The Evolution of a Female Genital Trait Widely Distributed in the Lepidoptera: Comparative Evidence for an Effect of Sexual Coevolution

Sexual coevolution is considered responsible for the evolution of many male genital traits, but its effect on female genital morphology is poorly understood. In many lepidopterans, females become temporarily unreceptive after mating and the length of this refractory period is inversely related to the amount of spermatophore remaining in their genital tracts. Sperm competition can select for males that delay female remating by transferring spermatophores with thick spermatophore envelopes that take more time to be broken. These envelopes could select for signa, sclerotized sharp structures located within the female genital tract, that are used for breaking spermatophores. Thus, this hypothesis predicts that thick spermatophore envelopes and signa evolve in polyandrous species, and that these adaptations are lost when monandry evolves subsequently. Here we test the expected associations between female mating pattern and presence/absence of signa, and review the scant information available on the thickness of spermatophore envelopes.We made a literature review and found information on female mating pattern (monandry/polyandry), presence/absence of signa and phylogenetic position for 37 taxa. We built a phylogenetic supertree for these taxa, mapped both traits on it, and tested for the predicted association by using Pagel's test for correlated evolution. We found that, as predicted by our hypothesis, monandry evolved eight times and in five of them signa were lost; preliminary evidence suggests that at least in two of the three exceptions males imposed monandry on females by means of specially thick spermatophore envelopes. Previously published data on six genera of Papilionidae is in agreement with the predicted associations between mating pattern and the characteristics of spermatophore envelopes and signa.Our results support the hypothesis that signa are a product of sexually antagonistic coevolution with spermatophore envelopes

Biology and conservation of Zerynthia cassandra (Lepidoptera, Papilionidae) in semi-natural environments and agricultural landscapes

The Southern festoon, Zerynthia polyxena, is a south-European butterfly listed in Annex IV of the Habitats Directive (92/43/EEC). Populations from most of the Italian territory have been recently recognized as belonging to a separate species, endemic to Italy: Zerynthia cassandra. In the province of Bologna (northern Italy), Z. cassandra is quite common. The territory of the province is densely inhabited and modified by man. Semi-natural environments are found almost exclusively in the hills, while the plain is almost entirely built-upon or cultivated. This study was based on data collected in the field in the province of Bologna, and aimed to investigate some biological and ecological aspects of Z. cassandra, with the purpose of identifying the factors that favour its presence and the most relevant issues for its conservation. In the area of study, the hostplant of Z. cassandra is Aristolochia rotunda, which is common in the plain, along the edges of drainage canals, where it supports a large Z. cassandra population. In the hills, A. rotunda is scarcer, and Z. cassandra is present in small separated nodes. Human activities such as mowing and canal maintenance are potentially damaging to Z. cassandra, particularly if carried out when eggs and larvae are present. However, if correctly timed and executed, such maintenance can preserve grassy areas that would otherwise be colonized by bushes and trees, and in which A. rotunda finds a suitable environment. Some level of disturbance can be beneficial for Z. cassandra habitats, favouring the species’ survival in the long term