Spotifly · Genetic paths underlying the convergent evolution of pigmented spots on fly wings
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2016-05-01 → 2018-04-30
- EU contribution
- €159,461
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
Genetic paths underlying the convergent evolution of pigmented spots on fly wings
In all animals, genes are only expressed (~active) in a subset of cells and each cell type is determined by a specific combination of expressed genes. The expression of genes is thus regulated, and this regulation depends on sequences controlling “where” and “when” genes are expressed, the ‘enhancers’. Enhancers, when bound by specific transcription factors, stimulate the expression of their target gene. Transcription factor binding depends on specific sequence motifs. The mere introducing of these motifs in any sequence, however, doesn’t result in a functional enhancer. There must be rules, still unclear, that govern the functionality of enhancers. Understanding these rules is critical, as all biological processes depend on the correct expression of specific genes in space and time. Deciphering these rules might be made easier by comparing enhancers with a similar function that have evolved independently. This comparison would reveal what is constrained and what is flexible in the organization of an enhancer. In collaboration with Benjamin Prud’homme’s lab in Marseille, we studied 3 independently evolved enhancers active in the anterior part of the wing in 3 fruit fly species. While hundreds of transcription factors are present in this tissue, we found three that regulate at least 2 of these enhancers, suggesting strong biases in the evolutionary recruitment of these factors. We also found that these 3 enhancers evolved in the vicinity of (different) pre-existing enhancers, suggesting that the evolutionary path to a novel enhancer may be shortened by the re-use of some of the features of an “older” enhancer.
Data: CORDIS, © European Union
Project objective
When a phenotype evolves twice in independent lineages, are the underlying molecular mechanisms similar? In the case of similar pigmentation patterns that have arisen independently in two fruit fly species, Drosophila tristis and Drosophila biarmipes, the question, becomes: is there a unique genetic path to gain a pigmentation spot on the wing? Each pigmentation pattern is prefigured by the developmental expression of yellow, a gene necessary for the production of black pigments. In each case, yellow expression results from a novel enhancer, both enhancers sharing no homology. To understand how these new regulatory activities have independently emerged, we will first perform an RNAi screen to identify transcription factors controlling each enhancer. We will then characterize the candidate transcription factors identified, assess their genetic sufficiency and the directness of the regulatory link. We will evaluate the degree of convergence in the control of the activity of the two enhancers by closely comparing the relationship between their structure and their function. We will compare sequences between species that carry the regulatory activity and species that do not. We will identify in which context binding sites that convey the activity evolved (position, spacing, orientation). Moreover, we will distinguish among sites contributing permissive or instructive (spatio-temporal) input. This project tackles the open question of how a new regulatory activity emerges. The contribution of each input is key element to enhancer activity, and is hardly understood in any system. The model we use may represent a rare case where the evolution of a regulatory activity can be deciphered functionally.Our work will also address the question of the repeated evolution of complex traits, often associated to regulatory changes. We will assess the level of functional constraint that may channel the emergence of the same regulatory activity to the same molecular mechanisms.
Original text from CORDIS.
Participants
- LUDWIG-MAXIMILIANS-UNIVERSITAET MUENCHEN · PlaneggCoordinatorGermany
Links
- View on CORDIS
- DOI: 10.3030/701691
- http://www.evolutionary-ecology.bio.lmu.de/evolution_development/index.html
Data: CORDIS, © European Union