Transposable Elements and Trophic Specialization in Blow Flies

• Grant number: 25/26913-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2026
• End date: December 31, 2026
• Field of knowledge: Biological Sciences - Zoology
• Principal Investigator: Tatiana Teixeira Torres
• Grantee: João Gabriel Ignácio da Silva
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 25/12518-1 - Genetic and evolutionary origins of trophic specialization in blowflies: mobile elements and metabolic pathways in a phylogenetic context, AP.R

Abstract

The family Calliphoridae (Diptera: Calyptratae), which includes blow flies, comprises species with distinct larval trophic habits: (1) obligate parasites that feed exclusively on the living tissues of their hosts; (2) necro-saprophagous species that feed on decomposing organic matter; and (3) generalists that exploit both decomposing organic matter and the living tissues of hosts. This diversity makes the group a model system for investigating the genetic determinants underlying the evolution of parasitism. Although previous studies have examined gene expression differences among species with contrasting habits, the role of structural genomic variation, particularly the activity of transposable elements (TEs), remains poorly understood.Transposable elements are mobile DNA sequences capable of directly influencing gene function and regulation, generating new functional elements, or modifying existing regulatory regions. They are classified into retrotransposons (Class I) and DNA transposons (Class II), with additional subclasses such as LINEs, SINEs, and LTR elements. In several organisms, TEs are associated with the emergence of novel phenotypes, such as industrial melanism in Biston betularia, caused by the insertion of a transposon in the cortex gene, and the classic white-eyed mutant in Drosophila melanogaster, resulting from the insertion of the doc transposon in the white gene.With the recent availability of complete and annotated genomes for dozens of calliphorid species, it is now possible to investigate systematically the composition, diversity, and relative abundance of TEs at both macro- and microevolutionary scales. This project aims to perform comparative analyses of TEs in two pairs of species with different trophic habits (macroevolutionary scale), examine their intraspecific distribution using population genomic data from Cochliomyia hominivorax and Cochliomyia macellaria (microevolutionary scale), and test hypotheses regarding the association between TEs and the transition to parasitism.To achieve these goals, the selected student will carry out the following activities:(1) characterize and quantify transposable elements in the genomes of four Calliphoridae species; (2) compare TE repertoires among species with different trophic specializations; (3) assess intraspecific TE diversity in natural populations of C. hominivorax and C. macellaria; and (4) test hypotheses on the association between TEs and trophic adaptations. (AU)