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

Tomáš Pakosta,Andrea Šimková,Lukáš Vetešník

doi:10.1155/2018/6983740

Abstract

Carassius gibelio is an extraordinary cyprinid species exhibiting both sexual and asexual reproduction. We hypothesized that parasitism selection is one of the potential mechanisms contributing to the coexistence of the two reproductive forms of C. gibelio living in the same habitat. We performed a four-year study to investigate the dynamics of parasite infection in C. gibelio. According to the Red Queen prediction, the asexual form is a target of parasite adaptation due to its low genetic variability. Both sexual and gynogenetic forms of C. gibelio exhibited similar levels of prevalence, with monogeneans being the most frequently observed parasite group. We observed the temporal dynamics of parasite infection in the last year of investigation, when both forms were more strongly parasitized. The sexual form was more parasitized by ectoparasites in the first and last years and less parasitized by nematodes in the last year when compared to the gynogenetic form. We found no trend of high parasite infection in gynogenetic mtDNA haplotypes. We conclude that Red Queen dynamics is not the mechanism driving parasite infection in sexual-gynogenetic C. gibelio over a long time scale. Alternatively, we suggest that the dynamics of parasite infection in this complex may be generated by multiple mechanisms.

Highlights

The coexistence of sexual and asexual forms is rarely reported in vertebrates
In the context of asexual reproduction, gynogenesis has a specific constraint as the sperm of males are necessary to induce embryogenesis; that is, the eggs of gynogenetic females are stimulated by sperm of usually conspecific males to start embryogenesis but the sperm do not fuse with the egg nucleus
In the present long-term study, we investigated the compositions of parasite communities and levels of parasite infection in coexisting gynogenetic and sexual forms of the cyprinid C. gibelio, representing the most common form of the C. auratus complex in the Czech Republic

Summary

Introduction

The coexistence of sexual and asexual forms is rarely reported in vertebrates. The stable coexistence of these two forms may be achieved if there are some disadvantages for asexuals compensating the evolutionary twofold costs of sexual reproduction [1, 2]. In the context of asexual reproduction, gynogenesis has a specific constraint as the sperm of males are necessary to induce embryogenesis; that is, the eggs of gynogenetic females are stimulated by sperm of usually conspecific (or, alternatively, phylogenetically closely related) males to start embryogenesis but the sperm do not fuse with the egg nucleus. In such case, the asexual and sexual forms are forced to coexist as the persistence of the sexual form is in the direct interest of the gynogenetic form. This means that gynogenetic form (which may be considered as a “parasite” using the sperm of sexual males) cannot outcompete the sexual form (which may be considered as “host” for gynogenetic form)

Methods

Results

Discussion

Conclusion