Al. Basolo, EVOLUTIONARY CHANGE IN A RECEIVER BIAS - A COMPARISON OF FEMALE PREFERENCE FUNCTIONS, Proceedings - Royal Society. Biological Sciences, 265(1411), 1998, pp. 2223-2228
Female poeciliid fishes of the sister genera Xiphophorus and Priapella
share a preference for males with swords, despite phylogenetic inform
ation suggesting that swords arose in Xiphophorus after the divergence
of the two genera. This study examines the strength of sword and body
-size preferences in a representative of both genera. A comparison of
the preference functions reveals that the strength of the preference f
avouring a sword in P. olmecae is significantly stronger than that in
X. helleri. This result demonstrates that the pre-existing bias is not
evolutionarily fixed, and that there has been change in the bias favo
uring the sword, in either the Priapella lineage, or the Xiphophorus l
ineage, or in both. Although females in both species prefer conspecifi
c males with swords, only;PI. helleri females also demonstrate a body-
size preference. The preference functions for body size and sword leng
th for X. helleri are not significantly different, whereas in P. olmec
ae the preference function for sword length is significantly stronger
than for body size. These combined results indicate that an ancestral
bias for body size cannot alone explain the pre-existing bias favourin
g a sword in P. olmecae.