The research team led by the University of Göttingen is looking at the molecular basis of eye size change in insects
The wonderful compound eyes of insects consist of hundreds of individual eyes known as “faces”. In the course of evolution, an enormous variety of sizes and shapes of eyes appeared, often representing adaptations to different environmental conditions. The scientists, led by the Amy Noether research group at the University of Göttingen, along with scientists from the Andalusian Center for Developmental Biology (CABD) in Seville, showed that these differences could be caused by very different changes in the genome of fruit flies. The study has been published in the journal Molecular Biology and Evolution.
Anyone who has seen circles hovering in the air, with a variable speed flash, has likely witnessed a mating attempt where the male chases, with amazing precision, a fast-moving female. To carry out this specialized visual task, flies’ huge compound eyes consist of up to 6,000 individual faces. There are special individual sides pointing towards the sky that show particularly high resolution. In contrast, bark beetles, which spend most of their time hiding in xylem, rarely rely on visual information. Hence, they developed very small eyes with a maximum of 300 sides. “This tremendous diversity is particularly impressive because previous comparative studies have shown that the evolution of insect eyes, as well as ours, is controlled by very similar processes and genes,” says Dr. Nikko Poussinen of the University of Göttingen, who led the study. “It is especially exciting to understand how such a variety in the size and shape of the eyes could arise in the face of very similar genes.” Since many gene-coded proteins work together in regulatory networks to control the development of complex organs, the question arises whether similar differences in eye size are due to changes in similar locations within the networks. As a model for their study, the researchers used several species of the fruit fly genus, some of which we can recognize as the annoying fruit flies that are present in everyone’s kitchen.
The native Drosophila species in Mauritius has up to 250 more faces than closely related species. Although the basic developmental processes are very similar in both of the studied species, numerous differences have been found in their genomes that could explain the observed differences in eye size. A detailed analysis of ocular evolution in both species indicates that changes in an important central node in the gene network lead to the formation of significantly larger eyes in the indigenous species in Mauritius. “Interestingly, in similar work on other Drosophila species, changes are observed in completely different nodes. Therefore, our data show that differences in the number of facets can be caused by very different mechanisms,” sums up the study’s first author, Dr. Elisa Buchberger of University of Göttingen.
“The new data indicate that differences in the number of single eyes in different species of Drosophila arose many times independently in evolution,” says Dr. Mikael Rees. He is the first author of a study published last year by the research group Göttingen. In general, the work of Göttingen’s group contributes to a better understanding of complex organ development. Some of the methods developed in this paper can also be applied to studies in animal and plant breeding, specifically looking for changes in the genome that affect complex traits, such as milk production or fruit size. “In the next step, we want to understand whether different eye sizes have an effect on vision, and see if they are related to the lifestyle of different flies,” Posnien says.
Original publication: Elisa Buchberger et al. Variation in gene expression of the multidirectional axis is associated with interspecific differences in head shape and eye size in Drosophila. Molecular Biology and Evolution (2021). Doi: https: /
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Dr. Niko Bosnin
University of Göttingen
The Johann Friedrich Blumenbach Institute for Zoology and Anthropology
Department of Developmental Biology
Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
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