Monarch Predators Have Also Evolved to Withstand Toxic Milkweeds

Monarch butterflies are famous for their beautiful colors and their long migration patterns. They are also well known for being poisonous due to their consumption of the milkweed plant. A genetic mutation found in monarchs block the plant’s toxins while also allowing said toxic to accumulate in the insect. This mutation is found in 3 copies of a gene for the sodium-potassium pump and is critical to the monarch’s ability to tolerate the toxins of the milkweed found a group of researchers two years ago. This mutation, along with the monarch’s warning color has helped as a deterrent to hungry predators.

However, monarchs are not the only species that can tolerate the milkweed’s toxins. This article shows that four different predators of monarchs were recently discovered to have the same genetic mutation that monarchs have. These organisms are the black-headed grosbeak, the eastern deer mouse, a tiny wasp that parasitizes monarch eggs, and a nematode that parasitizes monarch larvae. All four organisms have at least one or more copies of the gene. The black-headed grosbeak and wasp has evolved single-nucleotide mutations in their sodium pump gene in two of the three locations where monarchs evolved the mutation. The eastern deer mouse and nematode have their changes in all three locations. Noah Whiteman, evolutionary biologist and member of the study, noted that this might be the first time we are seeing the same resistance mutations that have been found in the second and third trophic levels that evolved due to the second trophic level’s ability to feed on toxic plants. The team suspects that there are other organism in the food chain that begins with the milkweed that also have the same mutations found in monarchs.

One gene has a large effect on Monarch Butterflies

Each and every year, one of the most iconic insects in the world, the monarch butterfly, usually migrates across North America. However, a group of researchers from the University of Chicago Medical Center, have been sequencing genomes from these distinctive orange and black winged butterfly and found a single gene that is involved with migration. In order to find the one single gene, the researchers compared the genomes of migratory butterflies against three types of non-migratory populations. They were able to find over five hundred genes that are involved with muscle and also developmental and neural function. The gene that different between the migratory and non-migratory butterflies was collagen IV α-1. It was the migratory butterflies that had a reduced level of this gene, the researchers discovered that these butterflies consumed less oxygen and had lower metabolic rates when flying that gives them the ability to fly long distances.

White and Black Monarch

Orange and Black Monarch

Apart from researching the monarch butterflies to figure out how certain butterflies migrate and others do not, the researchers also investigated the monarchs coloration. As I stated earlier, most monarchs do have orange and black wings, but a small percentage of them that are mostly located in Hawaii, have white and black wings. They are sometimes known as the Hawaiian Monarch. When conducting their research, they found that once again, a single gene has a drastic effect of the pigmentation of the monarchs. This gene codes for a protein that is of the myosin motor protein family, and it has never been implicated to the coloration of insects. The mutation in this gene for monarchs disrupts the pigment transportation to the wings, is closely related to the myosin 5a gene in mice that affects the coat color of mice.

I was interested in this article because butterflies have always intrigued me and through this article, I gained a lot of knowledge that I did not know previously. I never knew that one single gene could change a species so much and I also did not know that all monarch butterflies do not migrate during the winter. The results of the study conducted by the researchers showed a need to conserve the efforts to preserve the migrating monarchs and extend the extraordinary evolutionary history of the species as well.

Article: Genetic secrets of the monarch butterfly revealed

Related Articles: How One Gene Gives Monarch Butterflies the Power to Migrate

A Single Gene Affects a Butterfly's Ability to Migrate

Everyone knows about the monarch butterfly and most of us believed that it migrates south every year when it gets colder - but not every monarch butterfly migrates.  A study of butterflies, including 92 monarch butterflies, has shown that only some are migratory - the others were non-migratory.  In the study, there was a correlation between a single gene called Collagen IV alpha-1 and a monarch's ability to migrate.  Research shows that this gene affects the muscle building component and metabolism of a monarch butterfly, therefore affecting its ability to fly long distances.  When the monarchs are not migrating, there is no observed difference between those that have the gene and those that don't.

In addition to researching Collagen IV alpha-1, scientists studied the genome of migratory monarchs and determined that they did not originate in South America, but originated in North America or Mexico 1 to 2 million years ago.  The population began to grow about 20,000 years ago after the Last Glacial Maximum when milkweed became more readily available for consumption.

Lastly, researchers looked into the genes behind the orange and black coloring of the monarch butterfly.  When comparing a normal looking monarch butterfly to the black and white variety found in Hawaii, a gene called DPOGS206617 had a strong correlation with wing coloration.  This gene is similar to the one found in mice that gives their coats coloration.

This article initially caught my interest simply because the monarch butterfly brought back memories of my first grade class when we raised monarchs from the time they were caterpillars until they grew into butterflies.  I was intrigued when I read that not all monarch butterflies are migratory - I thought that all monarchs migrated!  It was interesting to learn that this is caused most likely by a single gene.

Monarch Butterfly Genome Sequenced

Monarch butterflies have long been a fascination to scientists for their remarkable migration. Each fall, successive generations of these delicate creatures are able to traverse thousands of miles to find a tiny region only about 300 square miles in size. Each monarch that makes the long journey is at least two generations removed from their predecessors who had made the journey the year before. This phenomenon has mystified scientists for ages. With no relatives on the journey to lead the way and no previous knowledge of the specific overwintering site, monarch butterflies must harbor some genetic program that allows for this migration to occur year after year. That is why the paper published recently in the journal Cell describing the findings and observations from completely sequencing the monarch butterfly's genome was so interesting. The researchers identified genes involved with using the "sun compass," odor receptors that are potentially vital to long-distance migration, and much more.