Systematics, Evolutionary Biology and Population Genetics of the Cercyonis pegala Group (Lepidoptera: Nymphalidae: Satyrinae).

A. Sourakov

Abstract


This study is an overview of the systematics of the Cercyonis pegala group of butterflies. Laboratory cultures of three different subspecies were established in the summer of 1993. Interbreeding experiments between different subspecies of Cercyonis pegala from Ohio and Colorado were conducted successfully. Breeding of color morphs in the highly variable population from Ohio proved the "form" status of the yellow-banded (C. p. alope) and dark-brown (C. p. nephele) specimens, instead of subspecific or specific status. Studies of over 5,000 specimens of Cercyonis pegala in the major entomological collections, led to the conclusion that Eastern U.S. populations of C. pegala have clinal status rather than being separate subspecies. A new treatment is proposed which synonomizes all names of subspecies in the East. The present condition of the systematics of C. pegala across the Western United States is discussed, however, the existing extensive use of subspecific designations there is not altered due to insufficient biological and genetic information. This study also attempted to apply analyses of different populations for cuticular hydrocarbons (by gas chromatography) and for genetic variation in genes controlling a number of enzyme systems (via allozyme electrophoresis) for obtaining additional information on the organisms. However, these techniques proved to be not capable of resolving useful variation or differentiating populations or taxa at the subspecific level. Studies of the immature stages of different subspecies of C. pegala were also conducted, and these findings led to the conclusion that there are extreme similarities in egg, larval, and pupal characters on the subspecific level in this group. All taxonomically useful characters that have been used to define forms or subspecies in this butterfly complex therefore are confined to the adult stage. Studies on larval biology and mating habits of Cercyonis pegala showed that mating is restricted to different hours in the day for different populations, even when all are bred under similar conditions. Also, significant differences were shown in the behavior of larvae of different subspecies. Finally, change in daylength was found to be a significant, if not the only factor involved in breaking the larval diapause, eliminating the usual concept of temperature being the key factor in this process.

Keywords


Acari; allozymes; behavior; biogeography; Canada; Cercyonis; diapause; Diptera; distribution; eggs; electrophoresis; evolution; gas chromatography; genetics; Great Basin; hydrocarbons; Hymenoptera; Hyponephile; larval biology; Maniola; Maniolini; Mexico; Minois; Nearctic; North America; Nymphalidae; Orthoptera; pupae.

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