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| Author(s): |
Renato Grotta Grempel
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2011-09-16 |
| Examining board members: |
Maria Aparecida Visconti;
Maria Elina Bichuette;
Fernando Ribeiro Gomes
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| Advisor: | Maria Aparecida Visconti |
| Abstract | |
The cave environments can be seen as a natural experiment of exclusion of certain ecological factors, among which the most important is the absence of photoperiod. The loss or reduction of eyes and skin melanin pigmentation in relation to individuals living on the surface are the most common examples of the changes undergone by the species exclusively subterraneous. Changes in characteristics related to the ocular system have always received great attention from researchers. However, publications on the pigmentation in these organisms are relatively uncommon, with a very small taxonomic range. Our experiments were conducted with three species of the same genre: Pimelodella kronei and P. spelaea, living in cave environments, and P.transitoria, living in surface. We aim to compare if there is a pattern that correlates the degree of reduction of the pigment with the characteristics of pigment cells. As expected, P. spelaea and Pimelodella kronei showed smaller size and lower density of melanophores than its counterpart epigeal, P. transitória. Our results did not suggest a positive correlation between the degree of troglomorfism measured by macroscopic characteristics, and physiological response observed in cave specimens. The variability observed in the states of pigmentation in Brazilian troglomorfic fish is compatible with neutral hypotheses involving selective pressures, supporting therefore the neutralist model. (AU) | |