Name: Vinicius Ferreira Moreira
Type: PhD thesis
Publication date: 26/10/2022
Advisor:
Name |
Role |
|---|---|
| Paulo Cezar Cavatte | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Elias Terra Werner | Internal Examiner * |
| Leandro Torres de Souza | External Examiner * |
| Mariana Duarte Silva Fonseca | External Alternate * |
| Paulo Cezar Cavatte | Advisor * |
| Sara Dousseau Arantes | Internal Alternate * |
| Tatiana Tavares Carrijo | External Examiner * |
| Viviana Borges Corte | Internal Examiner * |
Summary: Myrsine coriacea is distributed in different phytophysiognomies in the Atlantic Forest and can be found from restinga to high altitude fields. The frequent advances of global warming can modify the structure of the forest community along the altitudinal gradient, interfering with biodiversity and ecosystem
services. Thus, species that remain in an altitudinal gradient will be able to provide information on how to face these climate changes. The general objective of this study is to analyze the morphological responses and the accumulation of reserve compounds in fruits and seeds of populations of M. coriacea (PRIMULACEAE) from different altitudes, as well as to evaluate the potential for photosynthetic acclimatization in seedlings subjected to contrasting thermal conditions. Then, fruit collections were carried out in populations of M. coriacea submitted to an altitudinal variation from 639 to 2160 m in the southeastern region of the country. In the first chapter the polar diameter (PD), the equatorial diameter (ED), the dry mass of the seed (SDM) and the dry mass of the fruit (FDM), showed a decrease in populations of higher altitudes, while the compounds of reserves showed a wide variation in relation to altitude. However, the concentration of lipids (LIP) and phenols (PHE) in seeds and pericarp were more associated with populations at higher altitudes (MAC and CAQ). As a result, the morphological divergence and chemical composition of the fruits and seeds of M. coriacea showed a dependent link with the altitude of origin, but both characteristics were negatively correlated. Even so, the hypothesis that fruits and seeds present smaller size and the increase in the accumulation of reserves in populations
of higher altitudes was accepted. In the second chapter, seven of the ten populations of M. coriacea underwent the germination process and were subsequently subjected to two automatically controlled common garden conditions, one simulating high atmospheric demand [AD] and the other simulating low atmospheric demand [BD]. Six hours before the start of the evaluation, four individuals from high demand were transferred to low demand and vice versa in order to examine the effect of treatments on
plant metabolism and to understand the process of acclimatization of populations from an altitude gradient. Here, 24-hour photosynthetic responses were tested based on the hypothesis that individuals from higher altitudes will have lower photosynthetic performance, low potential for tolerance and less
adaptation to high-demand conditions, while low-altitude populations may indicate a high potential for acclimatization. It was observed that the photosynthetic acclimatization of populations when inserted in
environments different from their origin, revealed a drop in the performance of the population with MAC altitude (1770 m) given by the values of A, E, Fv/Fm, ETR/Ag and Rp /Ag, corroborating the working hypothesis. M. coriacea are able to express characteristics that functionally adjust to the most limiting
sites. However, when subjected to conditions that are highly contrasting to their natural habitat, the adjustment can occur more slowly, causing a reduction in acclimatization and adaptation to new environmental conditions, so populations at higher altitudes can be a threat to climatic advances.
Keywords: Acclimatization; local adaptation; altitudinal gradient; pericarp; seed; temperature.
