Drivers of bromeliad leaf and floral bract variation across a latitudinal gradient in the Atlantic Forest

Abstract

Aim: Understanding the complex interaction and relative contributions of factors involved in species and trait diversification is crucial to gain insights into the evolution of Neotropical biodiversity. Here, we investigated the drivers of morphological variation in bromeliads along a latitudinal gradient in a biodiversity hotspot. Location: Atlantic Forest, Brazil.Taxon: A species complex in the genus Vriesea (Bromeliaceae). Methods:We measured shape and size variation for 208 floral bracts and 176 leaves in individuals from 14 localities using geometric morphometrics. We compiled data for two chloroplast regions (matK and trnL-F) from 89 individuals to assess genetic diversity, population structure and phylogenetic relationships. We tested the influence of climate, altitude and genetic distance on morphological traits using linear statistical models.Results: Temperature seasonality is a main driver of floral bract shape. Together with precipitation, it also explains changes in leaf size across the latitudinal gradient. Shifts in morphological traits are correlated with genetic structure and partly support the recent taxonomic delimitation proposed for the species complex. The species started to diversify in the Pliocene ca. 5 Mya. We detected a phylogeographical break in species distribution into northern and southern clades between the Bocaina region and the southern portion of the Atlantic Forest. Main Conclusions:We identify how geography and environmental changes through time shape floral bracts and leaves in similar ways. At highly seasonal sites with lower annual precipitation (in the southern subtropical portion of the Atlantic Forest), leaves are larger and floral bracts are wide-elliptic, making them better suited for increased water accumulation. In contrast, at less seasonal sites (in the tropical north, where rainfall is more abundant and temperatures are higher), leaves are narrower and floral bracts are lanceolate-shaped, facilitating water drainage. The biogeographical break we identified suggests a role of tectonic activity and climatic oscillations in promoting species divergence and diversification.

Vascular epiphytism on the Sinos River riparian forest: phytosociological and conservation analysis

“…The occurrence of tank bromeliads largely restricted to environments with better conservation, in late stages of epiphytic succession (Bonnet et al, 2011) and, consequently, with better environmental quality. Additionally, other studies have reported the prevalent occurrence of these plants in Dense Humid Forest, also linking it to areas with higher rainfall (Neves et al, 2020). Unlike the present study, in Caraá, Barbosa et al (2015) have reported Microgramma squamulosa and Pleopeltis pleopeltifolia as the two most important species, thus reinforcing the secondary feature of this other forest fragment.…”

Lake-depth related pattern of genetic and morphological diatom diversity in boreal Lake Bolshoe Toko, Eastern Siberia

“…In general, genetic and morphological investigations of diatoms from water or sediment samples show a good overlap between the overall taxa composition, although genetic studies show stronger differences in the relative abundance of sequence reads per sample and indicate higher diversity as well as assigning taxa to a higher taxonomic level depending on the completeness of the reference database [22,24,27]. Besides retrieving taxonomic community compositions by metabarcoding, phylogenetically informative genetic markers also provide an estimation of the phylogenetic diversity [28], which is limited in short barcodes but can be sufficient to display phylogenetic patterns within genera [29]. In general, phylogenetic diversity analyses allow the assessment of whether communities are phylogenetically clustered, which is mostly caused by environmental filtering or if they are phylogenetically over dispersed, which can be a result of biotic interactions [30,31].…”

Pollinators drive floral evolution in an Atlantic Forest genus

“…amplitude of the Atlantic Forest also make it a prime study area for plant diversification ( Antonelli and Sanmartín 2011 ; Alvares et al 2013 ). Such extraordinary environmental heterogeneity has been shown to influence Vriesea species diversification and variation in morphological traits ( Neves et al 2019 ).…”