Alternative Male Reproductive Phenotypes Affect Offspring Growth Rates in Chinook Salmon

Abstract

Male age at maturity in Chinook salmon Oncorhynchus tshawytscha is a heritable trait in which the physiological “decision” to mature depends on an individual's exceeding a body size or condition threshold at critical developmental periods. In Chinook salmon, high juvenile growth rates promote the so called “jack” male life history. Jack males mature 1 year earlier than the youngest females in a population and are substantially smaller than older (hereafter, “adult”) males from the same population. We tested the hypothesis that the offspring of jack Chinook salmon males grow faster than the offspring of adult males, consistent with the heritability for age at maturity already demonstrated for this species. We controlled for maternal effects by artificially spawning individual jack and adult males with the same female, incubating the eggs, and testing offspring growth and survival in a common, quasinatural stream environment. Paternal life history had a significant effect on final length and weight over all stream channel sections combined. The mean difference in body size between the offspring of jack and adult males ranged from essentially none to 31% among the eight stream channel sections. The size differences we detected could significantly affect which fish mature and thereby suggest that paternal effects on juvenile growth rate constitute a plausible proximate mechanism in maintaining life history diversity in Chinook salmon. Maternal body size was positively correlated with offspring growth rate and egg size was negatively correlated with growth rate, suggesting that fairly complex mechanisms regulate the growth rate through early ontogeny. The effect of sire life history on offspring growth is consistent with estimates of high heritability for age at maturity in Chinook salmon and a genetic effect of alternative mating tactics on offspring performance.

Evidence for ontogenetically and morphologically distinct alternative reproductive tactics in the invasive Round Goby Neogobius melanostomus

“…Individuals born in the same year at different periods will thus have a different body size at the start of their first breeding season [11]. When born early in the season, individuals can become parental males at the start of their breeding season [46], or they can start by adopting a sneaking tactic [47,48]. In salmonids it was found that individuals that grow quicker and mature at an earlier age adopt a sneaking tactic (“jacks”) [48].…”

Evidence that Marine Temperatures Influence Growth and Maturation of Western Alaskan Chinook Salmon

“…However, it also must be noted that our estimates of SW3 and SW4 are not completely independent measures because variable portions of the population mature before the third year of marine residency. Although growth rate is largely determined by the environment, there is likely a genetic effect driven by differences in behavior and the allocation of energy (e.g., Berejikian et al 2011). Thus, if a larger number of faster-growing fish matures earlier, this could have a negative effect on our estimates of later growth because the faster-growing fish are removed from the population.…”

The effects of paternal reproductive tactic and rearing environment on juvenile variation in growth as mediated through aggression and foraging behaviours of Chinook salmon (Oncorhynchus tshawytscha)

“…(), individuals raised in an accelerated growth (i.e., high temperature) environment were more likely to grow at a faster rate and precociously sexually mature compared with individuals raised in a control environment, and Berejikian et al. () demonstrated that jack sires produced offspring with higher growth rates prior to sexual maturation compared with hooknose sires that then were more likely to precociously sexually mature.…”

“…For indeterminate growers, variation in growth amongst individuals within a species often exists (Taborsky, 2008) and is influenced by environmental factors such as food availability (Ryer & Olla, 1996;Vainikka et al, 2012), physiological factors such as growth efficiency or metabolic rate (Higgins, 1985;Skalski, Picha, Gilliam, & Borski, 2005) and behavioural factors such as dominance or aggression (Huntingford, Metcalfe, Thorpe, Graham, & Adams, 1990;Metcalfe, 1998), or by genetic factors, including maternal and paternal genetic effects (Berejikian, Van Doornik, & Atkins, 2011;Chernoff & Curry, 2007;Eilertsen, Bardsen, Liljedal, & Folstad, 2009;Garant, Dodson, & Bernatchez, 2003;Martyniuk, Perry, Mogahadam, Ferguson, & Danzmann, 2003). Ultimately, variation in growth rates leads to differential body size, and is one of the driving mechanisms underlying individual specialization including the adoption of alternative life-history pathways by individuals within a species (Bolnick et al, 2003).…”