Banca de QUALIFICAÇÃO: INGRID ELAINE RODRIGUES DOMINGOS

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : INGRID ELAINE RODRIGUES DOMINGOS
DATE: 15/09/2023
TIME: 14:00
LOCAL: Didático 1-DECOL/CB
TITLE:

EVOLUTION OF SALINITY TOLERANCE IN FRESHWATER CYANOBACTERIA

KEY WORDS:

Salinization;Microcystis;Adaptation;Growth;Cell size;Toxins;

PAGES: 50
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUMMARY:

Salinization of freshwater due to shifting climate, urbanization, and use of salts for fertilizers and deicing, is an ongoing but relatively poorly studied global change. As a physiological stressor in freshwater systems, salinization is a threat to biodiversity, key ecosystem functions and services, and likely exerts evolutionary selective pressure on species. Yet, how species locally adapt to salinization via microevolutionary processes is barely understood. Accordingly, we investigated the capacity of genotypic adaptation of the globally prevalent bloom forming cyanobacteria Microcystis to increased salinity, and the subsequent changes in morphology, physiology and toxin quota. For this, we set up a common garden experiment with  four strains of toxin-producing Microcystis.  Prior to the common garden, all strains were split in triplicate populations, each exposed to  0 (no salinity stress, therefore “non-adapted” populations) and 1.5 g/L of NaCl (i.e., “adapted” populations) for > 100 generations. After this period, each population (adapted and non adapted) was exposed to treatments of 0, 1.5, 3 and 5 g/L of NaCl in a common garden design for another 8 generations to remove maternal effects, after which growth and traits were measured. Adapted populations of all strains showed higher growth rates compared to non-adapted ones and grew in all treatments, indicating genotypic evolution of salt tolerance driven by selection on existing genetic variation in a period of 5 months. Adaptation also resulted in smaller sized cells for all strains. Two out of four strains produced colonies at higher salinities. Colony formation and size was higher in non-adapted populations, indicating that adapted populations did not benefit from investing in colony formation. Toxin (microcystin) and total phosphorus analyses are  ongoing. The results demonstrate that adaptation to relatively low concentrations (1.5 g /L) also enables tolerance to higher  salinities (>3 g/L). We show, for the first time, rapid evolutionary adaptation of a common aquatic primary producer to freshwater salinization over ecological time, with effects on key traits such as body size. It is likely that such adaptation occurs commonly in nature, though its consequences on the ecosystem functions and services is unknown. Our results justify a broader look into the eco-evolutionary implications of salinization driven selection in aquatic ecosystems.

COMMITTEE MEMBERS:
Presidente - 1103317 - KEMAL ALI GER
Interno - 1678202 - CARLOS ROBERTO SORENSEN DUTRA DA FONSECA
Interna - 1764855 - VANESSA BECKER