Distribuição, ecofisiologia e capacidade adaptativa do gênero Montrichardia H. Crueg na Bacia Amazônica

Abstract

In Amazonian floodplains, relatively integral system yet, the vegetation is adapted to regular flooding regime, which determines the distribution of plant species. Besides the effect of water levels, environmental changes, due to the increase in temperature and levels of CO2, may have marked effects on the flora and fauna in these areas. The oscillation of the water level makes these areas so fragile, and the environmental changes are worrying, being necessary to estimate the adaptive capacity and resilience of the system. For this it is essential to find suitable and sensitive biological markers in order to develop and propose conservation strategies. The aim of this study was to provide a set of information about the morphological and physiological adaptive traits of aquatic macrophytes with different amplitudes of distribution, in order to understand how environmental changes affect this group of plants, with fundamental importance to aquatic biota. Morphological, physiological and molecular data of 55 populations of Montrichardia spp. distributed in the Amazon Basin were collected. Data of distribution from herbaria was used to elucidate the ecology of the species at the regional scale (Amazonia) and macro-scale (Neotropical). To estimate the effect of climate change on Montrichardia arborescens an experiment was performed in microcosm with the elevation of temperature and CO2 for five months. The germination and growth of seedling were evaluated. Various environmental parameters and biological characteristics measured demonstrated the clear separation of species M. linifera and M. arborescens. However, genetic analysis did not allow to understand the exact relationship between M. arborescens var. aculeata and the other two other species. The degree of genetic differentiation (RST) between the species M. arborescens and M. linifera, together with the interpretation of the haplotype network, permitted to confirm the separation of these two species, which proved compatible with the morphological separation provided by the analysis of the number of secondary apical veins. The hydrochemical factors proved to influence the distribution of Montrichardia species on a regional scale (Amazonia). While M. linifera occurs mainly in white water rivers, M. arborescens occurs in black water rivers and upland streams. At a macro-scale (Neotropical), precipitation and temperature were the most important factors influencing the species distribution. The simulation of temperature rise and CO2 in microcosms allowed us to infer the effects of climate change on M. arborescens. This species showed a lower accumulation of biomass and lower rate of electron transport when exposed to extremes of temperature and CO2. We conclude that the genus Montrichardia exhibit morphological, physiological and genetic adaptive differences relating to environmental parameters in each of the local environment (várzea and igapó), and that the temperature rise and CO2 influence morphology and physiology of M. arborescens.