Opercular flaps as sexual ornaments for male longear sunfish (Lepomis megalotis): Male condition and male-male competition

Citation
K. Goddard et A. Mathis, Opercular flaps as sexual ornaments for male longear sunfish (Lepomis megalotis): Male condition and male-male competition, ETHOLOGY, 106(7), 2000, pp. 631-643
Citations number
35
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Animal Sciences","Neurosciences & Behavoir
Journal title
ETHOLOGY
ISSN journal
0179-1613 → ACNP
Volume
106
Issue
7
Year of publication
2000
Pages
631 - 643
Database
ISI
SICI code
0179-1613(200007)106:7<631:OFASOF>2.0.ZU;2-S
Abstract
Male longear sunfish, Lepomis megalotis, have longer opercular flaps than f emales, and females are known to prefer males with longer flaps, suggesting that these exaggerated structures serve as sexual ornaments. We tested the hypothesis that opercular flap length is associated with body condition an d is therefore potentially an honest indicator of male quality. Opercular f laps grew significantly faster than pelvic fin spines, a non-sexually selec ted trait, regardless of diet treatment, suggesting an advantage to having fast-growing opercular flaps. Growth indices (opercular flap growth divided by pelvic fin spine growth) of males fed a larger ration were greater than those of males fed a smaller ration, although the difference was marginall y non-significant. We also tested for an effect of opercular flap length on resource holding power by manipulating flap length on pairs of males match ed for body length. In an experiment where opercular flaps were clipped to different lengths, only longer original (unmanipulated) flap length was ass ociated with a significantly greater frequency of dominance. In a corollary experiment where opercular flaps were artificially lengthened, the abnorma lly long-flapped males were dominant significantly more often than the 'nor mal' males given transparent extensions. These results indicate that the op ercular flap length of male longear sunfish may serve as an honest indicato r of male quality and may be used to assess the resource holding power of r ival males.