Physiological and condition-related traits in the gynogenetic-sexual Carassius auratus complex: different investments promoting the coexistence of two reproductive forms?

Abstract

BackgroundCarassius auratus complex is an extraordinary species complex including the diploid and polyploid forms exhibiting asexual and sexual reproduction modes. The coexistence of both forms in the same habitats is currently reported. The stable coexistence of asexual and sexual forms assumes some disadvantages for asexuals that balance the costs of sex. In our study, we hypothesized and tested the differences in physiological (including heamatological and immunological), growth-related, condition-related, and fitness-related traits between gynogenetic females and sexuals.ResultsOur results revealed similar growth performance in gynogenetic females and sexuals measured by body size and weight, or expressed by condition factor. The energy allocation in reproduction measured by the relative size of gonads revealed no difference between gynogenetic and sexual females; in addition, both females in spawning expressed the same estradiol levels in blood plasma. We found a gender specific trade-off between investment in reproduction and immunocompetence (measured by the spleen-somatic index). Higher aerobic performance expressed by the heart index and higher oxygen-carrying capacity were found in sexual males, with increasing values before and during spawning. Our study evidenced significantly lower aerobic performance but higher oxygen-carrying capacity per erythrocyte in gynogenetic females when compared to sexuals. IgM production differed between gynogens and sexuals of C. auratus complex.ConclusionsOur study indicates that a similar amount of energy is invested by both gynogenetic and sexual females of C. auratus complex in reproductive behaviour. We suggest that lower aerobic performance in gynogens may represent their physiological disadvantage balancing the cost of sexual reproduction. A trade-off between the number of erythrocytes and the oxygen-carrying capacity per erythrocyte in sexual males and gynogenetic females may contribute to the coexistence of gynogenetic and sexual forms. In addition, the differences in specific immunity between gynogens and sexuals may also reduce the evolutionary disadvantage of sexual reproduction. In conclusion, we propose that several mechanisms contribute to the coexistence of the gynogenetic-sexual C. auratus complex.

Morphologically indistinguishable hybrid Carassius female with 156 chromosomes: A threat for the threatened crucian carp, C. carassius, L

“…carassius in Europe; and (ii) whether the Carassius cryptic diversity represents a threat for native species. The asexual gynogenetic mode of reproduction supposedly prevails in polyploid Carassius hybrids and forms clonal lineages [ 67 ]. Gynogenetic reproduction gives rise to a higher number of progeny than sexual reproduction [ 31 ] because asexual gynogens are usually not limited by the searching for a sexual partner, and they generate almost all female populations [ 68 ].…”

A Long Temporal Study of Parasitism in Asexual-Sexual Populations of Carassius gibelio: Does the Parasite Infection Support Coevolutionary Red Queen Dynamics?

“…They applied the genotyping of major histocompatibility complex (MHC) IIB genes and showed that the most common MHC genotype of the gynogenetic form is more parasitized than sexual genotypes or rare gynogenetic genotypes. In addition, Šimková et al [ 29 ] hypothesized that the different investments in condition-, growth-, and fitness-related traits may represent other mechanisms contributing to the coexistence of gynogenetic and sexual forms of the C. auratus complex. However, they revealed similar growth, expressed in terms of body size, and similar condition factors in gynogenetic and sexual forms and failed to identify the reproductive disadvantage for the gynogenetic form when investment in reproduction was measured by gonad weight and estradiol level.…”

“…This indicates that similar energy is invested in the reproduction of gynogenetic and sexual females. In addition, Šimková et al [ 29 ] proposed the existence of a new mechanism potentially contributing to the coexistence of gynogenetic and sexual forms of the C. auratus complex, that is, the low aerobic performance in gynogens, which may represent a physiological disadvantage balancing the evolutionary cost of sexual reproduction. In addition, Vetešník et al [ 30 ] identified higher concentrations of triacylglycerols and cholesterol in the blood plasma of gynogenetic females, indicating a higher metabolic rate and higher energy intake when compared to sexuals.…”

Capacity of blood plasma is higher in birds breeding in radioactively contaminated areas

“…Different immune components are not necessarily positively related to each other [41]. Although negative associations are consistent with a trade-off between different components of immunity [42], other studies detected positive or no associations among different lines of immunity [43]. Moreover, immunity is also related to a variety of physiological characteristics such as growth, reproduction and survival that depend on environmental factors and seasonality [44], which may have changed during the last 30 years.…”