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Wang Z, Pu J, Richards C, Giannetti E, Cong H, Lin Z, Chung H. Evolution of a fatty acyl-CoA elongase underlies desert adaptation in Drosophila. SCIENCE ADVANCES 2023; 9:eadg0328. [PMID: 37647401 PMCID: PMC10468142 DOI: 10.1126/sciadv.adg0328] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 07/31/2023] [Indexed: 09/01/2023]
Abstract
Traits that allow species to survive in extreme environments such as hot-arid deserts have independently evolved in multiple taxa. However, the genetic and evolutionary mechanisms underlying these traits have thus far not been elucidated. Here, we show that Drosophila mojavensis, a desert-adapted fruit fly species, has evolved high desiccation resistance by producing long-chain methyl-branched cuticular hydrocarbons (mbCHCs) that contribute to a cuticular lipid layer reducing water loss. We show that the ability to synthesize these longer mbCHCs is due to evolutionary changes in a fatty acyl-CoA elongase (mElo). mElo knockout in D. mojavensis led to loss of longer mbCHCs and reduction of desiccation resistance at high temperatures but did not affect mortality at either high temperatures or desiccating conditions individually. Phylogenetic analysis showed that mElo is a Drosophila-specific gene, suggesting that while the physiological mechanisms underlying desert adaptation may be similar between species, the genes involved in these mechanisms may be species or lineage specific.
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Affiliation(s)
- Zinan Wang
- Department of Entomology, Michigan State University, East Lansing, MI 48824, USA
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI 48824, USA
| | - Jian Pu
- Department of Entomology, Michigan State University, East Lansing, MI 48824, USA
- College of Agriculture, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Cole Richards
- Department of Entomology, Michigan State University, East Lansing, MI 48824, USA
| | - Elaina Giannetti
- Department of Entomology, Michigan State University, East Lansing, MI 48824, USA
| | - Haosu Cong
- Department of Entomology, Michigan State University, East Lansing, MI 48824, USA
| | - Zhenguo Lin
- Department of Biology, Saint Louis University, St. Louis, MO 63104, USA
| | - Henry Chung
- Department of Entomology, Michigan State University, East Lansing, MI 48824, USA
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI 48824, USA
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Ling L, Mühling B, Jaenichen R, Gompel N. Increased chromatin accessibility promotes the evolution of a transcriptional silencer in Drosophila. SCIENCE ADVANCES 2023; 9:eade6529. [PMID: 36800429 PMCID: PMC9937571 DOI: 10.1126/sciadv.ade6529] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 01/17/2023] [Indexed: 06/18/2023]
Abstract
The loss of discrete morphological traits, the most common evolutionary transition, is typically driven by changes in developmental gene expression. Mutations accumulating in regulatory elements of these genes can disrupt DNA binding sites for transcription factors patterning their spatial expression, or delete entire enhancers. Regulatory elements, however, may be silenced through changes in chromatin accessibility or the emergence of repressive elements. Here, we show that increased chromatin accessibility at the gene yellow, combined with the gain of a repressor site, underlies the loss of a wing spot pigmentation pattern in a Drosophila species. The gain of accessibility of this repressive element is regulated by E93, a transcription factor governing the progress of metamorphosis. This convoluted evolutionary scenario contrasts with the parsimonious mutational paths generally envisioned and often documented for morphological losses. It illustrates how evolutionary changes in chromatin accessibility may directly contribute to morphological diversification.
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Common Themes and Future Challenges in Understanding Gene Regulatory Network Evolution. Cells 2022; 11:cells11030510. [PMID: 35159319 PMCID: PMC8834487 DOI: 10.3390/cells11030510] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/26/2022] [Accepted: 01/29/2022] [Indexed: 12/18/2022] Open
Abstract
A major driving force behind the evolution of species-specific traits and novel structures is alterations in gene regulatory networks (GRNs). Comprehending evolution therefore requires an understanding of the nature of changes in GRN structure and the responsible mechanisms. Here, we review two insect pigmentation GRNs in order to examine common themes in GRN evolution and to reveal some of the challenges associated with investigating changes in GRNs across different evolutionary distances at the molecular level. The pigmentation GRN in Drosophila melanogaster and other drosophilids is a well-defined network for which studies from closely related species illuminate the different ways co-option of regulators can occur. The pigmentation GRN for butterflies of the Heliconius species group is less fully detailed but it is emerging as a useful model for exploring important questions about redundancy and modularity in cis-regulatory systems. Both GRNs serve to highlight the ways in which redeployment of trans-acting factors can lead to GRN rewiring and network co-option. To gain insight into GRN evolution, we discuss the importance of defining GRN architecture at multiple levels both within and between species and of utilizing a range of complementary approaches.
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