Antoine de Jussieu

The genetic composition of founding populations is likely to play a key role in determining invasion success. Individual genotypes may differ in habitat preference and environmental tolerance, so their ability to colonize novel environments can be highly variable. Despite the importance of genetic variation on invasion success, its influence on the potential distribution of invaders is rarely investigated. Here, we integrate population genomics and ecological niche models (ENMs) into a single framework to predict the distribution of globally invasive common ragweed (Ambrosia artemisiifolia) in Australia. We identified three genetic clusters for ragweed and used these to construct cluster‐specific ENMs and characterize within‐species niche differentiation. The potential range of ragweed in Australia depended on the genetic composition and continent of origin of the introduced population. Invaders originating from warmer, wetter climates had a broader potential distribution than those from cooler, drier ones. By quantifying this change, we identified source populations most likely to expand the ragweed distribution. As prevention remains the most effective method of invasive species management, our work provides a valuable way of ranking the threat posed by different populations to better inform management decisions.

Determining whether the climatic ecological niche of an invasive alien plant is similar to that of the niche occupied by its native population (ecological niche conservatism) is essential for predicting the plant invasion process. Ragweed (Ambrosia artemisiifolia L.) usually poses serious threats to human health, agriculture, and ecosystems within its newly occupied range. We calculated the overlap, stability, unfilling, and expansion of ragweed’s climatic ecological niche using principal component analysis and performed ecological niche hypothesis testing. The current and potential distribution of A. artemisiifolia was mapped by ecological niche models to identify areas in China with the highest potential risk of A. artemisiifolia invasion. The high ecological niche stability indicates that A. artemisiifolia is ecologically conservative during the invasion. Ecological niche expansion (expansion = 0.407) occurred only in South America. In addition, the difference between the climatic and native niches of the invasive populations is mainly the result of unpopulated niches. The ecological niche model suggests that southwest China, which has not been invaded by A. artemisiifolia, faces an elevated risk of invasion. Although A. artemisiifolia occupies a climatic niche distinct from native populations, the climatic niche of the invasive population is only a subset of the native niche. The difference in climatic conditions is the main factor leading to the ecological niche expansion of A. artemisiifolia during the invasion. Additionally, human activities play a substantial role in the expansion of A. artemisiifolia. Alterations in the A. artemisiifolia niche would help explain why this species is so invasive in China.

Abstract. Artemisia, along with Chenopodiaceae, is the dominant component growing in the desert and dry grassland of the Northern Hemisphere. Artemisia pollen with its high productivity, wide distribution, and easy identification is usually regarded as an eco-indicator for assessing aridity and distinguishing grassland from desert vegetation in terms of the pollen relative abundance ratio of Chenopodiaceae/Artemisia (C/A). Nevertheless, divergent opinions on the degree of aridity evaluated by Artemisia pollen have been circulating in the palynological community for a long time. To solve the confusion, we first selected 36 species from nine clades and three outgroups of Artemisia based on the phylogenetic framework, which attempts to cover the maximum range of pollen morphological variation. Then, sampling, experiments, photography, and measurements were taken using standard methods. Here, we present pollen datasets containing 4018 original pollen photographs, 9360 pollen morphological trait measurements, information on 30 858 source plant occurrences, and corresponding environmental factors. Hierarchical cluster analysis on pollen morphological traits was carried out to subdivide Artemisia pollen into three types. When plotting the three pollen types of Artemisia onto the global terrestrial biomes, different pollen types of Artemisia were found to have different habitat ranges. These findings change the traditional concept of Artemisia being restricted to arid and semi-arid environments. The data framework that we designed is open and expandable for new pollen data of Artemisia worldwide. In the future, linking pollen morphology with habitat via these pollen datasets will create additional knowledge that will increase the resolution of the ecological environment in the geological past. The Artemisia pollen datasets are freely available at Zenodo (https://doi.org/10.5281/zenodo.6900308; Lu et al., 2022).

В ходе экспедиционных исследований уточнена современная фактическая граница натурализации Аmbrosia artemisiifolia на Европейской территории России. Эта граница проходит по югу Брянской, Курской и Саратовской, северу Воронежской областей. Общая протяжённость экспедиционных маршрутов составила около 8900 км, количество обследованных точек – 777. В целях выявления потенциала дальнейшего продвижения вида на север проведён сравнительный эколого-географический анализ и моделирование распространения амброзии на севере её вторичного ареала на Европейской территории России и первичного – в Канаде. Выявлено, что основным фактором, лимитирующим продвижение вида на север, служит недостаточная теплообеспеченность периода созревания семян. Для определения эколого-географической ниши амброзии была составлена глобальная карта распределения сумм активных температур с порогом выше 10 °С за период от даты перехода длины дня через 14 часов после летнего солнцестояния до устойчивого перехода осенних температур через 0 °С (САТфп). Было определено значение САТфп на самых северных точках натурализации Аmbrosia artemisiifolia на Европейской территории России и в Канаде. Сравнение эколого-географических границ по фактору теплообеспеченности на Европейской территории России и в Канаде показало, что реализованная видом эколого-географическая ниша на Североамериканском континенте в настоящее время в целом шире, чем на Европейской территории России. Рассмотрены возможные причины, по которым амброзия не освоила всю потенциальную экологическую нишу на Европейской территории России, сделаны предположения о возможности дальнейшего продвижения вида на север. Амброзия по фактору теплообеспеченности на Европейской территории России может продвинуться дальше на север – в Брянскую, Орловскую, Липецкую, Тамбовскую, Саратовскую, Оренбургскую, южную половину Пензенской, юг Ульяновской, Самарской областей и Башкортостана. Дополнительные проблемы с продвижением вида в северо-восточном направлении на Европейской территории России могут быть обусловлены сопряжённым неблагоприятным воздействием дополнительного фактора – недостаточной влагообеспеченности, поскольку от Саратовской области и восточнее амброзия на северном пределе распространения находится в зоне экологического пессимума одновременно по показателям тепло- и влагообеспеченности.

Проведен эколого-географический анализ встречаемости амброзии полыннолистной (Ambrosia artemisiifolia L.) на северном пределе ее распространения в Канаде. В качестве ведущего фактора, лимитирующего распространение вида на север, выступает недостаточная теплообеспеченность периода созревания семян. С…

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