Adaptation is the central feature and leading explanation for the evolutionary diversification of life. Adaptation is also notoriously difficult to study in nature, owing to its complexity and logistically prohibitive timescale. We leverage extensive contemporary and historical collections of Ambrosia artemisiifolia—an aggressively invasive weed and primary cause of pollen-induced hayfever—to track the phenotypic and genetic causes of adaptation across its native and invasive ranges in North America and Europe, respectively. Large haploblocks—indicative of chromosomal inversions—contain a disproportionate share of genomic regions conferring parallel adaptation between ranges (18%), are associated with rapidly adapting traits, and exhibit dramatic frequency shifts over space and time. These results highlight the importance of structural and large-effect variants in rapid adaptation, which have been critical to A. artemisiifolia’s global spread.One Sentence SummaryParallel evolution between native and invasive ranges of Ambrosia artemisiifolia is aided by putative chromosomal inversions.

Adaptation is the central feature and leading explanation for the evolutionary diversification of life. Adaptation is also notoriously difficult to study in nature, owing to its complexity and logistically prohibitive timescale. Here, we leverage extensive contemporary and historical collections of Ambrosia artemisiifolia—an aggressively invasive weed and primary cause of pollen-induced hayfever—to track the phenotypic and genetic causes of recent local adaptation across its native and invasive ranges in North America and Europe, respectively. Large haploblocks—indicative of chromosomal inversions—contain a disproportionate share (26%) of genomic regions conferring parallel adaptation to local climates between ranges, are associated with rapidly adapting traits, and exhibit dramatic frequency shifts over space and time. These results highlight the importance of large-effect standing variants in rapid adaptation, which have been critical to A. artemisiifolia’s global spread across vast climatic gradients.

Common ragweed (Ambrosia artemisiifolia L.) is an annual Asteraceae species native to North America which is highly invasive across Europe and has harmful impacts, especially on human health and agriculture. Besides its wide ecological range, particularly its high reproductive power by seeds is promoting its spread to various habitats and regions. To prevent further spread and to control the plant, the European Commission funded projects and COST-Actions involving scientists from all over Europe. A joint trial was set up comprising eight different laboratories from Europe to study seed viability variation in different seed samples. Three different testing methods (viability test with 2,3,5-triphenyltetrazolium chloride (TTC), a germination test combined with a subsequent TTC test and a crush test) were tested within the EU-COST-Action SMARTER network to four different seed origins. The viability test results from different laboratories were compared for variation amongst tests and laboratories. The main aim was to optimise the reliability of testing procedures, but results revealed not only significant effects of seed origin and seed age on seed viability, but also considerable differences between the output of the individual testing methods and furthermore between laboratories. Due to these significant differences in the results of the testing labs, additionally a second test was set up. Twelve Austrian ragweed populations were used for TTC testing to obtain a precise adjustment of the testing method as well as a tight guideline for interpreting the results, particularly for the TTC state “intermediate” since a proper classification of TTC-intermediate coloured seeds is still a challenge when determining viability rates.

Hemp (Cannabis sativa L.) was one of the earliest domesticated plant species. Biological classification (taxonomy or systematization) manifests evolutional relationships between taxons according to trait similarities. When it comes to taxonomy, hemp is one of the most controversial plant species due to significant effects of environmental conditions on hemp phenology and expression of quantitative traits as well as different levels of gender expression observed in hemp plants. Controversial taxonomy of hemp has gone through several phases throughout history. The attitude on the number of species within the genus Cannabis and the criteria used in taxonomic units division were under dispute. Initially focused on morphological characteristics and geographical origin, the approach was greatly amended by the development of molecular and biochemical techniques. The main cause of taxonomic uncertainties is the inbreeding ability of all wild Cannabis populations, resulting in continual variability of quantitative traits. The aim of the paper is to review the history of Cannabis classification including different approaches to this scientific issue.

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