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Adaptive significance of sex change in the stone loach ( Nemachilus angorae )
Author(s) -
Sari A.
Publication year - 2003
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.2003.216bp.x
Subject(s) - biology , ovotestis , sex change , gonad , zoology , sympatric speciation , sex ratio , population , offspring , ecology , fish <actinopterygii> , demography , fishery , anatomy , pregnancy , sociology , genetics
Previous comparative studies, using multivariate analyses, on two sympatric loaches, Nemachilus angorae and N. malapterurus in Jajroud river, Iran, revealed some degrees of morphological similarity of larger males to female individuals only in the former species. Later, histological studies of testis resulted in observation of some mature oocytes mostly in testes of larger males. Their gonad was similar to ovotestis of hermaphroditic fish. To find out about the sex change in male N. angorae , several hypothesis were tested including: effects of pollutants, interspecific competitions for resources, man‐made habitat alteration, lack of enough rain at least for three years and population structure on sex change. It seems that population structure in N. angorae is an important factor with significant impacts on reproductive behaviour and subsequent changes in both sex and morphology of male individuals. In this case, there is a tendency to have a sex change in favour of less abundant sex (female). This is more pronounced in larger male fish which have higher ability to produce eggs and have no chance to produce offspring in the coming year.