TY - JOUR
T1 - Regressive Evolution in the Mexican Cave Tetra, Astyanax mexicanus
AU - Protas, Meredith
AU - Conrad, Melissa
AU - Gross, Joshua B.
AU - Tabin, Clifford
AU - Borowsky, Richard
N1 - Funding Information:
This study was supported by grants from the United States National Science Foundation (IBN0217178; C.T. and R.B.) and the United States National Institutes of Health (1RO3EYE016783-01; R.B.). We thank A. Korol for invaluable advice on the analyses, L. Mekiou for numerous contributions to the maintenance and phenotyping of the animals, B. Borowsky, C. Desplan, D. Fitch, M. Purugganan, M. Siegal, and A. Swaroop for fruitful discussion and criticism, and H. Ajmera and L. Nirenstein for phenotyping.
PY - 2007/3/6
Y1 - 2007/3/6
N2 - The evolutionary forces driving the reduction of eyes and pigmentation in cave-adapted animals are unknown; Darwin famously questioned the role of natural selection in eye loss in cave fishes: "As it is difficult to imagine that eyes, although useless, could be in any way injurious to animals living in darkness, I attribute their loss wholly to disuse" [1]. We studied the genetics of eye and pigmentation regression in the Mexican cave tetra, Astyanax mexicanus, by mapping and quantitative trait loci (QTL) analysis. We also mapped QTL for the putatively constructive traits of jaw size, tooth number, and numbers of taste buds. The data suggest that eyes and pigmentation regressed through different mechanisms. Cave alleles at every eye or lens QTL we detected caused size reductions, consistent with evolution by natural selection but not with drift. QTL polarities for melanophore number were mixed, however, consistent with genetic drift. Arguments against a role for selection in the regression of cave-fish eyes cited the insignificant cost of their development [2, 3], but we argue that the energetic cost of their maintenance is sufficiently high for eyes to be detrimental in the cave environment. Regression can be caused either by selection or drift.
AB - The evolutionary forces driving the reduction of eyes and pigmentation in cave-adapted animals are unknown; Darwin famously questioned the role of natural selection in eye loss in cave fishes: "As it is difficult to imagine that eyes, although useless, could be in any way injurious to animals living in darkness, I attribute their loss wholly to disuse" [1]. We studied the genetics of eye and pigmentation regression in the Mexican cave tetra, Astyanax mexicanus, by mapping and quantitative trait loci (QTL) analysis. We also mapped QTL for the putatively constructive traits of jaw size, tooth number, and numbers of taste buds. The data suggest that eyes and pigmentation regressed through different mechanisms. Cave alleles at every eye or lens QTL we detected caused size reductions, consistent with evolution by natural selection but not with drift. QTL polarities for melanophore number were mixed, however, consistent with genetic drift. Arguments against a role for selection in the regression of cave-fish eyes cited the insignificant cost of their development [2, 3], but we argue that the energetic cost of their maintenance is sufficiently high for eyes to be detrimental in the cave environment. Regression can be caused either by selection or drift.
KW - EVO_ECOL
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U2 - 10.1016/j.cub.2007.01.051
DO - 10.1016/j.cub.2007.01.051
M3 - Article
C2 - 17306543
AN - SCOPUS:33847295149
SN - 0960-9822
VL - 17
SP - 452
EP - 454
JO - Current Biology
JF - Current Biology
IS - 5
ER -