The viceroy (Limenitis archippus) is a North American butterfly. It was long thought to be a Batesian mimic of the monarch butterfly, but since the viceroy is also distasteful to predators, it is now considered a Müllerian mimic instead.

The viceroy was named the state butterfly of Kentucky in 1990.

Description

Its wings feature an orange and black pattern, and over most of its range it is a Müllerian mimic with the monarch butterfly (Danaus plexippus). The viceroy's wingspan is between . It can be distinguished from the monarch by its smaller size and the postmedian black line that runs across the veins on the hindwing. It has been possibly extirpated from California.

Adults are strictly diurnal, flying preferentially in the late morning and early afternoon. Adult viceroys nectar on milkweeds, thistles, and other common flowers. For butterflies to travel from the Palearctic region to the Nearctic region of the world, the migration must have occurred during a time period when Beringia, the land bridge between Eurasia and North America, was still above water. Based on crude divergence rate calculations, the colonization of the Nearctic Leminitis dates back approximately four million years. established itself in North America and resulted in several major lineages, three of which involved mimicry independently of each other. Given the present monophyly of the Nearctic species, it is likely that a single migration and subsequent expansion of the population was the foundation of the Nearctic butterflies.

Predators and avoidance

Color warnings in viceroy butterflies have been shaped by natural selection in an evolutionary relationship between prey and predator. The viceroy's main predators – like many other butterflies – consist mostly of birds.

Batesian mimicry

The viceroy's wing color ranges from tawny orange (resembling monarchs) in the north to dark mahogany (resembling queens) in the south. It has been argued that selective pressures from predators have given rise to "model switching" In addition, when given the choice between a mimic and non-mimic after being exposed to an unpalatable model, avian predators never ate the viceroy mimic.

left|upright=1.8<!--double image-->|thumb|Monarch (left) and viceroy (right) butterflies exhibiting [[Müllerian mimicry]]

The Müllerian mimicry dispute

Research has argued that the viceroy may be unpalatable to avian predators. If that is the case, then the viceroy butterfly displays Müllerian mimicry, and both viceroy and monarch are co-mimics of each other.

Some literature suggests that the queen-viceroy may not be a good model-mimic pair for Batesian mimicry. Experimental evidence has shown that avian predators express aversion to the queen butterfly after being exposed to viceroys. That the avian predators avoided the queen butterfly implies that the queen does not serve as a model and the viceroy as a parasitic mimic; rather, they may be Müllerian co-mimics. The drive behind this type of evolution must be predation. Eventually, the mimetic population undergoes phenotypic fixation, usually at a point where the wing pattern and colors of the mimic have reached the closest superficial resemblance of its model.

A fascinating feature of pattern genetics is that the dramatic phenotypic changes are primarily due to small changes in the gene that determines the sizes and positions of pattern elements. Different genomic rearrangements have tightened the genetic linkage between different color and pattern loci with complete suppression of recombination in experimental crosses in a 400,000 base section containing at least 18 genes.

References

Further reading

  • Glassberg, Jeffrey Butterflies through Binoculars, The West (2001)
  • Guppy, Crispin S. and Shepard, Jon H. Butterflies of British Columbia (2001)
  • James, David G. and Nunnallee, David Life Histories of Cascadia Butterflies (2011)
  • Pelham, Jonathan Catalogue of the Butterflies of the United States and Canada (2008)
  • Pyle, Robert Michael The Butterflies of Cascadia (2002)
  • Description of Viceroy on Butterflies and Moths website
  • viceroy butterfly on the UF / IFAS Featured Creatures Web site
  • Viceroy, Butterflies of Canada