Evol Ecol Res 7: 581-593 (2005) Full PDF if your library subscribes.
Sexual ornamentation and parasite infection in males of common bream (Abramis brama): a reflection of immunocompetence status or simple cost of reproduction?
Eva Ottová,1 Andrea Šimková,1* Pavel Jurajda,2 Martina Dávidová,1 Markéta Ondračková,1,2 Martina Pečínková1 and Milan Gelnar1
1Department of Zoology and Ecology, Faculty of Science, Masaryk University, Kotlářská 2, 61137 Brno and 2Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Květná 8, 60365 Brno, Czech Republic
Author to whom all correspondence should be addressed.
Question: How does sexual ornamentation relate to parasite infection, host immune response and somatic condition status in male fish?
Hypotheses: Zahavi’s (1975) handicap hypothesis proposes that producing secondary sexual traits represents a considerable handicap for males. Additionally, Hamilton and Zuk (1982) proposed that the expression of secondary sexual traits reveals a genetic resistance against parasites.
Organisms: Spawning males of common bream (Abramis brama) and several of its parasites (Gyrodactylus spp., Diplostomum spp., Argulus spp.).
Variables: Parasite abundance (for parasite infection), spleen size (for host immune response) and condition (for somatic condition status).
Results: The more tubercles on the fish, the more abundant the Gyrodactylus spp. The more tubercles on the fish’s head, the more abundant the Diplostomum spp. The greater the mean length of the head tubercles, the more abundant the Gyrodactylus spp. and Argulus spp. However, we found no relationship between spleen size and either sexual ornamentation or parasite infection. Fish with larger spleens were in poorer somatic condition, but condition was not related to male ornamentation or parasite abundance.
Conclusions: Males that develop more intensive sexual ornamentation are more susceptible to metazoan ectoparasite infection, supporting the hypothesis of Hamilton and Zuk. However, our results do not support the hypothesis that immunosuppression by steroid hormones reduces immunocompetence.
Keywords: cost of reproduction, fish, immunocompetence, parasitism, sexual ornamentation.
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