Efeitos da relação filogenética e da similaridade funcional na invasibilidade de plantas na Caatinga

Abstract

One of the main questions in biological invasions studies is the reason why numerous species are introduced, but only some become invasive. This shift in status has been justified by the phylogenetic relationship and functional similarity between exotic and native species. However, these patterns have not been explored in semi-arid environments like the Caatinga. Thus, the aim of this work is to test how phylogenetic and functional similarity between exotic and native plants in the Caatinga affect invasion status and distribution of invasive species. To achieve this, we constructed a list of exotic plants and obtained their respective invasion statuses in the Caatinga. We gathered occurrence data for these species and native plants. Additionally, a functional database was constructed for these species, including Leaf Area (LA), Height (H), and Seed Mass (SM) attributes. Using the occurrences, we created diversity fields for exotic species, representing the composition of native species that co-occur with each exotic species and calculated phylogenetic metrics for the focal species' distance to its field. Binomial GLMs were employed to assess whether changes in status from exotic to naturalized and from naturalized to invasive are influenced by phylogenetic relationships and functional attributes. For invasive species, we tested if observed phylogenetic distance values differ from those expected by chance. Lastly, we analyzed if there are functional similarities between the statuses of exotic species and native plants. We found that plants phylogenetically closer to Caatinga natives are more likely to become naturalized and invasive. Smaller plants also have a higher probability of becoming naturalized. Among invasive species with a phylogenetic relationship different from what is expected by chance, there is a prevalence of species phylogenetically closer to natives in their field. In comparing statuses, naturalized and invasive plants were found to be shorter and have smaller leaves and seeds than native plants in the Caatinga. The results indicate that Caatinga's environmental filter appears to favor species more similar to natives. The observed functional differences suggest that naturalized and invasive species are competitive, adopting strategies similar to native plants of Caatinga, such as seed bank formation and dense populations during a specific period of the year.