Brain size variation in extremophile fish : local adaptation versus phenotypic plasticity. / Eifert, C.; Farnworth, M.; Schulz-Mirbach, Tanja; Riesch, Rüdiger; Bierbach, David; Klaus, S.; Wurster, A.; Tobler, M.; Streit, B.; Indy, J. R.; Arias-Rodriguez, L.; Plath, M.

In: Journal of Zoology , Vol. 295, No. 2, 02.2015, p. 143-153.

Research output: Contribution to journalArticlepeer-review

  • C. Eifert
  • M. Farnworth
  • Tanja Schulz-Mirbach
  • Rüdiger Riesch
  • David Bierbach
  • S. Klaus
  • A. Wurster
  • M. Tobler
  • B. Streit
  • J. R. Indy
  • L. Arias-Rodriguez
  • M. Plath


The brain is a plastic organ, and so intraspecific studies that compare results obtained from wild individuals with those from common-garden experiments are crucial for studies aiming to understand brain evolution. We compared volumes of brain regions between reproductively isolated populations of a neotropical fish, Poecilia mexicana, that has locally adapted to perpetual darkness (Cueva Luna Azufre), toxic hydrogen sulphide in a surface stream (El Azufre) or a combination of both stressors (Cueva del Azufre). Wild fish showed habitat-dependent differ- ences: enlarged telencephalic lobes and reduced optic tecta were found in fish living in darkness and sulphidic waters, in darkness without hydrogen sulphide or exposed to light and sulphide; fish from the sulphidic cave additionally showed enlarged cerebella. Comparison with common-garden reared fish detected a general decrease in brain size throughout populations in the lab, and little of the brain size divergence between lab-reared ecotypes that was seen in wild-caught fish. The pronounced differences in brain region volumes between ecotypes in the wild might be interpreted within the framework of mosaic evolution; however, the outcomes of common-garden experiments indicate a high amount of phenotypic plasticity. Our study thus highlights the importance of combining the investigation of brain size in wild populations with common-garden experiments for answering questions of brain evolution.
Original languageEnglish
Pages (from-to)143-153
Number of pages11
JournalJournal of Zoology
Issue number2
Early online date13 Nov 2014
Publication statusPublished - Feb 2015
This open access research output is licenced under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

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