Heritability of fluctuating asymmetry for multiple traits in chinook salmon (Oncorhynchus tshawytscha)

Abstract

The heritability of fluctuating asymmetry (FA) as an indicator of developmental instability is of interest to evolutionary and conservation biologists and is the subject of ongoing controversy. This study examined the inheritance of FA in two groups of fish: domestic chinook salmon (Oncorhynchus tshawytscha) mated in a full-sib design and domestic and wild chinook salmon mated in a half-sib design. Eight traits were measured on the right and left sides of each fish: eye diameter, head length, maxillary length, branchiostegal ray number, pectoral and pelvic fin ray number, and upper and lower gill raker number on the first gill arch. Narrow-sense heritabilities were calculated from parent-offspring regressions for the first group and using sib analysis for the second group. Our data represent the largest breeding program designed to detect heritability of FA in fish reported to date. We found no significant heritability of FA for any of the individual traits examined or for a composite FA index. Our results indicate that FA estimates in chinook salmon will not be confounded by appreciable additive genetic contributions and thus can be reliably used as an environmental and genetic stress indicator.