an allele with one motif more or less than that of the maternal parent. Seeds thus appear to be produced mostly or exclusively by apomixis in Madagascar. We present findings suggesting that Madagascan populations result from hybridization of introduced R. alceifolius and native populations of R. roridus, a closely related species of Rubus subgenus Malachobatus, and suggest that apomixis was a consequence of this hybridization. In Reunionese populations of R. alceifolius (derived from Madagascan populations), seeds obtained in controlled pollination experiments were all genetically identical to maternal parents. While genetic variation (microsatellite markers) in Reunionese populations was low, it was sufficient to allow us to demonstrate that seeds could not have resulted from fertilization by the pollen donors chosen for controlled pollinations, or from autogamy, and were produced exclusively by apomixis.