Pioneer Species - Biodiversity for a Livable Climate

I’m smaller than dust, yet ancient and wise,
I thrive in the harshest of lows and highest of highs.
No mate, no death, no fear of the cold,
I borrow new genes when my own get too old.

Our world follows certain rules. Or at least, that’s what I was taught growing up. Falling objects accelerate at 9.8 meters per second squared in a vacuum. Warm air rises. Diagonally cut sandwiches just taste better. Living things, too, evolve a certain way, survive a certain way, die a certain way.

Or so I thought, anyway.

I was not taught that there are some creatures out there that cheat death, that rewrite their own DNA and survive in conditions that should render said survival impossible. At a moment when humans are trying to hack biology in an effort to live younger, longer, there are creatures out there that have been doing it for millions of years.

Meet the rotifer.

You’ve probably never seen one, but they’re everywhere: in puddles, moss, soil, and freshwater lakes. They look like something from Pandora, spinning through water with wheel-like cilia. Hardly larger than a speck of dust, they don’t roar, they don’t tower over landscapes, and they’re not exactly at the top of any food chain as I know them. But they’ve outlived entire species, survived mass extinctions, and continue to defy the rules of biology we thought we knew.

While rotifers may be practically invisible to our eyes, their impact is not. They play a fundamental role in freshwater ecosystems, drifting through aquatic environments and feeding on algae, bacteria, and other organic debris. Remember my little quip earlier about food chains? Well, it’s sort of a half-truth. They feed on algae, bacteria, and bits of organic debris—basically whatever’s floating around at the microbial level. In doing so, they turn microscopic life into something usable for everything else. They’re one of the first stops in the food web, sustaining creatures far bigger than themselves. Take them out, and the whole darn thing starts to wobble.

Life is full of exceptions, and even the smallest creatures can upend our understanding of what survival, and life itself, really means.

Rule #1: It Takes Two to Tango

A fundamental principle of biology I thought I understood is that species need genetic diversity to evolve and survive. Sexual reproduction is nature’s way of mixing genes, creating stronger offspring that are better adapted to changing environments. Without this reshuffling of DNA, plant and animal species alike face genetic stagnation and, over time, possibly extinction.

Rotifers see it differently.

For tens of millions of years, the bdelloid class of rotifer has lived without sex. They reproduce by cloning themselves over and over, spawning genetically identical offspring generation after generation.

By my logic, this should have led to their extinction long ago. They should have faced great difficulty adapting to changing environments, vulnerable to disease, and trapped in a state of evolutionary stasis. Instead, they’ve flourished.

But how?

By stealing DNA from other organisms. Instead of relying on traditional sexual reproduction, bdelloid rotifers are actually able to absorb genetic material from bacteria, fungi, and even some plants. This process, known as horizontal gene transfer, allows them to patch together their own genes with foreign DNA, essentially hijacking useful traits from unrelated life forms.

It’s a complicated process that, to be honest, I don’t fully understand. But that’s okay, because neither do the scientists studying this stuff. Here’s what they think is happening.

When a bdelloid rotifer dries out (usually in a harsh environment), its DNA begins to crumble and break apart into pieces. When it rehydrates, something strange happens: its cell walls become more permeable, just enough to let in snippets of DNA floating nearby, bits from bacteria, fungi, even plants. Once inside, the rotifer’s cellular machinery picks them up and patches them into its own fragmented genome. It’s like a genetic repair job using whatever foraged parts are lying around. Instead of mixing genes through sex, bdelloids build their genetic diversity by borrowing from the world around them. It’s a little messy, a little miraculous, but it works.

Rotifers can get nutrients from algae they can’t eat directly. A parasitic fungus infects algae and releases spores, which the rotifers can eat, allowing energy to pass from the algae to the rotifer through the fungus.
Image Credit: Virginia Sánchez Barranco, et al. 2020

Rule #2: Death and Taxes

I remember my parents quipping throughout my childhood that there are only two sure things in this life, death and taxes. But while I can’t speak for their fiduciary responsibilities, rotifers have been able to generally cheat the former.

When an organism is deprived of water, it usually dies. Cells shrivel, biological processes shut down, and life ends.

When conditions turn hostile for rotifers, when droughts dry up their ponds, when ice encases them, when the world around them becomes unlivable, rotifers don’t really die. They shut down, entering a sort of paused or stalled state, called cryptobiosis. Their bodies lose nearly all water content, their metabolism grinds to a halt, and for all practical purposes, they are lifeless husks of a microorganism. But give them a single drop of water, and they wake up, pretty much just as they were before.

