Banca de DEFESA: INGRID ELAINE RODRIGUES DOMINGOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : INGRID ELAINE RODRIGUES DOMINGOS
DATE: 28/02/2024
TIME: 13:30
LOCAL: Google meet
TITLE:

Salinization causes rapid evolution of tolerance and smaller cell size in a common bloom forming cyanobacteria

KEY WORDS:

Salinization; Microcystis; Adaptation; Growth ; Cell size;

PAGES: 36
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUMMARY:

Global changes act as selective forces responsible for inducing the genotypic adaptation (evolution)  in species over a short period, with little or no information about subsequent ecological effects. As a stress factor in freshwater ecosystems, salinization not only poses a threat to biodiversity and the primary functions and services of ecosystems but also imposes selective pressure on species. However, the way species adapt locally to salinization through microevolutionary processes is poorly understood. Therefore, we investigated the genotypic adaptation capacity of the cyanobacterium Microcystis aeruginosa, a major contributor to global blooms, to increased salinity and the resulting changes in growth and morphology. For this purpose, we conducted a Common Garden experiment with four toxin-producing strains of Microcystis. Before the Common Garden experiment, all strains were divided into three populations (replicas) and exposed to two treatments: the addition of  NaCl (1.5 g/L) and the control (0 g/L of NaCl) for over 100 generations (6-8 months). After this period, each population was exposed to treatments of 0, 1.5, 3, and 5 g/L of NaCl with 3 replicas each in a Common Garden project for an additional 7 generations in order to remove the effects of phenotypic and epigenetic adaptation. After this stage, growth and morphological characteristics were measured. To test how salinity concentrations and fitness factors affect Microcystis growth and morphology, we used Generalized Linear Models. Populations exposed to a concentration of 1.5 g/L during the selection stage (adapted) showed higher growth rates compared to those exposed to the control (non-adapted) and grew in all salinization treatments, indicating an increased salt tolerance driven by selection in genetic variation. Selection also resulted in smaller cell sizes for all strains. Two strains originally grown as individual cells produced colonies in higher salinities. The formation of colonies and colony size increased in non-adapted populations, indicating that adapted populations probably do not need to invest in colony formation in order to survive. The results demonstrate that adaptation to relatively low concentrations (1.5 g/L) of salt also allows tolerance to higher salinities (>3 g/L). We have shown, for the first time, the rapid evolutionary adaptation of a common aquatic primary producer to freshwater salinization over ecological time, with effects on key traits such as  cell size. Such adaptation is likely to occur in other cyanobacteria and phytoplankton species in nature where salinization occurs, with consequences for ecosystem functions and services that are still unknown. Our results justify a broader view of the eco-evolutionary implications of salinization-driven selection in aquatic ecosystems.

COMMITTEE MEMBERS:
Presidente - 1103317 - KEMAL ALI GER
Externa à Instituição - SANDRA MARIA FELICIANO DE OLIVEIRA E AZEVEDO
Interna - 1764855 - VANESSA BECKER