Understanding the mechanisms behind the formation of lichen symbiotic association
| Thesis title in Czech: | Mechanismy vzniku symbiotických asociací lišejníků |
|---|---|
| Thesis title in English: | Understanding the mechanisms behind the formation of lichen symbiotic association |
| Academic year of topic announcement: | 2022/2023 |
| Thesis type: | dissertation |
| Thesis language: | angličtina |
| Department: | Department of Botany (31-120) |
| Supervisor: | doc. Mgr. Pavel Škaloud, Ph.D. |
| Author: | hidden - assigned by the advisor |
| Date of registration: | 06.10.2022 |
| Date of assignment: | 06.10.2022 |
| Preliminary scope of work |
| Background Symbiotic events are shaping the life on Earth since its earliest forms. In fact, symbiosis represents a major driving force in evolution across the entire tree of life, spanning from ancient mitochondrial and plastid endosymbioses to the associations enhancing recent species diversifications. A number of recently published studies greatly enhanced our knowledge on the complexity, evolution and genetic basis of various symbiotic interactions, including lichens, corals, plant-fungal symbioses, marine sponges, and many others. However, considerably less attention is paid to the processes underlying the formation of these symbiotic associations. The lack of a mechanistic understanding of recruitment and community assembly in symbioses prevents, on one hand, to establish conditional links between endosymbiotic and free-living communities in nature, and on the other hand, to decipher the holobiont’s (the host and its symbionts) responses to environmental change and predict its spatio-temporal dynamics. In addition, our recent findings show contrasting diversity patterns between endosymbiotic and free-living algal communities (Vančurová et al, 2020), violating the long-term concept of fungal selection of algal partners from the pool of free-living species. This PhD project aims to uncover the mechanisms behind formation and development of lichen symbiotic associations. Main questions 1) Do the young fungal hosts selectively seek for very rare algal genotypes? 2) What is the deposition rate of airborne symbiotic algae? 3) How does the diversity of endosymbionts change during the lichen development? 4) How do artificial changes of environmental conditions influence the pools of free-living and endosymbiotic algae? 5) Are fungal hosts able to adapt to environmental shifts by switching their endosymbionts? Methodology A total of 2-4 long-term study sites will be established. There, the entire endosymbiotic and free-living community will be characterized by both metabarcoding and Sanger sequencing of isolated algal cells. To answer the questions specified above, a number of experiments will be performed on these plots: ad 1) Pure cultures of fungal hosts will be inoculated on plastic cover slips and these will be mounted on the field. The slides will be observed regularly to investigate the fungal development. Finally, successful symbioses will be molecularly characterized by sequencing. ad 2) A propagule trap will be deployed on the selected locality. The airborne community will be characterized by metabarcoding and compared with the local community. ad 3) Endosymbiotic dynamics will be investigated by metabarcoding of different developmental stages of field-collected lichens. ad 4,5) Artificial exposure to elevated temperatures simulated by open-top chambers and translocation experiments will be performed to simulate changes of major environmental conditions in situ |