Butterfly populations are a very good indicator of the health of an area's ecosystem !!
Blue Morphos, Blue Waves and other seemingly blue colored butterflies actually have no blue pigmentation in their bodies. (The blue coloration that you see is structural coloration, rather than pigmentation.) (Blue pigmentation is extremely rare in animals.)
Butterflies can show bright blue, green, red, purple or grey/white wings due to structural colors that are created by photonic cells rather than by colored pigmentation in the body.
Colored pigments work the way you would probably expect.
Similar to the pigments in crayons or colored pencils, the molecules themselves have a certain color. (They absorb most colors of light but reflect others, and we perceive the reflected light as color.)
Blues come from structural pigments.
The molecules themselves are black, not blue, but their shape at the microscopic level causes them to reflect blue light. (This gives them their iridescent or metallic quality.) Depending on the angle and intensity of light, they will look either black or bright blue. White is another structural color in butterflies. Usually it comes from microscopic air bubbles that reflect light. (Structural color is also very common in bird feathers.)
All these pigments and structures are built by proteins. Groups of proteins work together to turn raw materials into richly colored molecules.
(The instructions for making the proteins are coded in genes. Differences in genes can cause differences in proteins.These differences can affect the qualities of a pigment that the protein helps to build, like its color or intensity.)
Butterfly Pigment Types
Melanin - creates grays, browns and blacks and helps butterflies absorb heat from sunlight.
Ommachrome - creates reds, oranges, tans. These pigments are common in insects. Besides butterflies, they usually color eyes.
Papiliochrome - creates yellows and cremes. Some of these pigments also make patterns in the ultraviolet light range. (These patterns are visible to butterflies but not to humans.)
Pterin - creates orange colorations. (Butterflies in the Pierid family use these pigments, rather than ommachromes, to create oranges.)
Genes & Effects
Optix - is known for producing large spots of colors and long, thin ray patterns. This gene works like a control switch to affect multiple pigment production pathways at once. In places where optix is active, ommachrome (red, orange, and tan) production is switched on and melanin production (black and grey) is switched off. In some species, optix is also involved in structural blue color, which is built from black melanin pigments.
Cortex - affects black pigment patterns in some species, and white and yellow in others. It may work by affecting how quickly the cells that make scales mature. (Black scales usually mature more slowly than others.)
Aristaless - affects switching between yellow and white patterns. It often produces bands on the forewings and hindwings, or spots on the bottom edge of the hindwing.
WntA - fine tunes the size and shape of spots and stripes that are laid down by optix and cortex.
Many butterfly species are known for their spectacular eyespots. These colorful "eyes" can scare predators and / or draw their attention away from vital organs. Two genes, spalt and distalless, are active in the centers of many eyespots.
Other butterfly families use different sets of control genes, but in similar ways.
Genes like the ones described here allow for great flexibility and rapid shifts within species. In order for its patterns to shift, a species doesn’t need completely new color building or pattern making genes.
(Small changes to existing genes can make new patterns with nearly endless variations!!)
