Abstract

Egg mimics in Etheostoma (Catonotus) oophylax appear before the beginning of the breeding season and reach maximum size in the middle of the season when most spawning activity is expected. Mimic length, but not width, increases with male body size. Males of this species display laterally to females, and, as expected if the trait is subjected to female choice, the lateral dimension of the mimic is the largest. Egg mimics varied from 0.5 to 1.8 mm in length, potentially providing a wide choice for females. Eggs of E. oophylax average 2.2 mm in diameter, which is 22% larger than the largest mimics. If female choice of males or nest sites is determined by how effectively males mimic eggs, or how conspicuous mimics are, large males and males holding territories in the middle of the breeding season when mimics are largest have the advantage. If mimic size is important, choice of resources, that is, presence or absence of eggs in the nest site, may be more important to females than choice of male.