Vivian Underhill, a researcher formerly at Northeastern University, has been studying this unexpected phenomenon.

“Tulare Lake was the largest body of fresh water west of the Mississippi River. It’s really difficult to imagine that now,” she says.

Tulare Lake returns

Often dubbed the “ghost lake,” Tulare Lake vanished about 130 years ago due to extensive human intervention.

But in the spring of 2023, after massive winter storms and significant snowmelt from the Sierra Nevada, the lake roared back to life.

The water overwhelmed human-made systems designed to drain the basin, submerging thousands of acres of fertile farmland that once produced pistachios, almonds, cotton, and safflower.

The reborn lake stretches out with a seemingly endless blue horizon.

Yet, unlike Lake Tahoe’s cool breezes and recreational appeal, Tulare Lake offers little respite from the heat. The air is still, and a thin layer of high clouds does little to shield the sun.

Nature reclaims the land

Despite the challenges, the lake’s return has revitalized local ecosystems. Ducks, egrets, and other waterfowl have flock to its shores.

Frogs now wade at the water’s edge, ready to dive in at the slightest disturbance. Tule grass has begun to sprout along the shoreline, signaling a revival of plant life that hasn’t been seen here in generations.

Underhill notes the historical significance, saying, “Once, there was so much water that a steamship could carry agricultural supplies from the Bakersfield area up to Fresno and then up to San Francisco.”

That’s nearly 300 miles of navigable waterways that connected communities and supported commerce.

Tulare Lake hidden in plain site

To travelers passing through the arid San Joaquin Valley today, the existence of such a vast lake seems almost mythical.

“It’s hard to imagine such a large body of water coexisting alongside such an arid landscape,” Underhill remarks. Yet, in the 1800s, “Fresno was a lakeside town.”

Back then, Tulare Lake was fed primarily by snowmelt from the Sierra Nevada.

“There’s no natural outlet within the valley,” Underhill explains, “so the water collects to form a lake.” The indigenous Tachi Yokut tribe called it “Pa’ashi,” and it was central to their way of life.

The disappearance of Tulare Lake began in the late 1850s and early 1860s.

“The state of California’s desire to take public land and put it into private ownership propelled the lake’s decline,” Underhill explained.

“When we say ‘public land,’ that is historically indigenous land that the state of California blanket-proclaimed as ‘public.’”

This process, known as “reclamation,” aimed to convert inundated or desert land into arable farmland.

“If people could drain that land,” Underhill says, “they would be granted ownership of parts of that land. So there was a big incentive for white settlers to start doing that work.”

This led to the construction of hundreds of irrigation canals crisscrossing the valley, diverting water away from the lake.

Modern-day concerns

Today, the reemergence of Tulare Lake poses new challenges. The floodwaters have engulfed private lands, turning fields into vast stretches of water.

Signs warning against trespassing dot the shoreline, reminding everyone that wading or boating is technically prohibited.

More troubling is what’s hidden beneath the surface. The waters have submerged storage sheds containing fertilizers and chemicals, manure piles, electrical wires, and sharp farm machinery.

These hazards not only pose risks to anyone venturing into the lake but also raise environmental concerns about contamination.

Uncertain future of Tulare Lake

Local officials now speculate that this latest incarnation could also take years to fully recede.

“California just got inundated with snow in the winter and then rain in the spring,” Underhill points out.

Such weather patterns accelerate snowmelt, causing rapid runoff into the basin where Tulare Lake sits.

“All that snow and rain in the Sierra still runs into the depression where Tulare Lake once stood,” she adds.

Reflecting on the past

The story of Tulare Lake is not just about water returning to a dry basin; it’s a narrative intertwined with history, culture, and environmental change.

The lake’s disappearance was a result of deliberate actions to reshape the land for agriculture, often at the expense of indigenous communities and natural ecosystems.

Underhill emphasizes the colonial undertones of this transformation. “It was a deeply settler colonial project that proceeded in fits and starts,” she says.

The push to privatize land and the incentives offered for reclamation led to dramatic alterations of the landscape.

Why does any of this matter?

As Tulare Lake reclaims its historic footprint, it serves as a reminder of nature’s resilience and the lasting impacts of human intervention.

The revival has brought back species that haven’t been seen in the area for decades, offering a glimpse into what the region might have looked like before extensive farming took over.

At the same time, the challenges posed by the lake’s return highlight the complexities of balancing human needs with environmental stewardship.

The submerged farmlands represent significant economic losses, and the potential environmental hazards lurking beneath the water pose risks that will need to be addressed.

As Underhill aptly puts it, witnessing the lake’s return is both surprising and profound. It challenges us to reconsider our relationship with the land and the long-term consequences of our actions.

Published in the journal Nature Ecology & Evolution, the research reveals how these mysterious animals defied expectations by diversifying in the harsh, resource-poor environment of the bathypelagic zone—the open ocean depths ranging from 3,300 to 13,000 feet below the surface.

