Local adaptation and adaptive convergence: the speciation and species coexistence across altitudinal gradients of the Neotropics.

• Grant number: 24/13924-0
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: September 01, 2024
• End date: August 31, 2026
• Field of knowledge: Biological Sciences - Genetics - Plant Genetics
• Principal Investigator: Clarisse Palma da Silva
• Grantee: Drielli Canal
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 21/10639-5 - Center for Research on Biodiversity Dynamics and Climate Change, AP.CEPID

Abstract

The geographical distribution of species is closely related to their physiological tolerances along environmental gradients. Among all abiotic variables, temperature most significantly impacts the performance of organisms along altitudinal gradients, leading to a stratification of species distributions based on their thermal tolerances. Climatic oscillations that cause expansions or contractions in species distributions according to their physiological tolerances can lead to population isolation in refuges. Under climate change, populations scattered across multiple thermal refuges may face limited dispersion, leading to divergence and, eventually, speciation.Species have developed various strategies to cope with stress, from shortening life cycles to maintaining stable metabolism under adverse conditions. Moreover, many species have developed morphophysiological traits that reduce stress severity, preventing deleterious effects on populations. For instance, plants under the same conditions can exhibit different leaf temperatures due to species- and individual-specific traits that deal with thermal stress through radiation, convection, and transpiration.Distinct lineages subject to various conditions tend to show niche divergence due to local adaptations and subsequent speciation. Conversely, unrelated lineages coexisting in similar environments tend to display adaptive convergences. Understanding how different organisms cope with the same stress and how this leads to coexistence in natural communities distributed along altitudinal gradients in the Neotropics is crucial to comprehend how past and present climate changes affect species-rich biomes, such as the Brazilian Atlantic Rainforest.This study aims to investigate the potential effects of an altitudinal gradient of over 2000 meters on phenotypic convergence in communities and on local adaptation and speciation of the Pitcairnia flammea complex, an endemic bromeliad with high morphological variability widely distributed across diverse environments of the Atlantic Rainforest. We will analyze whether populations of P. flammea exhibit different thermal strategies along these altitudinal gradients, defining these strategies through: (I) measurements of photosynthetic thermal sensitivity; (II) survey of morphophysiological traits; and (III) quantification of differential gene expression and identification of positively selected genes. Additionally, we will characterize the thermal sensitivity and morphophysiological patterns of species coexisting with P. flammea along the altitudinal thermal gradient to (IV) test possible patterns of phenotypic convergence or divergence. This will allow us to indicate how species and populations from different altitudes are coping with thermal variations resulting from current climate changes.