scholarly journals The cichlid oral and pharyngeal jaws are evolutionarily and genetically coupled

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Andrew J. Conith ◽  
R. Craig Albertson
Keyword(s):  
Prey Capture ◽  
Phenotypic Change ◽  
Functional Constraints ◽  
East African ◽  
Genetic Level ◽  
Evolutionary Success ◽  
African Rift ◽  
Pharyngeal Jaws ◽  
African Cichlids ◽  
Pharyngeal Jaw

AbstractEvolutionary constraints may significantly bias phenotypic change, while “breaking” from such constraints can lead to expanded ecological opportunity. Ray-finned fishes have broken functional constraints by developing two jaws (oral-pharyngeal), decoupling prey capture (oral jaw) from processing (pharyngeal jaw). It is hypothesized that the oral and pharyngeal jaws represent independent evolutionary modules and this facilitated diversification in feeding architectures. Here we test this hypothesis in African cichlids. Contrary to our expectation, we find integration between jaws at multiple evolutionary levels. Next, we document integration at the genetic level, and identify a candidate gene, smad7, within a pleiotropic locus for oral and pharyngeal jaw shape that exhibits correlated expression between the two tissues. Collectively, our data show that African cichlid evolutionary success has occurred within the context of a coupled jaw system, an attribute that may be driving adaptive evolution in this iconic group by facilitating rapid shifts between foraging habitats, providing an advantage in a stochastic environment such as the East African Rift-Valley.

scholarly journals Modularity of the Oral Jaws Is Linked to Repeated Changes in the Craniofacial Shape of African Cichlids

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Kevin J. Parsons ◽  
W. James Cooper ◽  
R. Craig Albertson
Keyword(s):  
Character Displacement ◽  
East African ◽  
Model Selection Approach ◽  
Selection Approach ◽  
Primary Axis ◽  
African Rift ◽  
Pharyngeal Jaws ◽  
African Cichlids ◽  
Variational Modularity

The African cichlids of the East-African rift-lakes provide one of the most dramatic examples of adaptive radiation known. It has long been thought that functional decoupling of the oral and pharyngeal jaws in cichlids has facilitated their explosive evolution. Recent research has also shown that craniofacial evolution from radiations in lakes Victoria, Malawi, and Tanganyika has occurred along a shared primary axis of shape divergence, whereby the preorbital region of the skull changes in a manner that is, relatively independent from other head regions. We predicted that the preorbital region would comprise a variational module and used an extensive dataset from each lake that allowed us to test this prediction using a model selection approach. Our findings supported the presence of a preorbital module across all lakes, within each lake, and for Malawi, within sand and rock-dwelling clades. However, while a preorbital module was consistently present, notable differences were also observed among groups. Of particular interest, a negative association between patterns of variational modularity was observed between the sand and rock-dwelling clades, a patter consistent with character displacement. These findings provide the basis for further experimental research involving the determination of the developmental and genetic bases of these patterns of modularity.

TECTONOMAGMATIC EVOLUTION OF THE EAST AFRICAN RIFT SYSTEM AS DOCUMENTED IN WEST TURKANA, KENYA

2017 ◽  
Author(s):  
Sara Mana ◽  
◽  
Merry Yue Cai ◽  
Catherine C. Beck ◽  
Steven L. Goldstein
Keyword(s):  
East African Rift ◽  
Rift System ◽  
East African Rift System ◽  
East African ◽  
African Rift

FEEDBACK BETWEEN STRUCTURAL INHERITANCE, MAGMA-PLUMBING AND FAULTING IN A MULTIPHASE RIFT: THE SHIRE GRABEN, EAST AFRICAN RIFT

2019 ◽  
Author(s):  
Travis J. Vick ◽  
◽  
Folarin Kolawole ◽  
Estella A. Atekwana ◽  
Daniel Lao-Davila ◽  
...  
Keyword(s):  
East African Rift ◽  
East African ◽  
Structural Inheritance ◽  
African Rift ◽  
Magma Plumbing

PLIO-PLEISTOCENE PALEOENVIRONMENTS IN WEST TURKANA (EAST AFRICAN RIFT SYSTEM, KENYA)

2020 ◽  
Author(s):  
Alexis Nutz ◽  
◽  
Mathieu Schuster ◽  
Doris Barboni ◽  
Ghislain Gassier ◽  
...  
Keyword(s):  
East African Rift ◽  
Rift System ◽  
East African Rift System ◽  
East African ◽  
African Rift

