Genetic Basis of Variation in Morphological and Life-History Traits of a Wild Population of Pink Salmon

Abstract

Understanding the genetic basis of phenotypic variation is essential for predicting the direction and rate of phenotypic evolution. We estimated heritabilities and genetic correlations of morphological (fork length, pectoral and pelvic fin ray counts, and gill arch raker counts) and life-history (egg number and individual egg weight) traits of pink salmon (Oncorhynchus gorbuscha) from Likes Creek, Alaska, in order to characterize the genetic basis of phenotypic variation in this species. Families were created from wild-caught adults, raised to the fry stage in the lab, released into the wild, and caught as returning adults and assigned to families using microsatellite loci and a growth hormone locus. Morphological traits were all moderately to highly heritable, but egg number and egg weight were not heritable, suggesting that past selection has eliminated additive genetic variation in egg number and egg weight or that there is high environmental variance in these traits. Genetic correlations were similar for nonadjacent morphological traits and adjacent traits. Genetic correlations predicted phenotypic correlations fairly accurately, but some pairs of traits with low genetic correlations had high phenotypic correlations, and vice versa, emphasizing the need to use caution when using phenotypic correlations as indices of genetic correlations. This is one of only a handful of studies to estimate heritabilities and genetic correlations for a wild population.

Fisheries-induced evolution: present status and future directions

“…Nevertheless, a study into the potential for sea ranching of Atlantic salmon Salmo salar obtained a heritability of 0.36 for body weight after 1 winter at sea, similar to that found in experimental farms (Jónasson et al 1997). In a similar way, Funk et al (2005) were able to estimate heritabilities and genetic correlations of morphological and life-history traits of pink salmon Oncorhynchus gorbuscha on their return from the sea to spawn. Heritabilities of length were approximately 0.4; however, those of egg number and weight -the traits most closely related to fitnesswere not significantly different from zero.…”

“…The best evidence comes from the studies on Atlantic salmon and pink salmon mentioned earlier (Jónasson et al 1997, Funk et al 2005). Other evidence is more circumstantial because it is based on heritability estimates on growth in experimental conditions.…”

“…In practice, genetic correlations are hard to estimate, but some clues may be obtained from the phenotypic correlations of traits (Cheverud 1988, Roff 1995. For example, Funk et al (2005) found a positive relationship between genetic and phenotypic correlations of traits in pink salmon; however, they suggested caution in adopting this approach because the relationship was sometimes lost.…”

Intraspecific Variation in a Predator Affects Community Structure and Cascading Trophic Interactions

“…We have not assessed the heritability of gape and gill raker spacing in alewives, but these foraging traits are highly heritable (Day et al 1994, Foote et al 1999, Funk et al 2005 and respond rapidly to selection in many fish species (Nursall 1974, Schluter andMcPhail 1992). In our populations, differences in gape width and gill raker spacing were maintained when anadromous and landlocked alewives were raised in common garden mesocosm experiments for two months, suggesting that morphological differences have an important genetic component (Appendix A).…”

Paradoxes of Aging

“…In fact, female salmon have 1,000-2,000 eggs. 43 And only one female must survive until reproduction to keep the population constant. Thus, only one out of hundreds of animals dies after reproduction from aging.…”