To say this species of fungus is attractive is an understatement. It is simply stunning to look at! This medium sized mushroom is highly regarded in its native New Zealand, where it grows in forest habitats. Although most Entomolaspecies break down dead organic material, Entoloma hochstetteri is thought to engage in mycorrhizal relationships with Nothofagus and Podocarpus tree species. As soon as I first laid eyes on this mushroom, I knew I had another bucket list entry to write down. Looking at my list, I realized that New Zealand is becoming a prime fungal destination for me. There is a wide variety of bright colored species endemic to the region. I think it’s a bit funny that I’m drawn to the furthest place away from me at my current global position. Though, it does makes perfect sense, because it is these species that I have the least chance of encountering. There is a special allure to the isolated region, and I promise that someday I’ll be writing posts about my first-hand experiences scouring the forest floor in some New Zealand ecosystem. Today, Entoloma hochstetteri embodies that excitement and yearn for knowledge; the ongoing quest to better understand this planet’s ecosystems from the bottom up.
It really is no surprise that Entoloma hochstetteri has found its way to New Zealand’s fifty-dollar bill. Just taking a look at New Zealand’s other bank notes, you will find that several birds, insects, plants and natural forest and mountain landscapes have become celebrated symbols of the county. This shows that many people living here treasure their natural habitat and understand the ecological services they provide. I think it’s time more countries adopt these types of illustrations of on their currency, especially if its fungi.
Some of you might be rolling your eyes at this post, as yet again I selected another bright colored forest floor inhabitant. I know, there are significantly more non-vibrant species and aesthetics to humans should be irrelevant when it comes to learning about different species. But I am only human, and I really like these bright colored exotic species. Besides this predictable appreciation for pretty mushrooms, there is an evolutionary talking point here. That talking point is actually this species aesthetically pleasing color.
Blue is an uncommon color to find in terrestrial habitats. Blue color is found in some butterflies and birds, but as of right now, only one animal species we know of produces blue pigment. Nessaea aglaura is a butterfly that has evolved a blue pigment in its wings. Any other time you see blue on an animal, you can be sure it is not a pigment, but actually the structure of the surface. In these blue surfaces, some of wavelengths of light are canceled out by just the way the microscopic structures are positioned. It has been hypothesized that along the evolutionary trajectory of terrestrial species, eyes became sophisticated enough to see blue. Instead of relying on chemistry, (the synthesis of new pigments) many non-related species started producing blues through engineering. From an evolutionary standpoint, changing the structure of a surface can occur much faster than creating new blue pigments. Species with a faster path to producing blue have increased fitness as they were the first to access this new color niche. This brings us back to our blue mushroom featured in today’s Fungi Friday.
Unlike the rest of blue terrestrial species, Entoloma hochstetteri does produce pigments. Actually, E. hochstetteri produces three azulene pigments that gives it its vivid blue coloration. Azulene is an organic molecule which is also found in other non-related fungal species. Lactarius indigois a more widespread species that too produces versions of azulene. This begs the question as to why these mushrooms produce a blue pigment. Well, there’s really no evolutionary rush to produce blue pigments for the sake of the blue coloration in mushrooms. In animals, sexual selection is a ginormous aspect of an individual’s fitness, so faster paths to blue coloration have occurred. Once a species ‘figures out’ how to be blue, there’s no selection pressure to change these structural mechanisms to chemical ones. In fungi, there is no sexual selection, so randomly colored pigments evolve overtime. These pigments are going to have some other functions attributed to them besides just unique coloration. Unless if the fungus is dispersed by an animal with good vision, coloration is largely unimportant to the species survival. The azulene pigments have been proposed to have antiherbivore properties, allowing more mature individuals to release spores without being devoured by fungivorous insects.
Nature is just so humbling. There are so many complex interactions taking place over really small-time scales as well as over millennia. By looking at the occurrence of the color blue in different species, we can build several evolutionary intricacies. Blue is a notoriously more difficult pigment to evolve, which has led to animal species coming up with structural solutions instead of chemical ones. Since fungi don’t see, and usually don’t use animal dispersers that specialize in seeing blue, blue pigments have slowly evolved. These pigments most likely have other ecological functions and appear blue just by chance. Regardless of all this evolution and ecology talk, Entoloma hochstetteri is an awesome species, and has the power to attract aspiring mycologists to opposite sides of the planet. I really wish the United States used more native species on its currency. What mushroom do you think is worthy making it on a U.S. hundred-dollar bill?