Heritability of vitellogenin in hemolymph, a pre-spawning selectable trait in Penaeus (Litopenaeus) vannamei, has a large genetic correlation with ovary maturity measured as oocytes mean diameter
2009
Ibarra, Ana M. | Famula, Thomas R. | Arcos, Fabiola G.
Vitellogenin, when measured in shrimp hemolymph has been found to reflect the degree of female shrimp ovarian development before eyestalk ablation, and to be a useful predictor of ovarian development after ablation. The present study estimated the heritability and genetic correlations of vitellogenin in hemolymph, and the number and diameter of oocytes in gonads, as a measure of reproductive potential of Pacific white shrimp. Furthermore, we examined whether any of these characters was influenced by the action of a segregating locus of large effect through complex segregation analysis. Shrimps were grown at high density in a raceway, and evaluated at an average weight of 35g. The heritability of vitellogenin in hemolymph (Vtg) and oocytes mean diameter were significant (0.29±12 and 0.23±11), however, the heritability for the number of oocytes (0.11±.09) was not significant. A large genetic correlation was found between Vtg and oocytes mean diameter (0.90±0.08), but not for Vtg and number of oocytes, or for oocytes mean diameter and numbers. Regardless of a significant bimodal distribution being present in the shrimp population for vitellogenin in hemolymph, complex segregation analyses could not detect a major segregating locus for this or any of the traits. Vtg is the first reproductive genetic trait found to predict reproductive capacity of shrimp before eyestalk ablation, and given its high heritability and genetic correlation with oocytes mean diameter, its utilization in selective breeding is expected to allow simultaneous improvement of growth and reproductive capacity in shrimp.
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