title: Why do males emerge before females? : A hypothesis to explain the incidence of protandry in butterflies.
abstract: In butterflies and many other insects there is a general tendency for males to emerge before females. This is known as protandry. In this paper we advance the hypothesis that protandry is a reproductive strategy of males, resulting from competition for mates, and should primarily occur in species maintaining female monogamy. Our hypothesis is corroborated by applying a mathematical treatment to a theoretical population with seven defined properties, all of which are argued to be reasonable assumptions for natural populations.
authors.affiliation: Department of Zoology, University of Stockholm, Box 6801, S-113 86, Stockholm, Sweden.
authors.forename: Christer
authors.initials: C
authors.lastname: Wiklund
authors.affiliation: Swedish Coniferous Forest Project, Box 7042, S-750 07, Uppsala, Sweden.
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Fagerström