The Elements of Evolution (39-4) Sphinx Moths

 Sphinx Moths

Sphinx moths, also known as hawk moths, are a family of sizable moths with rapid, sustained flying ability. There are ~1,450 species of sphinx moths in ~200 genera.

Prosperpinus is a sphinx moth genus of 7 species. In general, these moths are green with red or orange hindwings. Like many other hawk moths, they hover like hummingbirds in front of the flowers from which they nip nectar. With 1 exception, Prosperpinus larvae feed exclusively on plants in the evening primrose family.

3 Prosperpinus species are unique in their own ways: the yellow-banded day sphinx, which lives in the boreal forests of North America; the Terloo sphinx, which is endemic to a region ranging from southern Arizona to Sonora in Mexico; and the Pacific green sphinx, which lives on the Pacific coast, from British Columbia to Mexico.

The yellow-banded day sphinx abandoned the green and red color scheme of its genus to make itself an excellent mimic of the bumblebees which share its forest habitat.

Terloo sphinx larvae feed only on spiderling plants, which are unrelated to the evening primrose plants that other Prosperpinus larvae dine upon. Spiderlings are favored because they are common during the mid-summer monsoon in the upland desert habitat where the moth resides and are in bloom during the few weeks when adults live.

Certain body parts of the Pacific green sphinx differ markedly from other Prosperpinus moths, so much so that it is was given its own monotypic genus: Arctonotus. That withstanding, it is the life history of the Pacific green sphinx that really sets it apart. Adult moths are active during early evening in mid-winter. Other Prosperpinus require heat and moisture to emerge from pupation. The Pacific green emerges when there are cold winter rains, where temperatures might fall below freezing.

There are virtually no blooming plants during the adulthood of the Pacific green sphinx. As a result, these moths don’t feed. They could not anyway, as their proboscis is nonfunctional. Adults rely wholly on energy acquired when they were larvae, more than 6 months prior.

Not only are Pacific green adult moths able to withstand frigid temperatures, but the eggs and larvae continue to develop during the winter, exposed to the bracing cold. This thermal robustness required unique cold-weather adaptations.

These 3 unique sphinx moth species independently speciated between 5.5 and 4.6 million years ago, in developments that are unrelated.

The rapid derivation of divergent unique traits, each in a separate species, strongly suggest that these adaptations are saltational. ~ Daniel Rubinoff & Johannes Le Roux