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Citation
Salazar-Jaramillo, L., Paspati, A., van de Zande, L., Vermeulen, C.J., Schwander, T., Wertheim, B. (2014). Evolution of a cellular immune response in Drosophila: a phenotypic and genomic comparative analysis.  Genome Biol. Evol. 6(2): 273--289.
FlyBase ID
FBrf0224048
Publication Type
Research paper
Abstract

Understanding the genomic basis of evolutionary adaptation requires insight into the molecular basis underlying phenotypic variation. However, even changes in molecular pathways associated with extreme variation, gains and losses of specific phenotypes, remain largely uncharacterized. Here, we investigate the large interspecific differences in the ability to survive infection by parasitoids across 11 Drosophila species and identify genomic changes associated with gains and losses of parasitoid resistance. We show that a cellular immune defense, encapsulation, and the production of a specialized blood cell, lamellocytes, are restricted to a sublineage of Drosophila, but that encapsulation is absent in one species of this sublineage, Drosophila sechellia. Our comparative analyses of hemopoiesis pathway genes and of genes differentially expressed during the encapsulation response revealed that hemopoiesis-associated genes are highly conserved and present in all species independently of their resistance. In contrast, 11 genes that are differentially expressed during the response to parasitoids are novel genes, specific to the Drosophila sublineage capable of lamellocyte-mediated encapsulation. These novel genes, which are predominantly expressed in hemocytes, arose via duplications, whereby five of them also showed signatures of positive selection, as expected if they were recruited for new functions. Three of these novel genes further showed large-scale and presumably loss-of-function sequence changes in D. sechellia, consistent with the loss of resistance in this species. In combination, these convergent lines of evidence suggest that co-option of duplicated genes in existing pathways and subsequent neofunctionalization are likely to have contributed to the evolution of the lamellocyte-mediated encapsulation in Drosophila.

PubMed ID
PubMed Central ID
PMC3942026 (PMC) (EuropePMC)
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    Language of Publication
    English
    Additional Languages of Abstract
    Parent Publication
    Publication Type
    Journal
    Abbreviation
    Genome Biol. Evol.
    Title
    Genome biology and evolution
    ISBN/ISSN
    1759-6653
    Data From Reference