Some rotifers can survive in this suspended animation for decades. Others have gone far longer. In one of the most staggering discoveries, scientists revived a 24,000-year-old rotifer from Siberian permafrost, and it immediately resumed life, eating, cloning itself, and otherwise carrying on as if it had just taken a nap. I’m not too well-versed on Marvel films, but I’m 99% sure this was basically the plot of a Captain America movie.

Most creatures don’t get a second chance at life, and this individual superpower bodes well for the species as a whole. Limited though it may be, fossil evidence suggests they’ve been around for tens of millions of years, enduring planetary shifts, ice ages, and environmental catastrophes that wiped out far larger and more powerful creatures. I think it’s safe to say they’re well positioned for another few dozen million years, come what may.

notholca rotifer
image credit: Wiedehopf20

The Things We Think We Know

Rotifers challenge what I thought I knew about survival itself. They don’t evolve the way they should, they don’t die when they should, and they have little regard for the biological limits we assume all creatures must adhere to.

Despite their microscopic size, rotifers keep ecosystems running, breaking down organic material, cycling nutrients, and supporting food webs that stretch far beyond their little dominion.

Science is full of rules. They help us understand how the world works. But rotifers are proof that rules aren’t always as rigid as we think. They remind me that life’s possibilities are bigger, weirder, and more resilient than we might imagine.

Brendan Kelly began his career teaching conservation education programs at the Columbus Zoo and Aquarium. He is interested in how the intersection of informal education, mass communications and marketing can be retooled to drive relatable, accessible climate action. While he loves all ecosystems equally, he is admittedly partial to those in the alpine.

Dive Deeper

What tree has adapted to grow directly in lava rock and is a keystone species of the Hawaiian watershed?

‘Ōhi’a Lehua (Metrosideros polymorpha)!

Image Credit: Kevin Faccenda via iNaturalist

The first time I saw the vibrant blossoms of the ‘ōhi’a lehua tree, I was walking on a dirt path in Kauai’s Waimea Canyon State Park, gaping down at the most colorful red and green gorges I had ever seen. Needing a breather from the steep visual plunge, I looked up from the canyon and noticed bright red flowers on the side of the path. As I got closer and could see the plant more clearly, the first thought that popped into my head was how similar the flowers looked to those fiber optic light toys I had played with as a kid. (If you don’t know what fiber optic light toys look like, look them up. You’ll see exactly what I mean.)

After my trip to Waimea Canyon, I saw ‘ōhi’a lehua everywhere. When I drove along the coast between the beach and the sloping mountains, when I hiked the volcanic craters of Haleakala, and when I visited parks and gardens across the islands that protect native plants and animals. ‘Ōhi’a lehua is the most common native tree in Hawaii, so seeing its fiery red, orange, or yellow blossoms every day felt so very ordinary. But ‘ōhi’a lehua is far from ordinary.

Image Credit: Ed Sharron via iNaturalist

Let Me Introduce You to My New Friend, ‘Ōhia Lehua

Endemic to the six largest islands of Hawaii, ‘ōhi’a lehua is the dominant tree species in native forests, present in approximately 80% of the total area of these ecosystems and covering close to one million acres of land across the state. Depending on where exactly it grows, its size can vary widely, from a small shrub to a large tree. Found only in the Hawaiian archipelago, ‘ōhi’a lehua grows at elevations from sea level to higher than 9000 feet, and in a variety of habitats like shrublands, mesic forests (forests that receive a moderate amount of moisture throughout the year), and more wet, or hydric, forests.

You can easily identify the ‘ōhi’a lehua blossoms by their mass of stamens – the part of the flower that produces pollen – which are slender stalks with pollen-bearing anthers on the end. It’s what made me think the ‘ōhi’a lehua looked exactly like those fiber optic light toys. These powder puff-like flowers are most often brilliant shades of red and orange, but yellow, pink, and sometimes even white ones can be found.

‘Ōhi’a lehua grows slowly, reaching up to 20-25 meters (66-82 feet) in certain conditions.

With a little help from the wind, the seeds of ‘ōhi’a lehua travel from the tree and settle in cracks in the ground of young lava rock. It is, in every sense, a true pioneer plant. As one of the earliest plants to colonize and grow in fresh lava fields, ‘ōhi’a lehua stabilizes the soil and makes it more habitable for other species.

