Field bioassays show heterospecific mating preference asymmetry between hybridizing North American Papilio butterfly species (Lepidoptera: Papilionidae)

Abstract

Few studies of interspecific mating preferences of naturally hybridizing species have been done in the field. Yet this is the only way potentially critical habitat-specific factors can be included in mating behavior evaluations. We conducted mate selection (male preference) studies using tethered pairs of heterospecific, size-matched virgin yellow females of Papilio glaucus and P. canadensis with free-flying male P. glaucus populations in south-central Florida, and with free-flying male P. canadensis populations in northern Michigan. Florida males clearly preferred the conspecific P. glaucus females of the pairs, as indicated by the touches/ attempted matings and by the actual copulations observed. In 1997, 66.7% of the total attempts ( n = 168) and 94.2% of all copulations ( n = 69) were with the conspecific. In 1998 the same pattern of conspecific male preference was observed, with 67.3% of the touches/attempts ( n = 49) and 100% of the copulations ( n = 30) being with the P. glaucus females. In contrast, the natural populations of P. canadensis males did not show the expected conspecific preference. In fact, with wild P. canadensis males in 1997 a very strong preference was observed for the heterospecific P. glaucus females of the pairs, accounting for 75.8% of all touches/attempted matings ( n = 483) and 81.7% of all copulations ( n = 476). The strong asymmetry in interspecific mating preferences among these hybridizing Papilio species may reflect an ancestral trait in P. glaucus females that elicits strong preference in P. canadensis males, due perhaps to previously possessed male sensory bias or "good genes" indicators in the females. However, reinforcement of reproductive isolation in or near the hybrid zone of species overlap (sympatry) cannot be ruled out.

Sex Chromosome Mosaicism and Hybrid Speciation among Tiger Swallowtail Butterflies

“…The changing thermal landscape likely brought the advancing glaucus populations into contact with a relict canadensis population in the Appalachian Mountains. The ensuing hybridization seems to have been largely unidirectional, with canadensis males preferentially mating with glaucus females, as they do today [12]. Hence, appalachiensis is now fixed for the glaucus mitochondrial genome, along with its W-linked female-limited mimicry and dimorphism.…”

Allochronic Separation versus Mate Choice: Nonrandom Patterns of Mating between Fall Armyworm Host Strains

“…However, laboratory evaluations of individual reproductive barriers may severely underestimate the total reproductive isolation achieved in nature. The natural environment may affect mating preferences in manifold ways (Deering and Scriber 2002), and several layers of pre-and postzygotic isolation mechanisms can act simultaneously or successively (e.g., Groot et al 2010). When several different barriers exist at sequential stages of the life history, their relative contributions can be calculated, assuming that they contribute multiplicatively to the total reproductive isolation (Ramsey et al 2003).…”

Recent Speciation in Three Closely Related Sympatric Specialists: Inferences Using Multi-Locus Sequence, Post-Mating Isolation and Endosymbiont Data

“…The parental species of Papilio are also not isolated by pre-mating mate-preference barriers [69] nor by post-mating egg viability. In other Lepidoptera, there are combinations of reproductive isolating factors other than reduced egg viability.…”