Additional Hybridization Studies of Genomic Compatibility and Phenotypic Expression in the Genus Speyeria (Nymphalidae: Argynnini)

Abstract

The genetic compatibility of the most divergent species within the genus Speyeria was tested in 25 different hybrid crosses and back-crosses. In addition, the inheritance and expression of various phenotypic characters of wing pattern and coloration were studied including examples of extreme sexual dimorphism in certain species. These characters are important for the taxonomic diagnosis and identification of the various Speyeria taxa. Most of these characters or traits appear to have a complex polygenic inheritance with more continuous ranges of variation that have often become fixated at one end of the continuum for many taxa. However, other characters show a simpler Mendelian inheritance of dominant or recessive expressions. Some color pattern traits appear to be unique for one or two species, but most characters appear to be widely shared among many different Speyeria taxa. The results of these hybrid crosses suggest that extensive interspecies gene flow through natural hybridization may have been important in shaping the past evolutionary history of this genus. Also, the extensive clinal intergradation between highly divergent eastern and western subspecies of S. atlantis is documented in northwestern Minnesota.