3D imaging reveals potential anticipatory responses to increasing intraspecific competition in the Drosophila male reproductive system

July 04, 2021

Juliano Morimoto (1), Renan Barcellos (2), Todd A. Schoborg (3), Liebert Parreiras Nogueira (4), Marcos Vinicius Colaço (5)
bioRxiv, July 2021. DOI: 10.1101/2021.07.22.453343


Bateman gradient; sexual dimorphism; seminal fluid; x-ray microtomography


Selection favour males that anticipate intraspecific competition levels and develop appropriate competitive traits. In holometabolous insects, larval density can act as an ecological cue of males’ future intraspecific competition levels while also limiting access to food allocated to sexually selected traits (e.g., testes). To date, however, most studies have been conducted in larval densities that may have little or no relevance to species’ ecology. Here, we manipulated Drosophila melanogaster larval density based on the natural history of the species and used 3D micro-CT imaging to show a strong modulation of testes volume based on larval density: males from high larval densities generally had larger testes. Conversely, males from high densities tended (albeit not statistically significantly) to have the smallest accessory glands and ejaculatory bulb. Overall, we used micro-CT to measure male reproductive morphology in an ecologically relevant design for which the findings broadly support predictions from sexual selection theory.

How Our Software Was Used

Dragonfly was used for image segmentation.

Author Affiliation

(1) School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Ave Aberdeen AB24 2TZ
(2) COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
(3) Department of Molecular Biology, University of Wyoming, 1000 E. University Ave, Laramie, WY 82071.
(4) Department of Biomaterials, Institute of Clinical Dentistry, University of Oslo. Geitmyrsveien 71, 0455 Oslo, Norway.
(5) Laboratory of Applied Physics to Biomedical Sciences, Physics Institute, State University of Rio de Janeiro, Rio de Janeiro, Brazil.