GEPHE SUMMARY
Gephebase Gene
Entry Status
Published
GepheID
GP00000567
Main curator
Martin
PHENOTYPIC CHANGE
Trait Category
Trait State in Taxon A
Astyanax mexicanus surface
Trait State in Taxon B
Astyanax mexicanus - Pachon cave
Ancestral State
Taxon A
Taxonomic Status
Taxon A
Common Name
Mexican tetra
Synonyms
Mexican tetra; blind cave fish; Astyanax mexicanus (De Filippi, 1853)
Rank
species
Lineage
Show more ... eopterygii; Teleostei; Osteoglossocephalai; Clupeocephala; Otomorpha; Ostariophysi; Otophysi; Characiphysae; Characiformes; Characoidei; Characidae; Characidae incertae sedis; Astyanax clade; Astyanax
NCBI Taxonomy ID
is Taxon A an Infraspecies?
No
Taxon B
Common Name
Mexican tetra
Synonyms
Mexican tetra; blind cave fish; Astyanax mexicanus (De Filippi, 1853)
Rank
species
Lineage
Show more ... eopterygii; Teleostei; Osteoglossocephalai; Clupeocephala; Otomorpha; Ostariophysi; Otophysi; Characiphysae; Characiformes; Characoidei; Characidae; Characidae incertae sedis; Astyanax clade; Astyanax
NCBI Taxonomy ID
is Taxon B an Infraspecies?
Yes
Taxon B Description
Astyanax mexicanus - Pachon cave
GENOTYPIC CHANGE
Generic Gene Name
MC1R
Synonyms
CMM5; MSH-R; SHEP2; MSHR
Sequence Similarities
Belongs to the G-protein coupled receptor 1 family.
UniProtKB
Homo sapiens
GenebankID or UniProtKB
Presumptive Null
Yes
Molecular Type
Aberration Type
Deletion Size
1-9 bp
Molecular Details of the Mutation
2bp deletion resulting in frameshift
Experimental Evidence
Authors
Gross JB; Borowsky R; Tabin CJ
Abstract
The evolution of degenerate characteristics remains a poorly understood phenomenon. Only recently has the identification of mutations underlying regressive phenotypes become accessible through the use of genetic analyses. Focusing on the Mexican cave tetra Astyanax mexicanus, we describe, here, an analysis of the brown mutation, which was first described in the literature nearly 40 years ago. This phenotype causes reduced melanin content, decreased melanophore number, and brownish eyes in convergent cave forms of A. mexicanus. Crosses demonstrate non-complementation of the brown phenotype in F(2) individuals derived from two independent cave populations: Pachón and the linked Yerbaniz and Japonés caves, indicating the same locus is responsible for reduced pigmentation in these fish. While the brown mutant phenotype arose prior to the fixation of albinism in Pachón cave individuals, it is unclear whether the brown mutation arose before or after the fixation of albinism in the linked Yerbaniz/Japonés caves. Using a QTL approach combined with sequence and functional analyses, we have discovered that two distinct genetic alterations in the coding sequence of the gene Mc1r cause reduced pigmentation associated with the brown mutant phenotype in these caves. Our analysis identifies a novel role for Mc1r in the evolution of degenerative phenotypes in blind Mexican cavefish. Further, the brown phenotype has arisen independently in geographically separate caves, mediated through different mutations of the same gene. This example of parallelism indicates that certain genes are frequent targets of mutation in the repeated evolution of regressive phenotypes in cave-adapted species.
Additional References
RELATED GEPHE
Related Genes
Related Haplotypes
1
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