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AUTOMATED BIOINFORMATICS TO EVALUATE THE RELATIVE CONTRIBUTION OF ENDOSYMBIOSIS AND KLEPTOPLASTY IN THE EVOLUTION OF COMPLEX RED ALGAE
Van Vlierberghe, Mick; Baurain, Denis
2019
 

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Keywords :
Kleptoplaty; Phylogenomics; Bioinformatics; Endosymbiosis; Evolution; Algae
Abstract :
[en] Complex algae form a network of photosynthetic organisms spread across the eukaryotic tree. Among those, CASH lineages have plastids related to red algae, but the mechanisms by which they were acquired remain unclear. Contrary to expectations of secondary endosymbiotic models, a sizable part of their plastid-targeted genes is not from the same origin as the plastid itself. Scenarios as the ancestral cryptic serial endosymbioses or the shopping bag model provide a substantial interpretation of this gene mosaicism but are exclusively focusing on an endosymbiotic mechanism. Similarly, while the Rhodoplex hypothesis fits the single phylogenetic origin of complex red plastids, it does not explain gene mosaicism. Moreover, it implies multiple tertiary (or quaternary) endosymbiotic events, whereas most complex algae do not bear nucleomorphs and only have 3 or 4 membranes surrounding their plastids. To overcome the inconsistencies of those models, we propose kleptoplasty as an additional mechanism for explaining plastid spread in CASH lineages. In line with the shopping bag model, our hypothesis posits multiple transient interactions with preys of diverse origins but also proposes a rationale for the selective force driving the progressive accumulation of plastid-targeted genes: to maintain functional kleptoplastids for increasingly longer periods of time, before ultimately reducing them into fully integrated plastids. In such a scenario, the phylogenetic diversity of plastid-targeted genes would be higher than predicted with endosymbiotic models, where genes originate mostly from a single source, the algal symbiont. To test our hypothesis, we designed and implemented an automated pipeline for building and parsing gene trees in a discovery-driven and taxonomy-aware fashion. This approach allows us to infer whether any given CASH alga rather arose through endosymbiosis or kleptoplasty by reading its position on an alpha-diversity ladder, ranging from (theoretically) single-source nucleomorph-bearing organisms (e.g., Guillardia theta) to multiple-source kleptoplastic organisms (e.g., Dinophysis acuminata).
Research center :
Biological Sciences from Molecules to Systems - inBioS
Disciplines :
Life sciences: Multidisciplinary, general & others
Author, co-author :
Van Vlierberghe, Mick ;  Université de Liège - ULiège > Département des sciences de la vie > Phylogénomique des eucaryotes
Baurain, Denis  ;  Université de Liège - ULiège > Département des sciences de la vie > Phylogénomique des eucaryotes
Language :
English
Title :
AUTOMATED BIOINFORMATICS TO EVALUATE THE RELATIVE CONTRIBUTION OF ENDOSYMBIOSIS AND KLEPTOPLASTY IN THE EVOLUTION OF COMPLEX RED ALGAE
Publication date :
27 August 2019
Event name :
7th European Phycological Congress (EPC7)
Event organizer :
Federation of European Phycological Societies (FEPS)
Event place :
Zagreb, Croatia
Event date :
from 25-08-2019 to 30-08-2019
Audience :
International
Name of the research project :
Phylogénomique des Eucaryotes
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
Available on ORBi :
since 07 September 2019

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