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Demasculinization of male guppies increases resistance to a common and harmful ectoparasite

Dargent, F, Reddon, AR, Swaney, WT, Fussman, GF, Reader, SM, Scott, ME and Forbes, MR (2015) Demasculinization of male guppies increases resistance to a common and harmful ectoparasite. Parasitology. pp. 1-9. ISSN 1469-8161

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Parasites are detrimental to host fitness and therefore should strongly select for host defence mechanisms. Yet, hosts vary considerably in their observed parasite loads. One notable source of inter-individual variation in parasitism is host sex. Such variation could be caused by the immunomodulatory effects of gonadal steroids. Here we assess the influence of gonadal steroids on the ability of guppies (Poecilia reticulata) to defend themselves against a common and deleterious parasite (Gyrodactylus turnbulli). Adult male guppies underwent 31 days of artificial demasculinization with the androgen receptor-antagonist flutamide, or feminization with a combination of flutamide and the synthetic oestrogen 17 β-estradiol, and their parasite loads were compared over time to untreated males and females. Both demasculinized and feminized male guppies had lower G. turnbulli loads than the untreated males and females, but this effect appeared to be mainly the result of demasculinization, with feminization having no additional measurable effect. Furthermore, demasculinized males, feminized males and untreated females all suffered lower Gyrodactylus-induced mortality than untreated males. Together, these results suggest that androgens reduce the ability of guppies to control parasite loads, and modulate resistance to and survival from infection. We discuss the relevance of these findings for understanding constraints on the evolution of resistance in guppies and other vertebrates.

Item Type: Article
Additional Information: Copyright 2015 Cambridge University Press
Uncontrolled Keywords: 0707 Veterinary Sciences
Subjects: Q Science > QH Natural history
Q Science > QL Zoology
Divisions: Natural Sciences & Psychology (closed 31 Aug 19)
Publisher: Cambridge University Press (CUP): STM Journals
Date Deposited: 19 Oct 2015 10:15
Last Modified: 04 Sep 2021 13:53
DOI or ID number: 10.1017/S0031182015001286
URI: https://researchonline.ljmu.ac.uk/id/eprint/2196
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