Extravagant ornaments of male threadfin rainbowfish (Iriatherina werneri) are not costly for swimming

Trappett, Andrew, Condon, Catriona H., White, Craig, Matthews, Phil and Wilson, Robbie S. (2013) Extravagant ornaments of male threadfin rainbowfish (Iriatherina werneri) are not costly for swimming. Functional Ecology, 27 4: 1034-1041. doi:10.1111/1365-2435.12097

Author Trappett, Andrew
Condon, Catriona H.
White, Craig
Matthews, Phil
Wilson, Robbie S.
Title Extravagant ornaments of male threadfin rainbowfish (Iriatherina werneri) are not costly for swimming
Formatted title
 Extravagant ornaments of male threadfin rainbowfish (Iriatherina werneri) are not costly for swimming
Journal name Functional Ecology   Check publisher's open access policy
ISSN 0269-8463
Publication date 2013-01-01
Sub-type Article (original research)
DOI 10.1111/1365-2435.12097
Open Access Status
Volume 27
Issue 4
Start page 1034
End page 1041
Total pages 8
Place of publication Oxford, United Kingdom
Publisher Wiley-Blackwell
Language eng
Abstract Exaggeration of male sexual ornaments should be costly, in terms of metabolic expenditure, resource allocation or even locomotor function. For example, many male ornaments are predicted to affect the aerodynamics, drag or biomechanics of movement and thus inhibit the speed or manoeuvrability of individuals; but empirical support for this is equivocal. We tested the locomotor and metabolic costs of exaggerated male ornaments in the threadfin rainbowfish (Iriatherina werneri), an Australasian native fish characterized by excessively long fin streamers. We predicted that males with greater relative ornamentation would have reduced escape abilities (i.e. burst swim speeds) as well as higher metabolic costs when resting or swimming. Furthermore, we evaluated the benefits of the signal by comparing the preference of females for males with differing amounts of ornamentation. As expected, we found that females spent more time observing (i.e. preferred) males with longer relative fins. We also experimentally reduced threadfin length and found that females continued to show preference for males with longer fins, rather than a preference for particular males. Male I. werneri with longer ornaments had higher resting metabolic rates, but we found no effect of ornament size on metabolic rates during swimming. Males with longer threadfins tended to swim faster, but our manipulation of fin length had no effect on burst swimming speed, indicating swimming abilities are not causally related to threadfin length. Overall, we found no evidence that the extravagant ornaments of male threadfin rainbowfish increase the metabolic or functional costs associated with swimming. Our results are surprising, given the high viscosity of water and the extreme length of I. werneri's ornaments. We suggest that future work should focus on the fitness costs of threadfin length, relative to reproductive output or survival under more natural conditions.
Keyword Compensatory traits
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Biological Sciences Publications
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