Too hot for the weeds? Exploring the impact of climate change in herbaceous Convolvulaceae in Cerrado and Mata Atlântica biomes (SE Brazil)

Abstract

Aim: We investigated the potential resilience to climatic change of nine species of weeds in Convolvulaceae, using predictive spatial modeling across two contrasting biomes in Southeastern Brazil: Cerrado (=Savanna) and Mata Atlantica (=Atlantic Forest). We inferred future changes in distribution area, the climatic variables that will be most impactful, and the potential occurrence of future climatic refuges. Location: Southeastern Brazil (Sao Paulo, Brazil). Methods: A total of 195, taxonomically vetted, distribution records were compiled for nine species of Convolvulaceae. Potential distribution areas were modelled in RStudio 1.3.1056 with R 3.6.3 using modleR; environmental layers used were the 19 bioclimatic variables with 30 seconds resolution. After a correlation analysis, four bioclimatic variables were selected for distribution modelling: Temperature Seasonality (BIO4), Mean Temperature of Wettest Quarter (BIO8), Precipitation of Wettest Month (BIO13) and Precipitation of Driest Quarter (BIO17). The species distribution modelling was performed using the Maxent algorithm for the present time (1960-1990) and for future projections (2050 and 2070), under two different scenarios of projections, moderate and pessimistic. The final distribution models were generated through the selection of primary models with a minimum level of TSS (True Skills Statistics) equal to 0.7. Results: The analysed species demonstrated different levels of response to climatic change: Distimake aegyptius, D. dissectus, and Evolvulus pteurocaulon exhibited a gain in the climatic suitability range, regardless of the future scenarios. Other species, such as E. glomeratus, Ipomoea bonariensis, and I. alba showed a decline in climatic suitability range, more accentuated in the pessimistic scenario . Three species showed a positive response in a moderate future scenario, but a decline in the most extreme projection. Areas that may act, in the future, as climatic refuges for the displaced species are also highlighted, in view of being prioritised for conservation.