Biogeografia e variação morfológica foliar do gênero Passiflora L. (Passifloraceae s.s.) sob variáveis ambientais na Floresta Atlântica, Brasil

Abstract

Passiflora L. is widely distributed in Brazilian biomes, particularly in the southeast of the Atlantic Forest where it is recorded with expressive richness. Although the genus stands out for the great leaf morphological plasticity (possibly related to abiotic factors), there are few studies about it. This study was all performed within the Atlantic domain. The biogeographic study of the Passiflora genus was carried in the region of Serra da Mantiqueira (SM) to investigate its distribution in an environmental gradient based on field data and botanic collections (online and herbaria). We employed a spatial analysis of richness, sampling effort, and similarity by area and altitude/physiognomy out using georeferencing software and the R program, from 2.5º × 2.5º grids. We evaluated species richness/occurrence by altitude through a test of significance and species conservation status in the area by overlaying the richness with the shapefile of studied Conservation Unit (UC). We also investigated the influence of environmental variables on the leaf morphology of five Passiflora species (P. amethystina, P. campanulata, P. capsularis, P. mediterranea and P. porophylla) on the regional scale (UC: Caparaó National Park - PNC, Itatiaia National Park - PNI, Serra dos Órgãos National Park - PARNASO, Serra do Brigadeiro State Park – PESB, and Ibitipoca State Park - PEIB), and macro-scale (Atlantic domain). The morphometric analysis showed that the leaf characters were related to abiotic factors (climate, soil, altitude, and light) obtained for each specimen on the field. We used a Non-Metric Multidimensional Scaling (NMDS) analysis with the index Gower to evaluate the relationship of environmental variables with general leaf morphology, and Linear Mixed Models (GLMM) to evaluate the relationship of environmental variables with individual leaf characters. In the biogeography study, we obtained 50 species recorded for the SM and concluded that the composition of Passiflora changes along the altitude gradient, and reaches greater richness at 1000 m of elevation in the montane type phytophysiognomies. The species composition is different between the two portions of the SM: north and south. Our results on leaf variation indicated significant relationships between climatic and edaphic factors with the general morphology, individual characters of size, defense characteristics (extrafloral nectaries and variegations), and shape of leaves. The species P. campanulata, P. amethystina and P. porophylla showed greater response to environmental variables differing by population. Due to the great differentiation found in the leaves and reproductive characters of P. campanulata, we suggest the description of a new species of P. section Dysosmia collected in the PNC, in the northern portion of the SM. Our results amplified the knowledge about the biology, ecology and taxonomy of Passiflora species, distribution patterns, and conservation of the genus in SM. Above all, we bring a new perspective on the leaf plasticity of Passiflora discussing the influence of climatic and edaphic gradients on this.