Mapping and expression of candidate genes for development rate in rainbow trout (Oncorhynchus mykiss)

Development rate has important implications for individual fitness and physiology. In salmonid fishes, development rate correlates with many traits later in life, including life history diversity, growth, and age and size at sexual maturation. In rainbow trout (Oncorhynchus mykiss), a Quantitative Trait Locus (QTL) for embryonic development rate has been detected on chromosome 5 across populations. However, few candidate genes have been identified within this region. In this study, we use gene mapping, gene expression, and quantitative genetic methods to further identify the genetic basis of embryonic developmental rate in O. mykiss. Among the genes located in the region of the major development rate QTL (GHR1, Clock1a, Myd118-1, and their paralogs), all were expressed early in embryonic development (fertilization through hatch), but none were differentially expressed between individuals with the fast- or slow-developing alleles for a major embryonic development rate QTL. In a follow up...