Even though ‘ōhi’a lehua can blanket Hawaii’s native forests, this flowering tree also grows alone, as you can see in the photograph below. Plants like ‘ōhi’a lehua fill me with happiness because they are able to grow in the most harsh, barren, and disrupted places, and they make it possible for other species to do the same. Plants like ‘ōhi’a lehua fill me with surety that even though sometimes poorly treated, the natural world will continue to be strong. Plants like ‘ōhi’a lehua make me believe in the resilience of nature.

Arid, rocky, Mediterranean coast. (Via Pexels)

How ‘Ōhi’a Lehua Cares for the Hawaiian People

Biodiversity forms the web of life we depend on for so many things – food, water, medicine, a stable climate, and more. But this connection between human beings and natural life is not always clear, understood, or appreciated. But there is a concept in Hawaiian culture called aloha ‘āina, or love of the land, which teaches that if you take care of the land, it will take care of you. The ‘ōhi’a lehua in particular takes care of the Hawaiian people in a pretty special way.

One of the most important characteristics of this flowering evergreen tree is that it’s a keystone species, protecting the Hawaiian watershed and conserving a great amount of water. The way I see it, ‘Ōhi’a lehua is an essential glue that holds Hawaii’s native ecosystems together. The leaves of ‘ōhi’a lehua are excellent at catching fog, mist, and rain, replenishing the islands’ aquifers and providing drinking and irrigation water for Hawaiian communities. ‘Ōhi’a lehua’s ability to retain water, particularly after storms, not only makes that water accessible for other plants, but it helps mitigate erosion and flooding. The tree provides food and shelter for native insects, rare native tree snails (kāhuli), and native and endangered birds like the Hawaiian honeycreepers (‘i’iwi, ‘apapane, and ‘ākepa). ‘Ōhi’a lehua trunks protect native seedlings and act as nurse logs, providing new plants with nutrients and a growing environment.

‘I’iwi, the Scarlet Hawaiian Honeycreeper, perched on an ‘ohi’a tree (Image Credit: Nick Volpe)

The Myth of ‘Ōhi’a Lehua

‘Ōhi’a lehua may have a disproportionately large effect on Hawaii’s ecosystems as a keystone species, but its presence as a meaningful part of Hawaiian culture could be even larger. There are many versions of mo’olelo (story) about the origin of the ‘ōhi’a lehua tree, but the most common one is about young lovers named Ōhi’a and Lehua. Pele, the goddess of the volcano, changed herself into a human woman and tried to entice ‘Ōhi’a. When he denied her, Pele became enraged and transformed ‘Ōhi’a into a tree. When Lehua found out, she was so heartbroken that she prayed to the gods to somehow help her reunite with him. Answering her prayers, the gods transformed Lehua into a flower and placed her on the ‘ōhi’a tree’s limbs. To this day, it’s believed that whenever a lehua flower is picked, the skies will open up and rain will fall, because the lovers have been separated.

‘Ōhi’a Lehua as a Cultural Symbol

In Hawaiian culture, the ‘ōhi’a lehua is a symbol of love, resilience, and ecological harmony. The transformation of Ohia and Lehua into tree and flower represents the inseparable bond between two people who love each other, and between the tree and its flowers. The term pua lehua, or lehua flowers, is often used to describe people who express the same grace, strength, and resilience of the ‘ōhi’a lehua. Pilina, a Hawaiian word that means “connection” or “relationship,” is an important value in Hawaiian culture because it is a critical way for people to connect with and understand the world around them. The ‘ōhi’a lehua tree is a symbol of pilina, and embodies this relationship between the Hawaiian landscape and its people.

Hula dancers performing at the Merrie Monarch Festival
Thomas Tunsch (**CC BY-SA** )

The ‘ōhi’a lehua is also incredibly important to hula. Hula is the narrative dance of the Hawaiian Islands, and it is an embodiment of one’s surroundings. Dancers use fluid and graceful movements to manifest what they see around them and tell stories about the plants, animals, elements, and stars. ‘Ōhi’a lehua trees and forests are considered sacred to both Pele, the goddess of the volcano as you may recall, and Laka, goddess of hula. To enhance their storytelling and evoke the gods, dancers traditionally wear lehua blossoms or buds in lei, headbands, and around their wrists and ankles.

