Additive and non-additive genetic components of the jack male life history in Chinook salmon (Oncorhynchus tshawytscha)

Abstract

Chinook salmon, Oncorhynchus tshawytscha, exhibit alternative reproductive tactics (ARTs) where males exist in two phenotypes: large "hooknose" males and smaller "jacks" that reach sexual maturity after only 1 year in seawater. The mechanisms that determine "jacking rate"-the rate at which males precociously sexually mature-are known to involve both genetics and differential growth rates, where individuals that become jacks exhibit higher growth earlier in life. The additive genetic components have been studied and it is known that jack sires produce significantly more jack offspring than hooknose sires, and vice versa. The current study was the first to investigate both additive and non-additive genetic components underlying jacking through the use of a full-factorial breeding design using all hooknose sires. The effect of dams and sires descendant from a marker-assisted broodstock program that identified "high performance" and "low performance" lines using growth- and survival-related gene markers was also studied. Finally, the relative growth of jack, hooknose, and female offspring was examined. No significant dam, sire, or interaction effects were observed in this study, and the maternal, additive, and non-additive components underlying jacking were small. Differences in jacking rates in this study were determined by dam performance line, where dams that originated from the low performance line produced significantly more jacks. Jack offspring in this study had a significantly larger body size than both hooknose males and females starting 1 year post-fertilization. This study provides novel information regarding the genetic architecture underlying ARTs in Chinook salmon that could have implications for the aquaculture industry, where jacks are not favoured due to their small body size and poor flesh quality.

Precocious Maturation of Hatchery‐Raised Spring Chinook Salmon as Age‐2 Minijacks Is Not Detectably Affected by Sire Age

“…2011; although see also Forest et al. 2016), and other studies have reported that genes involved in controlling age at maturation are associated with male‐specific regions in the genome of Chinook Salmon (Heath et al. 2002; McKinney et al.…”

“…In addition to these physiological factors stimulating precocious maturation, numerous studies also indicate that age at maturity among salmonids, including precocious maturity, has a genetic basis. In adult salmonids specifically, a positive correlation between age at maturity of broodstock and age at maturity of their progeny has been observed, with estimates of heritability for age at maturation reported as being low in some studies (Silverstein and Hershberger 1992;Forest et al 2016) but relatively high in others (Thorpe et al 1983;Gjerde 1984;Iwamoto et al 1984;Gall et al 1988;Hankin et al 1993;Hard 1995;Heath et al 2002;Berejikian et al 2011). Additionally, recent studies have provided evidence for the direct association of salmonid age at adult maturity with particular molecular genetic markers (Heath et al 2002;Pedersen et al 2013;Ayllon et al 2015Ayllon et al , 2019Barson et al 2015;Christensen et al 2017;Czorlich et al 2018;McKinney et al 2020McKinney et al , 2021Waters et al 2021).…”

“…In adult salmonids specifically, a positive correlation between age at maturity of broodstock and age at maturity of their progeny has been observed, with estimates of heritability for age at maturation reported as being low in some studies (Silverstein and Hershberger 1992; Forest et al. 2016) but relatively high in others (Thorpe et al. 1983; Gjerde 1984; Iwamoto et al.…”

Sex-Specific Stress Tolerance in Embryos of Lake Char (Salvelinus umbla)

“…Parental effects on embryo and larval performance have been repeatedly analyzed in other salmonids, usually based on fullfactorial breeding experiments with sufficient replication on the maternal and the paternal sides and large numbers of embryos that were often singly reared as in the present study (recent examples include Clark et al, 2016;Forest et al, 2016;Marques da Cunha et al, 2019;Nusbaumer et al, 2021c). Such experiments allow separating and quantifying the variance components and hence testing, for example, for the evolutionary potential of natural populations to adapt to changing environments (Lynch and Walsh, 1998).…”

A potential role for restricted intertactical heritability in preventing intralocus conflict

“…In another Coho study, heritabilities for length based only on the dam component of variance decreased consistently between 5 and 11 months posthatching (Silverstein & Hershberger, 1994). In a study of Chinook salmon, maternal effect on body size (weight) disappeared by 200 days after emergence (Heath et al, 1999), and another study found no significant maternal effect found on jacking rate (Forest et al, 2016). In concordance with our study, Iwamoto et al (1984) found that, in Coho salmon reared for one year, maternal effects explained the variation in length of female offspring, while paternal effects explained more variation in the length of male offspring.…”