Wed, 17 Apr 2013,10am @ S1A SR: Mindy Tuan on “Comparative and experimental approaches to understanding sexual selection of sepsid flies”

Qualifying  Examination

“Comparative and experiment approaches to understanding  sexual selection of sepsid flies”


Speaker: Mindy Tuan 
Graduate Student,
Dept. of Biological Sciences, NUS
Wednesday, 17th April 2013: 10.00am
At the S1A Seminar Room, S1A- 02-17
(Next to the S1A Car Park/CBIS)
Supervisor: Prof Rudolf Meier

All are welcome


“Males often differ from females by having exaggerated ornaments and/or performing complex behaviours. Such sexually dimorphic traits are usually the product of sexual selection and can be morphological, behavioural, chemical or tactile in nature.

Here I use sepsid flies to study the evolution of such sexual dimorphisms to test whether they evolve faster and make a more significant contribution to speciation when compared with non-sexual traits.

Sepsid flies occur worldwide and comprise over 300 species. They possess a fascinating array of sexually dimorphic morphological and behavioural traits that are used during mating. In my research, I use sepsid flies to quantify the amount of correlated evolution between morphology and behaviour, study the evolution of copulation duration, and compare character change in pairs of closely related species and distantly related, allopatric populations.

My comparative work on 30 species already shows that sepsid fly mating behaviour varies tremendously, with flies assuming static positions and performing dynamic actions that are largely sex-specific. Furthermore, my data clarifies the relationship between morphology and behaviour by indicating instances in which morphological change is linked to behavioural change, and instances in which there is no such correlation.

I also studied the evolution of copulation duration across the 29 taxa and demonstrate that it evolves quickly although there is a significant phylogenetic effect with “basal” species having longer copulation times. I am currently testing whether this pattern correlates with the complexity of behaviour and morphology.

Moreover, I will look for traits that are influential in speciation, by studying morphological, behavioural and chemical traits in groups of closely related sister species (genetic distance for COI: 0-3%), as well as distantly related populations of a species (genetic distance for COI: 1.5% to 3%). Preliminary data suggest that behavior and morphology may evolve the fastest while the chemicals in a sexually dimorphic male gland evolve slowly.”


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