Macromorphological variation of the invasive Silverleaf nightshade (Solanum elaeagnifolium Cav.) and its relation to climate and altitude in Morocco

Authors: BEN GHABRIT, SALMANE - Hassan Ii Agricultural And Veterinary Institute; BOUHACHE, MOHAMED - Hassan Ii Agricultural And Veterinary Institute; BIROUK, AHMED - Hassan Ii Agricultural And Veterinary Institute; BON, MARIE-CLAUDE - European Biological Control Laboratory (EBCL)

Submitted to: Review Article
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/6/2019
Publication Date: 7/15/2019
Citation: Ben Ghabrit, S., Bouhache, M., Birouk, A., Bon, M. 2019. Macromorphological variation of the invasive Silverleaf nightshade (Solanum elaeagnifolium Cav.) and its relation to climate and altitude in Morocco. Revue Marocaine des Sciences Agronomiques et Vétérinaires. 7(2), 234-251.

Interpretive Summary: Silverleaf nightshade, Solanum elaeagnifolium, native from the southwestern United States and northern Mexico, is a prominent invasive alien weed in many countries of the Mediterranean Basin including Morocco since its introduction in the mid-20th century. Infestations are creating a serious threat to the Mediterranean basin where water availability is a critical issue for agriculture and people. In the Mediterranean Basin, this is in Morocco where the biology of this ecosystem transformer has been the most studied and where there is a higher risk to spread and establish over a more considerable area. Consequently, studies that identify where are the populations that present a higher risk of becoming invasive are crucial, and this evidence should be used to guide management of emerging and existing invasive species. To start identifying these populations, we first analyzed the variation of 12 macromorphological characters in 709 plants from 218 sites across different ecological conditions in Morocco. The variation clustered in four types of plants, mainly based on their number of shoots and berries. One of the four types which has never been evidenced before corresponds to plants with a higher number of shoots and berries. The type with a low number of shoots and berries is the most invasive ones as it predominates across several ecological conditions including desert climates and high elevation. Our findings do shed light on the identification of potentially more invasive populations and invasiveness indicating characters, which are likely to be importance to land managers.

Technical Abstract: Increased performance of invasive plants in their introduced range vs. their native range has been largely documented. However, performance differences among invasive populations have been less explored, despite this information being central to understanding the evolution of invasiveness as well as being a useful basis to inform management of invasive species. To start examining variation in performance among populations of Silverleaf nightshade (Solanum elaeagnifolium), a prominent invasive weed in many countries in the Mediterranean Basin including Morocco, we measured 12 macromorphological characters in 709 plants from 218 sites across different ecological conditions. Overall, there was significant variation for most characters among populations. The analysis of the structure of this variation by Hierarchical Cluster Analysis and Linear Discriminant Analysis has determined four morphotypes, mostly discriminated by the total number of shoots and of berries. However, the morphotype with lower number of shoots and berries is predominating across Morocco including desert climates and high elevation, and is the most invasive. The geographical distribution of the four morphotypes suggest that Silverleaf nightshade tends to be an r-strategist plant, especially in the most severe ecological conditions. Our findings provide a useful foundation for management of invasive Silverleaf nightshade, and support the recent call for more intra-species research in invasive species biology.