Efforts in the development of Trojan sex chromosome carrying Red Shiner (Cyprinella lutrensis) and Green Sunfish (Lepomis cyanellus) for the control of nuisance populations in the Southwest

Authors: Chad Teal, Daniel Schill, D. Coykendall, Matthew Campbell, Susan Fogelson, Daniel Eardley, Thomas Delomas, Colby Roberts, Melanie Culver, Kevin Fitzsimmons, Scott Bonar

Year: 2021

Abstract

Red Shiner Cyprinella lutrensis and Green Sunfish Lepomis cyanellus are considered highly invasive when introduced outside of their native range. Trojan sex chromosome eradication models have shown the release of YY males (or ZZ females) to be effective at suppressing and eradicating invasive populations of species across genera. Developing Trojan sex chromosome carrying individuals requires aquaculture protocols, knowledge about gonadal development, identification of sex determination systems, and sex reversal methods for the species of interest. We have developed aquaculture protocols for Red Shiner and Green Sunfish. Red Shiner’s gonadal differentiation was observed between 45 days post hatch (dph) - 105 dph. Green Sunfish’s gonadal differentiation was observed between 39 dph - 69 dph. We observed 100% feminization of Red Shiner fed 100 mg Estradiol-17? (E2) kg^(-1) of diet from 20 dph - 120 dph. We observed 100% feminization of Green Sunfish fed 100 mg E2 kg^(-1) of diet from 30 dph - 90 dph. Using restriction-site associated DNA sequencing we developed a single nucleotide polymorphic sex identification marker that is heterozygous in male Red Shiner. This sex identification marker was 95.74% (45/47) accurate at identifying phenotypic sex in unrelated Red Shiner individuals, thus providing evidence of a female-XX/male-XY sex determination system in this species. All developed and tested sex identification markers for Green Sunfish were unreliable as an identifier of phenotypic sex. It is possible that the sex determination system in Green Sunfish is polygenic and there maybe environmental effects on sexual differentiation in this species. Our results are useful for assessing the potential use of a Trojan sex chromosome eradication strategy to control nuisance populations of Red Shiner and Green Sunfish.