Regressive Evolution in the Mexican Cave Tetra, Astyanax mexicanus

Meredith Protas, Melissa Conrad, Joshua B. Gross, Clifford Tabin, Richard Borowsky

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish (US)
Pages (from-to)452-454
Number of pages3
JournalCurrent Biology
Volume17
Issue number5
DOIs
StatePublished - Mar 6 2007

Fingerprint

Caves
caves
eyes
Quantitative Trait Loci
Pigmentation
quantitative trait loci
pigmentation
Genetic Selection
Fish
Animals
Fishes
natural selection
Melanophores
Taste Buds
Genetic Drift
Costs and Cost Analysis
Crystalline Lens
Darkness
Astyanax mexicanus
Jaw

Keywords

  • EVO_ECOL

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)

Cite this

Regressive Evolution in the Mexican Cave Tetra, Astyanax mexicanus. / Protas, Meredith; Conrad, Melissa; Gross, Joshua B.; Tabin, Clifford; Borowsky, Richard.

In: Current Biology, Vol. 17, No. 5, 06.03.2007, p. 452-454.

Research output: Contribution to journalArticle

Protas, Meredith ; Conrad, Melissa ; Gross, Joshua B. ; Tabin, Clifford ; Borowsky, Richard. / Regressive Evolution in the Mexican Cave Tetra, Astyanax mexicanus. In: Current Biology. 2007 ; Vol. 17, No. 5. pp. 452-454.
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