Story by Peter von Buol | Photography by Robert Lucking, Ph.D.
Seventy million years ago, the first Hawaiian Islands emerged from the Pacific Ocean. Then as now, Hawai‘i was the world’s most isolated archipelago. For the earliest life forms to arrive and gain a foothold as the lava cooled, it had to have been a remarkable journey.
Those first living things were probably tiny spores that drifted down from high in the atmosphere and set into motion the process that transformed a lifeless landscape into a lush island ecosystem.
Neither plant nor animal, the first Hawaiian may have been a species of lichen.
“There are approximately 2,000 species of lichens in Hawai‘i,” says Robert Lucking, a lichenologist at Chicago’s Field Museum of Natural History, home to one of the largest research collections of lichens in the world. “Of these, about 1,200 are found nowhere else.”
That so many lichens are endemic to the Islands wasn’t known until Lucking and his team started sequencing the DNA about a year ago.
Although they have done fieldwork all over the world, Lucking and his colleagues are paying special attention to Hawai‘i and other islands in the Pacific because they are Earth’s unique evolutionary laboratories. “Even more than the Galapagos Islands, in Hawai‘i we have been able to observe evolution on the spot.”
Lichens are symbiotic organisms that form when a fungus combines with an alga or cyanobacterium (also known as a photobiont), the photosynthesizing partner of the pair. It’s the fungus’s job to provide a nurturing environment for the photobiont to grow in. The photobiont returns the favor by transforming sunlight into carbohydrates for the fungus. Together, they are able to live in environments that, apart, neither fungus nor alga would survive.
Over hundreds of millions of years, lichens have evolved an astounding array of shapes, sizes and colors. Some bear a superficial resemblance to coral; others live on rocks and look like ‘opihi (limpets). A few resemble mushrooms.
And lichens, according to Lucking, are the only known form of symbiosis in which the composite organism has a completely different appearance from either of its components.
“Lichens have no organs or definite structures such as leaves,” says Lucking. “The fungus can build almost any shape, as long as it optimizes the ability of the photobiont to produce carbohydrates.” In fact, the shape a lichen takes is an adaptation to its particular environment.
The shape a lichen takes is an adaptation to its environment.
“If you look closely,” says Lucking, “all lichens grow more or less similarly; the variety of shapes is reached by variation of a few simple parameters, i.e. growing horizontal or vertical, attached to or separate from the substrate.
“The colors are caused by a few pigment classes, synthesized by the fungus, that produce shades of grey, yellow-orange, or brown-black, which then mix with the colors of the photobionts. So with variation of a few characters, you get a multitude of morphotypes” — species that look a whole lot different from one another.
“Lichens grow almost anywhere. But they are most diverse in humid ecosystems, especially in mountainous areas or lowland tropical rain forests,” says Lucking. “The most conspicuous lichens can be found among wet mountain forests such as Waikamoi Preserve on Maui, and Koke‘e State Park and Waimea Canyon on Kaua‘i.”
Lucking and Bibiana Moncada, a lichenologist from Colombia, visited sites on O‘ahu, Kaua‘i and Maui, and collected specimens whose DNA they are analyzing at the Field Museum’s state-of-the-art laboratory. They were assisted in the field by Cliff Smith, program manager of the O‘ahu Army Natural Resources Program and a resident lichenologist for nearly fifty years; Pat Bily, invasive-plants specialist with The Nature Conservancy; Philip Thomas, invasive-plants specialist with the Hawaiian Ecosystems at Risk project; Tim Flynn from the National Tropical Botanical Garden; and Daniel Pomaika‘i Kaniaupio-Crozier, a conservation scientist who manages West Maui’s 8,600-acre Pu‘u Kukui Watershed Preserve.
Analyzing the DNA allows the scientists to study the relationships among the different evolutionary types of lichens.
Why the interest?
“Rock and soil lichens are the pioneers in soil formation,” Lucking explains. “Many lichens fix atmospheric nitrogen and serve as biofertilizers, enabling plants to grow. Because they store up to 800 percent of their dry weight of water, lichens regulate atmospheric humidity and the water cycle at the habitat and microhabitat level.”
Lichens can by biological indicators of the health of an ecosystem.
Despite their importance, lichens seem to have been overlooked by early naturalists, perhaps, as Kaniaupio-Crozier suspects, because “many were found in wao akua, the forest realm of the gods. In pre-Contact Hawai‘i, most of those who visited the forest were kahuna [priests]. It was not where the average person would go. When the nineteenth-century naturalists went around and asked, maybe they did not realize not all people had the same knowledge.”
He says his native Hawaiian family has always cherished lichens. Some are edible. Some are used in lei. And forest lichens can be important biological indicators of the health of the ecosystem.
“When certain lichens are wet, I know the bristletails [wingless insects] are healthy,” says Kaniaupio-Crozier. “I listen with a Hawaiian heart. If the snails aren’t healthy, then they won’t be able to do their jobs to keep the trees healthy. In the Hawaiian way of thinking, everything is one thread in the tapestry of life. Everything plays a unique role. As one thing is eliminated, it affects everyone. It is as if you take a thread out of a shirt, it will start to unravel. Every thread is important.”