PUBLICATION
Genetic and developmental origins of a unique foraging adaptation in a Lake Malawi cichlid genus
- Authors
- Conith, M.R., Hu, Y., Conith, A.J., Maginnis, M.A., Webb, J.F., Albertson, R.C.
- ID
- ZDB-PUB-180622-20
- Date
- 2018
- Source
- Proceedings of the National Academy of Sciences of the United States of America 115(27): 7063-7068 (Journal)
- Registered Authors
- Albertson, R. Craig, Webb, Jacqueline
- Keywords
- TGFβ, craniofacial, evo-devo, ligament, novelty
- MeSH Terms
-
- ADAM12 Protein/genetics*
- Adaptation, Physiological*
- Animals
- Basic Helix-Loop-Helix Transcription Factors/genetics*
- Cichlids/genetics*
- Fish Proteins/genetics*
- Lakes
- Malawi
- Transforming Growth Factor beta/genetics*
- PubMed
- 29915062 Full text @ Proc. Natl. Acad. Sci. USA
Citation
Conith, M.R., Hu, Y., Conith, A.J., Maginnis, M.A., Webb, J.F., Albertson, R.C. (2018) Genetic and developmental origins of a unique foraging adaptation in a Lake Malawi cichlid genus. Proceedings of the National Academy of Sciences of the United States of America. 115(27):7063-7068.
Abstract
Phenotypic novelties are an important but poorly understood category of morphological diversity. They can provide insights into the origins of phenotypic variation, but we know relatively little about their genetic origins. Cichlid fishes display remarkable diversity in craniofacial anatomy, including several novelties. One aspect of this variation is a conspicuous, exaggerated snout that has evolved in a single Malawi cichlid lineage and is associated with foraging specialization and increased ecological success. We examined the developmental and genetic origins for this phenotype and found that the snout is composed of two hypertrophied tissues: the intermaxillary ligament (IML), which connects the right and left sides of the upper jaw, and the overlying loose connective tissue. The IML is present in all cichlids, but in its exaggerated form it interdigitates with the more superficial connective tissue and anchors to the epithelium, forming a unique ligament-epithelial complex. We examined the Transforming growth factor β (Tgfβ) → Scleraxis (Scx) candidate pathway and confirmed a role for these factors in snout development. We demonstrate further that experimental up-regulation of Tgfβ is sufficient to produce an expansion of scx expression and concomitant changes in snout morphology. Genetic and genomic mapping show that core members of canonical Tgfβ signaling segregate with quantitative trait loci (QTL) for snout variation. These data also implicate a candidate for ligament development, adam12, which we confirm using the zebrafish model. Collectively, these data provide insights into ligament morphogenesis, as well as how an ecologically relevant novelty can arise at the molecular level.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping