Sexual selection leads to a tenfold difference in reproductive success of alternative reproductive tactics in male Atlantic salmon

Abstract

The precocious maturation of some male Atlantic salmon (Salmo salar L.) has become a textbook example of alternative mating tactics, but the only estimates of reproductive success available so far are either the collective contribution of precocious males to reproduction in the wild or individual reproductive success in oversimplified experimental conditions. Using genetic parentage analysis on anadromous and precocious potential spawners and their offspring, we quantified components of individual reproductive success of both tactics in a natural population. On average, precocious males produced 2.24 (variance 67.62) offspring, against 27.17 (3080) for anadromous males. For both tactics, most of the variance in reproductive success was due to mating success, with 83% of precocious males having no mate, against 50% for anadromous males. Body size increased reproductive success of anadromous males and tended to decrease precocious males' reproductive success. Although these results do not solve the coexistence of alternative reproductive tactics (ARTs) in Atlantic salmon, their inclusion in comprehensive models of lifetime reproductive success should shed light on the evolution of precocious maturation in Atlantic salmon and its effect on the selection of phenotypic traits.

Estimating the effective number of breeders from single parr samples for conservation monitoring of wild populations of Atlantic salmon Salmo salar

“…We also took advantage of the availability of observations obtained previously for the S. salar River Nivelle population for the 2010 and 2011 reproductive seasons (Tentelier et al, ) to assess: the effect of YOY sampling spatial extent [whole river in the present study and upper section of the river in Tentelier et al . ()]; sampling intensity [shallow in this study and exhaustive around spawning sites in Tentelier et al .…”

“…()]; sampling intensity [shallow in this study and exhaustive around spawning sites in Tentelier et al . ()]; time of year [9 months after spawning in autumn in the present study and 3 months after spawning in early spring in Tentelier et al, ()], on estimation of N b . Effects of sampling spatial extent and sampling intensity were assessed by direct comparison of N b estimates with Tentelier et al .…”

“…Effects of sampling spatial extent and sampling intensity were assessed by direct comparison of N b estimates with Tentelier et al . (). To control for differences in sampling strategy when testing the effect of sampling time of year on estimation of N b , however, COLONY was used to estimate N b from the subsample of YOY genotyped in this study but electrofished upstream of Olha only (Fig.…”

Genetic architecture of threshold reaction norms for male alternative reproductive tactics in Atlantic salmon (Salmo salar L.)

“…While mature male parr reproductive contribution can exceed anadromous male reproductive contribution at the population level (e.g. 25 to 56%19 and up to 87%21 of male reproductions in the Nivelle population in south of France), mature male parr individual reproductive success is far lower than anadromous male individual reproductive success due to a reduced matting success of mature male parr19. Evidence from experimental studies including artificial crosses followed by rearing in laboratory conditions and from studies in natural populations has demonstrated a genetic component for early male maturation in S. salar 15222324252627.…”

Testing mate choice and overdominance at MH in natural families of Atlantic salmon Salmo salar

“…Instead of artificial breeding, this study involved samples of naturally breeding adults (both anadromous breeders and mature male parr) and their offspring. Sampling procedure and family reconstruction are described in Tentelier et al . (2016 a , b ).…”