Journal Article
Regression of dark color in subterranean fishes involves multiple mechanisms: response to hormones and neurotransmitters
Grempel, R.G., Trajano, E. and Visconti, M.A.
Record Number:
4774
Year:
2020
Journal:
Neotropical Ichthyology
Pages:
e190120
Volume:
18
Abstract:
Organisms with source-populations restricted to the subterranean biotope
(troglobites) are excellent models for comparative evolutionary studies, due
to their specialization to permanent absence of light. Eye and dark pigment
regression are characteristics of most troglobites. In spite of the advance in
knowledge on the mechanisms behind eye regression in cave fishes, very little
is known about pigmentation changes. Studies were focused on three species of
the genus Pimelodella. Exemplars of the troglobitic P. spelaea and P. kronei were
compared with the epigean (surface) P. transitoria, putative sister-species of the
latter. Melanophore areas and densities are significantly lower in the troglobitic
species. Evaluating the in vitro response of these cells to adrenaline, acetylcholine
and MCH, we observed a reduced response in both troglobites to adrenaline. The
same trend was observed with MCH, but not statistically significant. No response
to acetilcholine was detected in all the three. Contrary to expectations, even
though eye-regression in P. spelaea was much lower than in P. kronei, pigmentation
regression was more advanced. Multiple mechanisms of loss showing a mosaic of
traits in troglobitic fishes are discussed here.
Keywords: Adrenaline, Melanin Concentrating Hormone, Melanophores,
Physiology of Pigmentation, Troglobitic Fish.
Times Cited:
2