Tue 26 Apr 2016: 3.30pm [QE] – Gowri d/o Rajaratnam on “Deciphering the evolution and development of a novel abdominal appendage in Black Scavenger Flies (Sepsidae: Diptera)”

Department of Biological Sciences, NUS
Qualifying Examination

“Deciphering the evolution and development of a novel abdominal appendage in Black Scavenger Flies (Sepsidae: Diptera)”

Speaker:      Gowri D/O Rajaratnam (Graduate Student, Dept. of Biological Sciences, NUS)
Date:           26 April 2016, Tuesday
Time:           3.30pm
Venue:         Seminar Room 1 (S2 Level 4, #04-14)
Supervisor:  Prof Meier, Rudolf

Abstract: – Despite their diversity in shape and size, most adult insects retain a conserved body plan. Gains of appendages, especially in the proximal abdominal segments, are a rare phenomenon in the insect world. In several sepsid species, however, the males have modified their 4th sternites into appendage-like brushes that are used during courtship.

Here, I propose to study the evolution and development of these remarkable abdominal appendages. Firstly, I reconstructed the evolution of the 4th sternite brushes by carrying out a phylogenetic analysis based on a combination of transcriptomes for 28 species and mitochondrial genomes for 125 species. The results imply that the sternite appendage most likely originated close to the base of the sepsid phylogeny with a subsequent loss and at least one reacquisition. Secondly, in order to understand the ontogeny of this novel appendage, the CRISPR/Cas9 system was optimized for sepsids in order to identify the gene regulatory network that was co-opted during appendage development in different species. Using this system, key candidate genes such as Doublesex and Distal-less will be knocked-out to test their roles in the development of the sternite appendages.

Lastly, I carried out a comparative analysis for 31 sepsid species in order to determine the developmental costs for building abdominal appendages.  I document that males with large and more complex appendages have slower development and emerge smaller than the corresponding conspecific females.

All are welcome

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