Hypoxia Tolerance in Twelve Species of East African Cichlids: Potential for Low Oxygen Refugia in Lake Victoria

1995 ◽  
Vol 9 (5) ◽  
pp. 1274-1288 ◽  
Author(s):  
LAUREN J. CHAPMAN ◽  
LESLIE S. KAUFMAN ◽  
COLIN A. CHAPMAN ◽  
F. ELLIS MCKENZIE
Keyword(s):  
Lake Victoria ◽  
Hypoxia Tolerance ◽  
Low Oxygen ◽  
East African ◽  
East African Cichlids ◽  
African Cichlids

scholarly journals Evolution of regulatory networks associated with traits under selection in cichlids

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Tarang K. Mehta ◽  
Christopher Koch ◽  
Will Nash ◽  
Sara A. Knaack ◽  
Padhmanand Sudhakar ◽  
...  
Keyword(s):  
Visual System ◽  
Regulatory Sequence ◽  
Potential Candidate ◽  
East African ◽  
Regulatory Regions ◽  
A Genome ◽  
Opsin Genes ◽  
East African Cichlids ◽  
Gene Regulatory ◽  
African Cichlids

Abstract Background Seminal studies of vertebrate protein evolution speculated that gene regulatory changes can drive anatomical innovations. However, very little is known about gene regulatory network (GRN) evolution associated with phenotypic effect across ecologically diverse species. Here we use a novel approach for comparative GRN analysis in vertebrate species to study GRN evolution in representative species of the most striking examples of adaptive radiations, the East African cichlids. We previously demonstrated how the explosive phenotypic diversification of East African cichlids can be attributed to diverse molecular mechanisms, including accelerated regulatory sequence evolution and gene expression divergence. Results To investigate these mechanisms across species at a genome-wide scale, we develop a novel computational pipeline that predicts regulators for co-extant and ancestral co-expression modules along a phylogeny, and candidate regulatory regions associated with traits under selection in cichlids. As a case study, we apply our approach to a well-studied adaptive trait—the visual system—for which we report striking cases of network rewiring for visual opsin genes, identify discrete regulatory variants, and investigate their association with cichlid visual system evolution. In regulatory regions of visual opsin genes, in vitro assays confirm that transcription factor binding site mutations disrupt regulatory edges across species and segregate according to lake species phylogeny and ecology, suggesting GRN rewiring in radiating cichlids. Conclusions Our approach reveals numerous novel potential candidate regulators and regulatory regions across cichlid genomes, including some novel and some previously reported associations to known adaptive evolutionary traits.

scholarly journals The geological history of the Lake Rudolf Basin, Kenya colony

1939 ◽  
Vol 229 (560) ◽  
pp. 219-274 ◽  
Keyword(s):  
Rift Valley ◽  
Public Works ◽  
General Description ◽  
Geological History ◽  
East African ◽  
The Public ◽  
Geographical Society ◽  
History Of ◽  
African Rift ◽  
At Home

The Lake Rudolf Rift Valley Expedition was designed to carry out many different lines of investigation in the Lake Rudolf Basin. One of the chief of these was a study of the geological history of that part of the East African Rift Valley. The expedition was assisted financially by The Royal Society, The Geological Society of London, The Royal Geographical Society, The Percy Sladen Trustees and the Geographical and Geological Sections of the British Association. A general description of the activities of the Expedition was given in a paper read before the Royal Geographical Society (Fuchs 1935). Owing to the tragic loss of two members of the expedition, Dr W. S. Dyson and Mr W. R. H. Martin, two fruitless months were spent searching for them. Consequently a great amount of the work planned for the east side of the lake had to be abandoned. Nevertheless, the considerable distance travelled within the 50,000 sq. miles of the Rudolf Basin has enabled me to make out the chief events of its geological history. I am very much indebted to all those who assisted us in the field and at home, in particular to the Kenya Government, the Officers of the King’s African Rifles, and Mr H. L. Sikes of the Public Works Department; I would also like to thank Mr A. M. Champion, Provincial Commissioner of Turkana, who wholeheartedly assisted us in every way possible both in the field and at home, for he has placed at my disposal his own excellent topographical maps and his extensive observations on the geology of the area. I am also deeply indebted to Professor O. T. Jones, Mr Henry Woods and Mr W. Campbell Smith for their criticisms. Mr Campbell Smith has also given me provisional identifications of the rocks.

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