Female preference for male body size in brown trout, Salmo trutta: is big still fashionable?

Mating with attractive or dominant males is often predicted to offer indirect genetic benefits to females, but it is still largely unclear how important such non-random mating can be with regard to embryo viability. We sampled a natural population of adult migratory brown trout (Salmo trutta), bred them in vitro in a half-sib breeding design to separate genetic from maternal environmental effects, raised 2098 embryos singly until hatching, and exposed them experimentally to different levels of pathogen stress at a late embryonic stage. We found that the embryos' tolerance to the induced pathogen stress was linked to the major histocompatibility complex (MHC) of their parents, i.e. certain MHC genotypes appeared to provide better protection against infection than others. We also found significant additive genetic variance for stress tolerance. Melanin-based dark skin patterns revealed males with 'good genes', i.e. embryos fathered by dark coloured males had a high tolerance to infection. Mating with large and dominant males would, however, not improve embryo viability when compared to random mating. We used simulations to provide estimates of how mate choice based on MHC or melanin-based skin patterns would influence embryos' tolerance to the experimentally induced pathogen stress.

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“…2008b), and body size that was found to influence mating success in this species (Jacob et al. 2007; Labonne et al. 2009).…”

Section: Introductionmentioning

confidence: 92%

“…A potential quality indicator could be body size if it reveals age and hence good survival, or if it reveals fast growth and hence some sort of health and vigor (as discussed in Jacob et al. 2007; Labonne et al. 2009).…”

Section: Introductionmentioning

confidence: 99%

Effects of different mating scenarios on embryo viability in brown trout

et al. 2010

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“…Achieved length and age of trout in our studied populations equal or even surpass that from other populations defined as large piscivorous brown trout (Campbell, ; Jensen et al., ; Mangel, ). Selection for size is reinforced because females prefer mating with even larger males (Labonne et al., ), promoting assortative mating in suitable habitat, that is, larger fish require larger habitats. Although the low‐genetic differentiation among ecotypes in P3 indicates that the reproductive barrier is not absolute, alternative reproductive strategies (i.e., sneaking, Avise, Jones, Walker, & DeWoody, ), likely have limited impact on genetic structure.…”

Section: Discussionmentioning

confidence: 99%

Life histories and ecotype conservation in an adaptive vertebrate: Genetic constitution of piscivorous brown trout covaries with habitat stability

Wollebæk

Heggenes

Røed

2018

Ecology and Evolution

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Ecotype variation in species exhibiting different life history strategies may reflect heritable adaptations to optimize reproductive success, and potential for speciation. Traditionally, ecotypes have, however, been defined by morphometrics and life history characteristics, which may be confounded with individual plasticity. Here, we use the widely distributed and polytypic freshwater fish species brown trout (Salmo trutta) as a model to study piscivorous life history and its genetic characteristics in environmentally contrasting habitats; a large lake ecosystem with one major large and stable tributary, and several small tributaries. Data from 550 fish and 13 polymorphic microsatellites (H e = 0.67) indicated ecotype‐specific genetic differentiation (θ = 0.0170, p < .0001) among Bayesian assigned small riverine resident and large, lake migrating brown trout (>35 cm), but only in the large tributary. In contrast, large trout did not constitute a distinct genetic group in small tributaries, or across riverine sites. Whereas life history data suggest a small, river resident and a large migratory piscivorous ecotype in all studied tributaries, genetic data indicated that a genetically distinct piscivorous ecotype is more likely to evolve in the large and relatively more stable river habitat. In the smaller tributaries, ecotypes apparently resulted from individual plasticity. Whether different life histories and ecotypes result from individual plasticity or define different genetic types, have important consequence for conservation strategies.

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“…Now as to why female body size, for instance, had a negative effect on visit and gamete release probability, and no positive effect on offspring number, we must turn to the behavioral knowledge of the species. In particular, assortative or disassortative visit and mating, be it the result of mate choice, intrasexual competition or chance, is possible in brown trout (Petersson et al 1999, Labonne et al 2009): bigger females tend to be aggressively monopolized by bigger males, thereby limiting their access to a higher number of potential mates. Unfortunately our dataset is too small to properly infer the effect of interaction between male and female phenotype on the different components of reproductive success (Moshgani and Dooren 2011), though it is very easy to implement in the model (on our dataset, model including interaction did not converge at all).…”

Section: What Is Mating Success?mentioning

confidence: 99%

“…The conditional structure linking the successive components of pairwise reproductive success is the key to extract information from both behavioral and genetic data: presence of offspring from a pair of parents implies the male having visited the female and released his gametes concomitantly with hers, even if these are absent from behavioral data, whereas observation of gamete release despite the absence of common offspring allows distinguishing between zero-value due pre-copulatory and post-copulatory mechanisms. We illustrate the model using a reproduction experiment data for Salmo trutta as a case study, with body size as an example of phenotypic covariate as it is known to be involved in sexual selection in salmonids (Jacob et al 2007, Labonne et al 2009) and could therefore have an effect on each of these components of sexual selection. Brown trout mating system is polygynandrous (Labonne et al 2013).…”

Section: Introductionmentioning

confidence: 99%

With our powers combined: integrating behavioral and genetic data to estimate mating success and sexual selection

Gauthey¹,

Tentelier²,

Lepais³

et al. 2017

ReEco

Self Cite

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The analysis of sexual selection classically relies on the regression of individual phenotypes against the marginal sums of a males × females matrix of pairwise reproductive success, assessed by genetic parentage analysis. When the matrix is binarized, the marginal sums give the individual mating success. Because such analysis treats male and female mating/reproductive success independently, it ignores that the success of a male × female sexual interaction can be attributable to the phenotype of both individuals. Also, because it is based on genetic data only, it is oblivious to unproductive matings, which may be documented by behavioral observations. To solve these problems, we propose a statistical approach which combines matrices of offspring numbers and behavioral observations. It models reproduction on each mating occasion of a mating season as three stochastic and interdependent pairwise processes, each potentially affected by the phenotype of both individuals and by random individual effect: visit of a female by a male, concomitant gamete emission, and offspring production. Applied to data from a mating experiment on brown trout, the model yielded different results from the classical regression analysis, with only a negative effect of female body size on the probability of visit and gamete release, while the classical approach based on regression found a positive effect of male size on the number of both visits and offspring, and no effect of female size. Because the general structure of the model can be adapted to other partitioning schemes of the reproductive process, it can be used for a variety of biological systems where behavioral and genetic data are available.

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Female preference for male body size in brown trout, Salmo trutta: is big still fashionable?

Cited by 26 publications

References 33 publications

Effects of different mating scenarios on embryo viability in brown trout

Effects of different mating scenarios on embryo viability in brown trout

Life histories and ecotype conservation in an adaptive vertebrate: Genetic constitution of piscivorous brown trout covaries with habitat stability

With our powers combined: integrating behavioral and genetic data to estimate mating success and sexual selection

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