Phylogeny explains why less therapeutically redundant plant species are not necessarily facing greater use pressure

Plant parentage influences the type of timber use by traditional peoples of the Brazilian Caatinga

Local populations select different plants to meet their demands, so that morphologically similar species can be more used for a given use. Herein, we seek to understand whether plant species that are phylogenetically closer together are used more similarly than distant species in the phylogeny. Ethnobotanical data were collected in five rural communities in a semi-arid region of Brazil. A total of 120 local experts were selected and interviewed using semi-structured questionnaires. The people's knowledge of plants was organized into usage subcategories. We estimated the redundancy values for the mentioned species, and we compiled data from the literature on the wood density values of the cited species. We constructed our phylogenetic hypothesis of useful plants and used comparative phylogenetic methods to estimate the signal. Our results showed a strong phylogenetic grouping for both tool handle and craft uses. We observed a moderate phylogenetic grouping in which related cited plants exhibit similar redundancy and a weak grouping in which cited plants present similar wood density values. Our results revealed the importance of using phylogeny for useful plants. We conclude the phylogenetic proximity of useful plants and the lower redundancy for some species in our study may suggest greater use pressure, given that few species fulfill the same function.

Wild food plants of Brazil: a theoretical approach to non-random selection

Ethnobiological investigations have focused on identifying factors that interfere with the criteria adopted for selection of plants, especially medicinal plants, by different populations, confirming the theory that plant selection is not random. However, regarding wild food plants, little effort has been made to confirm the theory in this context, especially in Brazil. Therefore, this systematic review aimed to contribute to the establishment of theoretical bases of the non-random selection of wild food plants by local populations in Brazil. For this, searches were made in 4 databases, namely, Web of Science, Scielo, Scopus and PubMed, using 8 sets of keywords in English and Portuguese in order to identify wild food plants occurring in Brazil. The steps were: application of inclusion and exclusion criteria, screening of articles, selection of studies based on risk of bias, data treatment and, finally, data analysis. Eighty articles met the inclusion criteria of this review. However, 45 of them were considered to present high risk of bias and thus 35 articles were kept for the identification of overused and underused families. The results were inferred through two different approaches (IDM and Bayesian). Annonaceae, Arecaceae, Basellaceae, Cactaceae, Capparaceae, Caryocaraceae, Myrtaceae, Passifloraceae, Rhamnaceae, Rosaceae, Sapotaceae, Talinaceae, and Typhaceae were considered overused. Eriocaulaceae, Orchidaceae, and Poaceae were considered underused. Therefore, considering that some families are more (or less) used than others, we confirm that the wild food plants occurring in Brazil, known and used by different populations, are not chosen at random.

Alien woody plants are more versatile than native, but both share similar therapeutic redundancy in South Africa

Understanding why alien plant species are incorporated into the medicinal flora in several local communities is central to invasion biology and ethnobiology. Theories suggest that alien plants are incorporated in local pharmacopoeias because they are more versatile or contribute unique secondary chemistry which make them less therapeutically redundant, or simply because they are locally more abundant than native species. However, a lack of a comprehensive test of these hypotheses limits our understanding of the dynamics of plants knowledge, use and potential implications for invasion. Here, we tested the predictions of several of these hypotheses using a unique dataset on the woody medicinal flora of southern Africa. We found that the size of a plant family predicts the number of medicinal plants in that family, a support for the non-random hypothesis of medicinal plant selection. However, we found no support for the diversification hypothesis: i) both alien and native plants were used in the treatment of similar diseases; ii) significantly more native species than alien contribute to disease treatments particularly of parasitic infections and obstetric-gynecological diseases, and iii) alien and native species share similar therapeutic redundancy. However, we found support for the versatility hypothesis, i.e., alien plants were more versatile than natives. These findings imply that, although alien plant species are not therapeutically unique, they do provide more uses than native plants (versatility), thus suggesting that they may not have been introduced primarily for therapeutic reasons. We call for similar studies to be carried out on alien herbaceous plants for a broader understanding of the integration of alien plants into the pharmacopoeias of the receiving communities.