From the seafloor to open waters

The study, led by biologists including Kory Evans of Rice University and his former undergraduate student Rose Faucher, investigated the evolutionary progression of anglerfish (Lophiiformes) as they moved from seafloor habitats to the deep sea’s open waters.

By employing advanced genetic analysis and 3D imaging of museum specimens, the researchers reconstructed the anglerfish’s evolutionary tree and identified the morphological innovations that enabled them to thrive in one of Earth’s most challenging environments.

Unique adaptations of deep-sea anglerfish

While anglerfish are famous for their bioluminescent lures that dangle from their heads to attract prey in the deep sea’s eternal darkness, their evolutionary tale encompasses much more than this notable feature.

The study revealed that deep-sea pelagic anglerfish (ceratioids) descended from benthic, or seafloor-dwelling, ancestors.

These ancestors inhabited the continental slope before venturing into the bathypelagic zone’s open waters—a shift that paved the way for rapid evolutionary changes.

The ceratioids developed characteristics such as larger jaws, smaller eyes, and laterally compressed bodies—adaptations suited to an environment with scarce food and no sunlight.

Surprising diversity of anglerfish

Despite these directional trends, ceratioids exhibited remarkable variability in body shapes, ranging from the typical globose anglerfish to elongated forms like the “wolftrap” phenotype, which features a jaw structure resembling a trap.

This was the most unexpected finding of the study, as the bathypelagic zone did not limit evolution as previously thought, despite its apparent lack of ecological diversity.

Instead, anglerfish achieved high levels of phenotypic disparity, surpassing their benthic relatives in both shallow and deep waters.

This suggests that, rather than being constrained by the deep sea’s environmental challenges, ceratioids explored new evolutionary avenues, diversifying their body forms and hunting strategies.

“With their unique traits like bioluminescent lures and large oral gapes, deep-sea anglerfish may be one of the few documented examples of adaptive radiation in the resource-limited bathypelagic zone,” said Evans, a co-corresponding author on the paper and assistant professor of biosciences.

“These traits likely gave anglerfish an edge in exploiting scarce resources and navigating the extreme conditions of their environment, although we don’t have strong evidence directly linking this diversity to this kind of resource specialization.”

Evans pointed out that the research allows for the possibility that nonadaptive processes, such as relaxed selection or random mutations, might have also contributed to the observed variability.

Anglerfish evolutionary trends

The researchers also compared fish groups across different habitats and uncovered more surprising results.

Coastal species like frogfish, which live in diverse and productive coral reef environments, displayed much lower rates of evolutionary change than their deep-sea counterparts.

“The idea that a resource-poor, homogenous environment—like being surrounded on all sides by nothing but water – would produce diverse body and skull plans is really counterintuitive in this field,” said Faucher, who was co-first author of the paper along with Elizabeth Christina Miller, a postdoctoral fellow at the University of California, Irvine.

“When fish have different features to interact with, like corals and plants in shallow water or sand and rocks on the seafloor, that’s when we would expect fish to have a lot of variation in shape. Instead, we’re seeing it in these deep-sea fish who have nothing but water to interact with.”

Methodology and breakthrough findings

To carry out this study, the researchers utilized a combination of advanced methods. They constructed a phylogeny of anglerfish using data from 1,092 genetic loci across 132 species.

This represented about 38% of the described species and was supplemented by fossil calibrations and genomic data to estimate divergence times and ancestral habitats.

Morphological data were gathered from museum specimens, including linear body measurements and 3D skull shape analyses via micro-CT scans.

To assess evolutionary trends, they applied phylogenetic comparative methods to evaluate phenotypic and lineage diversification, while disparity analyses measured the extent of morphological variation across anglerfish groups and habitats.

They then used Bayesian models to reconstruct ancestral habitats, revealing that ceratioids originated from benthic ancestors before moving to the pelagic zone.

Finally, principal component analyses visualized how anglerfish occupied different regions of phenotypic space, shedding light on evolutionary trends in body, skull, and jaw shapes.

“Anglerfish are a perfect example of how life can innovate under extreme constraints,” said Evans. “This work not only enhances our understanding of deep-sea biodiversity but also illustrates the resilience and creativity of evolution.”

Understanding life in extreme environments

The significance of this study extends beyond the evolutionary history of anglerfish. It offers valuable insights into how life adapts to extreme environments.

The deep sea is one of Earth’s least understood ecosystems, yet it plays a crucial role in global biodiversity and the planet’s carbon cycle.

Understanding how organisms like anglerfish succeed in such conditions helps scientists predict how life might respond to environmental changes, including those caused by climate change.

Moreover, the study addresses broader questions in macroevolution: how new species arise, adapt, and diversify.

By demonstrating that even resource-poor environments can foster significant evolutionary radiation, the research challenges conventional wisdom and opens new pathways for studying evolution in extreme habitats.