Devil's toothfish (Cyprinodon Diabolis) live in a cave lake in Death Valley (USA), where the water temperature reaches 32 ° C. For many years, these fish have survived in extreme conditions. The depth of their basin in the rock is more than 100 m, and the sandbank, where individuals could reproduce, runs only in a narrow strip along the edge of the reservoir. Algae serve as food for them. When there is hardly any sunlight for months, the vegetation becomes scarce. Mass extinction is common for this unique species.
According to the results of past studies, it has been assumed that this species of kartozubits separated into a separate population more than 10,000 years ago. But the latest genetic analysis has shown that they inhabit the Devil's Hole (karst caves, connected by passages) for a maximum of several hundred years.
Scientist Christopher Martin and his colleagues told Royal Society magazine that how the animals got into this habitat remains open. There are other populations of fishtooth in Death Valley, but they all had to somehow cross one of the driest and hottest deserts on Earth before ending up in the Devil's Hole.
According to the main version of scientists, this movement was made possible by a major flood. For example, what happened in California in 1862. It is also known that the caviar of the fishfish is sticky, due to which it clings to the plants, which means it could stick to the legs of the birds, and they brought it to the cave. The human factor also cannot be ruled out: local Americans could release fish into the karst lake.
According to geological data, the cave lake "came to the surface" 60,000 years ago, and most of Death Valley was under water for 10,000 years. This could have allowed the kartozubik to move more freely around the region.
The first genetic tests that scientists used to determine the exact age of Cyprinodon Diabolis revealed mitochondrial DNA, the genetic material contained in the "energy factories" of cells. This DNA includes mutations at a regular rate across generations and can be thought of as a kind of “clock”. However, this approach is known to be sensitive to the calibration rules that are applied for the analysis.
Earlier attempts to investigate mtDNA led scientists to the conclusion that the population of the devil fishtooth was formed within 2–3 million years. But geologists rule out this possibility.
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To study rare fish, Dr. Martin and his team have applied the most modern methods of genetic analysis. They began to study thousands of genetic samples, taking into account changes within and between populations using demographic models. Calibration was carried out with more reliable data based on the full variety of kartozubits in Mexico.
According to the results of the study, it can be assumed that the first individuals settled in the Devil's Hole about 105-830 years ago. The ecology of the place has given rise to a pronounced phenotypic identity of this species of karpozubik. They not only became less aggressive, but also lost their dark metallic color, completely lost their pelvic fins. It is still unknown to science whether the loss of this part of the body is a consequence of severe inbreeding for a long time or the result of a forced long-term adaptation to difficult living conditions.