The Dependability of ‘Ōhi’a Lehua

‘Ōhi’a lehua has long been a part of daily life. Historically, the hardwood of the tree was used for kapa (cloth) beaters, papa ku’i ‘ai (poi pounding boards), dancing sticks and ki’i (statues), weapons, canoes, and in the construction of houses and temples. Today, the tree’s wood is used for flooring, furniture, fencing, decoration, carving, and firewood. ‘Ōhi’a lehua blossoms decorate altars for cultural ceremonies and practices. Flowers, buds, seeds, and leaves form the base of medicinal teas that can stimulate appetite and treat childbirth pain.

Threats to ‘Ōhi’a Lehua

As a native tree, ‘ōhi’a lehua competes with invasive species for moisture, nutrients, light, and space. Plants like the strawberry guava plant (Psidium cattleyanum) grow in dense thickets and block the growth of ‘ōhi’a seedlings. The invasive fountain grass (Pennisetum setaceum) can dominate barren lava flows, making it difficult for ‘ōhi’a to compete. ‘Ōhi’a lehua is also threatened by non-native animals. Hooved animals like pigs, cattle, goats, and deer disturb the soil, eat sensitive native plants, and trample the roots of ‘ōhi’a lehua trees.

The most dangerous threat to ‘ōhi’a lehua is a virulent fungus called Ceratocystis fimbriate, which attacks the tree’s sapwood, preventing it from uptaking water and nutrients, and killing the tree within weeks. It’s been given the name Rapid Ohia Death (ROD) because of how quickly it suffocates the tree, turning the leaves yellow and brown and the sapwood black with fungus. Infections spread through a wound in the bark, which can be caused by animals trampling roots, lawn mowing, or even pruning, and can be present in the tree for up to a year before showing symptoms. ROD is spread by an invasive species of wood boring Ambrosia beetle that infests the tree and feeds off the fungus. When colonizing trees, the beetle produces a sawdust-like substance made of excrement and wood particles called frass, which can contain living fungal spores that get carried in wind currents and spread by sticking to animals and human clothes, tools, and vehicles.

Since its discovery in 2014, ROD has killed more than one million ‘ōhi’a lehua trees across 270,000 acres of land, making it a significant threat to biodiversity and cultural heritage. The International Union for Conservation of Nature (IUCN) classifies ‘ōhi’a lehua’s conservation status as vulnerable, and has recorded a decline in mature trees since 2020. Because ROD can spread long distances, it has the potential to wipe out ‘ōhi’a lehua across the entire state. If ‘ōhi’a lehua disappears, it will lead to a collapse of the Hawaiian watershed and radically change the ecosystem.

How the Hawaiian People Care for ‘Ōhi’a Lehua

Scientists, researchers, and native Hawaiians are working together to ensure the long-term health and resilience of ‘ōhi’a and Hawaii’s native forests by mitigating the spread of Rapid Ohia Death. Hawaii’s Forest Service monitors the land to track the spread of ROD and mortality of trees, has developed sanitation and wound-sealing treatments, and collaborates with hunters and game managers to reduce disease transmission. Scientists rigorously test ‘ōhi’a trees to understand the disease cycle, find out how it can be broken, and to identify trees resistant to the infection that could be used in potential reforestation efforts.

To prevent the spread, Hawaii has announced quarantine restrictions, travel alerts, and sanitation rules. If you are shipping vehicles between islands, you should clean the entire understory with strong soap to remove all mud and dirt from the tires and wheel wells. People who go into ‘ōhi’a forests are advised to avoid breaking branches or moving wood around, to clean their shoes and clothes, and to decontaminate any tools used with alcohol or bleach to kill the fungus. Even hula practitioners are forgoing the use of ‘ōhi’a lehua.

Orange ‘ōhi’a lehua blossom (Image Credit: Joan Wasser via National Park Service)

Mālama the ‘āina

Mālama the ‘āina is a phrase that means to care for and honor the land. ‘Ōhi’a lehua is a wonderful representation of the interconnection between people and nature and I hope learning about this beautiful tree has encouraged you to appreciate the relationship we have with the Earth and what the natural world does for us.

Remember, if you take care of the land, it will take care of you.

Abigail

Abigail Gipson is an environmental advocate with a bachelor’s degree in humanitarian studies from Fordham University. Working to protect the natural world and its inhabitants, Abigail is specifically interested in environmental protection, ecosystem-based adaptation, and the intersection of climate change with human rights and animal welfare. She loves autumn, reading, and gardening.

Sources and Further Reading:

Creature: Pioneer Species

Featured Creature: Rotifers