Spermatozoal competition in common carp (Cyprinus carpio): what is the primary determinant of competition success?

Abstract

The percentage of sperm motility (92-100%), spermatozoan velocity (112 -163 mm·s 21 ) and control hatching rates (83-96%) were evaluated for each of six gold and five green male common carp (Cyprinus carpio). In all 30 possible paired combinations of sperm-competition tests, hatching rates of 90 -97% were achieved. The mean percentage of offspring sired was strongly influenced by the male used (P < 0.001, R 2 5 0.91). The best male sired an average of 88% of the offspring in its competition tests, and the worst male sired only 5%. Spermatozoan-quality parameters could explain only part of the variation in male competitive ability. The male effects alone explained 91.4% of the observed variance, consisting of 17.1% explained by spermatozoan motility and 32.5% by control hatching rates in single fertilizations. Undetermined male effects explained 41.8%. The velocity of spermatozoa had no effect on the outcome of sperm competition. Neither was there any link between spermatozoan velocity and hatching rate in a control hatching test, whereas there was an effect of motility on hatching rate in this same test.Reproduction ( IntroductionSperm competition occurs when the spermatozoa of several males compete for fertilization. Competition is a major force for spermatozoan selection, but its implications for mating systems and on life-history evolution are only just beginning to be understood (Parker 1998, Gage et al. 2004. Trade-offs between gamete characteristics and relative gametic investment has been modelled by evolutionary stable strategy (ESS) approaches, when the optimal strategy for a male depends on the strategy adopted by other individuals in the population , Parker 1998, Petersen & Warner 1998. All of the models assume that males obtain more fertilization success by releasing more sperm, this being done at a cost to investment in other fitness-enhancing functions such as growth, finding additional males, investment in female function, mate defence, territoriality or releasing more sperm in other spawnings. As applied to fish, sperm-competition trials with paternity analysis have been conducted in several salmonid species (Gage et al. 1995, Gile & Ferguson 1995, Liley et al. 2002 and recently also in cyprinids (Kortet et al. 2004, Reichard et al. 2004a, 2004b or other species such as bluegill sunfish (Lepomis macrochirus; Burness et al. 2004). In rainbow trout (Oncorhynchus mykiss) male potency, defined as the ability of males to sire progeny when their sperm is pooled with that of other males, was not affected by the female gametes used, and decreased significantly when sperm concentrations were equalized (Gile & Ferguson 1995). Sperm vary in morphology, behaviour (speed, trajectory, percentage of sperm motility, etc.) and longevity in fishes. Currently, the mechanism of this variation is poorly explained (Cosson et al. 1999). There appear to be intraspecific differences that may correlate with male-mating type in Atlantic salmon (Salmo salar; Gage et al. 1995). Fishes show one of the widest ranges ...

Sperm characteristics and competitive ability in farmed and wild cod

“…Theoretically, the probability of a sperm encountering an egg is a function of sperm swimming speed, gamete concentration and egg target area (Levitan 2000, Riffell & Zimmer 2007. Sperm density (spermatocrit) has been shown to positively influence male reproductive success in a number of teleost species, including cod (Rakitin et al 1999b), bluegill Lepomis macrochirus (Stoltz & Neff 2006) and common carp Cyprinus carpio (Linhart et al 2005). Wild males had a higher VCL both early and late in their spawning period, and had significantly higher spermatocrit values early and a tendency towards higher values late in their spawning period (Fig.…”

The genetic basis of traits regulating sperm competition and polyandry: can selection favour the evolution of good- and sexy-sperm?

“…This link between sperm viability and male sexual ornamentation in guppies may explain why paternity is biased towards highly ornamented males when the number of sperm from competing males is held constant (Evans et al 2003). Other measures of sperm quality, including sperm mobility (ability to penetrate an inert medium), have been implicated in meditating paternity success in chickens (Birkhead et al 1999), while sperm swimming speeds (Gage et al 2004) and the percentage of motile sperm (Linhart et al 2005) are known to regulate competitive fertilization success in externally fertilizing fishes. Among rodents, sperm competition intensity covaries positively with the ability of sperm to become capacitated and undergo the acrosome reaction, both of which are important prerequisites to fertilization .…”

Do male secondary sexual characters signal ejaculate quality? A meta‐analysis

“…Studies of individual species have also reported a positive relationship between sperm swimming speed and ejaculate competitiveness (e.g. Birkhead et al ., ; Gage et al ., ; Linhart et al ., ; Pizzari et al ., ; Gasparini et al ., 2010 b ; Boschetto, Gasparini & Pilastro, ; Beausoleil et al ., ; but see Dziminski et al ., ; Smith, ). By extension, it is assumed that faster swimming sperm will elevate fertility because this increases the likelihood of sperm reaching eggs before they die.…”