Evolution of larval segment position across 12 Drosophila species* |
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Authors: | Gizem Kalay Joel Atallah Noemie C. Sierra Austin M. Tang Amanda E. Crofton Mohan K. Murugesan Sherri Wykoff-Clary Susan E. Lott |
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Affiliation: | 1. Department of Evolution and Ecology, University of California, Davis, One Shields Avenue, Davis, California, 95616;2. Earth and Planetary Sciences Department, University of California, Davis, One Shields Avenue, Davis, California, 95616 |
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Abstract: | Many developmental traits that are critical to the survival of the organism are also robust. These robust traits are resistant to phenotypic change in the face of variation. This presents a challenge to evolution. In this article, we asked whether and how a well-established robust trait, Drosophila segment patterning, changed over the evolutionary history of the genus. We compared segment position scaled to body length at the first-instar larval stage among 12 Drosophila species. We found that relative segment position has changed many times across the phylogeny. Changes were frequent, but primarily small in magnitude. Phylogenetic analysis demonstrated that rates of change in segment position are variable along the Drosophila phylogenetic tree, and that these changes can occur in short evolutionary timescales. Correlation between position shifts of segments decreased as the distance between two segments increased, suggesting local control of segment position. The posterior-most abdominal segment showed the highest magnitude of change on average, had the highest rate of evolution between species, and appeared to be evolving more independently as compared to the rest of the segments. This segment was exceptionally elongated in the cactophilic species in our dataset, raising questions as to whether this change may be adaptive. |
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Keywords: | Drosophila evolution larval stage robustness segment patterning |
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