Egg size plasticity corresponding to maternal food conditions in an annual fish, Ayu Plecoglossus altivelis

Abstract

The classic model of Smith and Fretwell predicts that the optimal egg size will vary according to the shape of the relationship between offspring size and offspring fitness, which may vary among environments. Adaptive significance of intrapopulation egg size variation was examined using Ayu (Plecoglossus altivelis). The species has an annual and migratory life history. Fish under controlled rearing conditions become sexually mature with a trend that smaller females produced larger eggs later in the season. Observed egg size variation was explained by the maternal specific growth rate, which was composed of maternal body size and growing period. Hatchlings from larger eggs had a larger notochord length, larger yolk-sac and grew faster. Such offspring traits provide general advantages of increased larval size, which confer competitive ability for assuring early survivorship. In conclusion, egg size plasticity in Ayu suggests higher offspring fitness through enhancement of their accessibility to food.

Loggerhead turtle (Caretta caretta) offspring size does not vary with maternal alternative foraging behaviors: support for their phenotypic plasticity

“…In some cases, prey quality or quantity is positively correlated with offspring size (Kaplan 1987;Warner and Lovern 2014), whereas, in other cases, it inversely affects offspring size (Reznick and Yang 1993;Jonsson et al 1996;Warner et al 2007;Iguchi 2012). Other works have shown a lack of correlation between prey and offspring size (Morita and Takashima 1998;da Costa Araújo et al 2013).…”

Stochastic optimal switching model for migrating population dynamics

“…The target species is the fish P. altivelis in Japan. Along with the present mathematical setting, the general life history of the fish in natural environment is briefly explained as follows (for more detail, see Iguchi [71] and Yoshioka and Yaegashi [70]). In autumn…”

“…The larvae grow up by feeding mainly on plankton in the sea until coming spring, at which mass migrations of the fish population from the sea to rivers occur. There exist several experimental and field findings on the ecology of the fish [69,[71][72][73]; however, much less attention has been made on modelling the entire life history of the fish. We hope that our methodology in the flavour of operations research, which is hence slightly different from the conventional ones, may open the door toward new mathematical modelling of animal population dynamics.…”