Contrasting growth strategies of pond versus marine populations of nine-spined stickleback (Pungitius pungitius): a combined effect of predation and competition?

Abstract

Gigantism in isolated ponds in the absence of sympatric fish species has previously been observed in nine-spined sticklebacks (Pungitius pungitius). Patterns in sexual size dimorphism suggested that fecundity selection acting on females might be responsible for the phenomenon. However, the growth strategy behind gigantism in pond sticklebacks has not been studied yet. Here, we compared von Bertalanffy growth parameters of four independent nine-spined stickleback populations reared in a common laboratory environment: two coastal marine (typical size) and two pond (giant size) populations. We found that both pond populations had larger estimated final size than marine populations, which in turn exhibited higher intrinsic growth rates than the pond populations. Female growth strategies were more divergent among marine and pond populations than those of males. Asymptotic body size and intrinsic growth rate were strongly negatively correlated. Hence, pond versus marine populations exhibited different growth strategies along a continuum. Our data suggest that quick maturation-even with the cost of being small (low fecundity)-is favoured in marine environments. On the contrary, growth to a giant final size (high fecundity)-even if it entails extended growth period-is favoured in ponds. We suggest that the absence (ponds) versus presence (marine environment) of sympatric predatory fish species, and the consequent change in the importance of intraspecific competition are responsible for the divergence in growth strategies. The sex-dependence of the patterns further emphasizes the role of females in the body size divergence in the species. Possible alternative hypotheses are also discussed.

Ecological causes of morphological evolution in the three‐spined stickleback

“…The only other study of which we are aware linking stickleback morph with predation regime and antipredator behavior did not demonstrate a significant effect, though the study failed to replicate at the population level (Grand 2000). Behavioral differences among populations of the related nine-spined stickleback have also been attributed to predator pressure (Herczeg et al 2009, 2012). The interaction between morph and predator abundance in the present study was not statistically significant, but was sufficiently low to warrant further investigation of a possible divergent response of different morphs to predation.…”

Ontogenetic and evolutionary effects of predation and competition on nine‐spined stickleback (Pungitius pungitius) body size

“…At any rate, only pond females were clearly unaffected by the olfactory cues of a common stickleback predator. Interestingly, they are the sex that is suspected to drive the evolution of gigantism observed in ponds (Herczeg, Gonda & Merilä 2010a; Herczeg et al. 2012).…”

“…The aim of this study was to examine how local selective pressures, predation and variability in resources/competition have shaped the expression of plasticity towards variation in the food supply and perceived predation risk using nine‐spined stickleback as a model. Because females seem to drive body size evolution in the species (Herczeg, Gonda & Merilä 2010a; Herczeg et al. 2012), we were also interested to see whether there is divergence in plasticity between sexes.…”

Intraspecific variation in behaviour: effects of evolutionary history, ontogenetic experience and sex

“…Our previous work has revealed substantial habitat‐dependent population divergence in morphological, life history and behavioural traits between coastal marine and pond populations (Gonda et al. , 2009a,b; Herczeg et al. , 2009a,b,c, 2010a,b, 2011); all patterns suggesting that coastal marine populations are adapted to high predation (e.g.…”