Predicting the mating system from phenotypic correlations between life-history and sperm quality traits in the Alpine whitefish Coregonus zugensis

Abstract

The mating behavior and reproductive strategies of Alpine whitefish like Coregonus zugensis (Nüsslin) are poorly understood, probably because they spawn in deep water where direct observations are difficult. In this study, we interpret life-history and sperm quality traits of fish that we caught from their spawning place. We found that males invest heavily into gonadal tissue (up to 5.6% of their body weight), which is, in comparison to other fish, consistent with external fertilization, distinct pairing and moderate to high communal spawning, or no pairing and low to moderate communal spawning. Sperm competition theory and recent experimental studies on other salmonids predict that males optimize ejaculate characteristics in relation to the costs of sperm and the level of competition they have to expect: dominant males are predicted to invest less into ejaculate quality and to have slower spermatozoa than subdominant males. We found that spermatozoa of older males are slower than those of younger males. Moreover, older males have larger breeding tubercles, a secondary sexual trait that has, in some previous studies, been found to be linked to good condition and to good genetic quality. Our results suggest that C. zugensis has age-linked reproductive strategies, that multimale spawning is common, i.e., that sperm competition plays a significant role, and that older males are on average dominant over younger males at the spawning place.

Gonadal alterations in male whitefish Coregonus fatioi: no evidence for genetic damage reducing viability in early life stages

“…In the sample used for the present study, individuals with high fluctuating asymmetry and with at least some types of gonadal alterations were found to have faster sperm than other males ). Thus, and because increased sperm velocity may compensate for social, genetic and/or phenotypic disadvantages (Taborsky 1998, Rudolfsen et al 2006, Rudolfsen et al 2008, gonadal malformations may also be regarded as an indicator of genetic quality and as another phenotypic expression of developmental instability.…”

“…In the sample used for the present study, individuals with high fluctuating asymmetry and with at least some types of gonadal alterations were found to have faster sperm than other males ). Thus, and because increased sperm velocity may compensate for social, genetic and/or phenotypic disadvantages (Taborsky 1998, Rudolfsen et al 2006, Rudolfsen et al 2008, gonadal malformations may also be regarded as an indicator of genetic quality and as another phenotypic expression of developmental instability.Here we tested whether there is a link between the occurrence of gonadal alterations and genetic quality by monitoring an important aspect of offspring fitness, namely embryo viability from fertilization until hatching. If the aberrant development of gonadal tissues is a phenotypic expression of reduced genetic quality, parental individuals displaying gonadal alterations would be expected to sire embryos of reduced viability.…”

Immune activation decreases sperm viability in both sexes and influences female sperm storage

“…Thus, variation in viability appears to be shaped by selection and probably plays a key role in how insect mating systems evolve. Intraspecific variation in sperm viability may be the result of male physiological condition [3,4], male genotype [5], meiotic drive [2], or female mating history [6]. Recent work in vertebrates also suggests that variation may be influenced by a male's current pathogen load [7,8].…”

Offspring performance is linked to parental identity and male breeding ornamentation in whitefish

“…It has been suggested that the primary function of breeding tubercles in whitefish is to maintain contact between individuals during spawning, although the conspicuous white colour and hardness of these ornaments may enable tubercles to be used also as visual and tactile signals (Wiley & Collette, 1970). Even though it is not known whether these tubercles are costly to produce ; but see also Kortet et al, 2003), previous studies have demonstrated that the size and/or number of the breeding tubercles are linked to individual condition (Wedekind, 1992;Rudolfsen et al, 2008), parasite resistance (Kortet et al, 2004b) and male dominance (Kortet et al, 2004a). In addition, Wedekind et al (2001) demonstrated strong maternal and paternal effects in egg mortality of whitefish, and reported a negative association between the size of male breeding tubercles and embryonic mortality (i.e.…”