Altitudinal variation for B chromosome frequency in the characid fish Astyanax scabripinnis

Author(s)

Néo‚ D.M. ; Moreira Filho‚ O. ; Camacho‚ J.P.M.

• Document type: Journal article
• Source: HEREDITY; v. 85, n. 2, p. 136-141, 2000.

Abstract

The analysis of three populations of the characid fish Astyanax scabripinnis located at different altitudes along the same stream has revealed the presence of a macro B chromosome in two high-altitude populations (1800 m and 1920 m) but its absence from a low-altitude population (700 m). Because the stream flows through very rugged mountains, with numerous falls ensuring that any gene flow occurs downstream only, the absence of B chromosomes from the low-altitude populations is best interpreted in the light of the parasitic theory of B chromosome evolution. Under this theory, we would expect B chromosomes to be more frequent where environmental conditions are more favourable for the species, because Bs are best tolerated there. The widespread presence of these B chromosomes in numerous Brazilian river headwaters, which are the preferred habitat for this species, support this possibility. (AU)

• FAPESP's process: 98/07271-8 - Juan Pedro Martínez Camacho | Universidad de Granada - Spain
• Grantee: Orlando Moreira Filho
• Support Opportunities: Research Grants - Visiting Researcher Grant - International