The Iberian lynx is the threatened animal with the least genetic diversity in the world and this complicates its future in a changing world. However, the comparison between specimens from between 4,000 and 2,000 years ago now shows how in the past it had even less variety of genes. A work recently published in Nature Ecology & Evolution reveals that, in relatively recent times, Iberian and boreal lynxes crossed paths more than once in northeastern Spain. That mixture diversified the genetic pool and could help the survival of the first ones.
At the beginning of the century, when the extinction of the Iberian lynx seemed inevitable, some scientists proposed crossing lynxes from Sierra Morena, where there were 53 left, with those from Doñana, where there were 41. Many conservationists raised their hands on their heads, considering it an anathema. In just 20 years, the population has risen to 1,668 felines, a third of them cubs, which have expanded their territory from the south of Portugal to Murcia, passing through Extremadura and the mountains of Toledo, even being seen in the southwest of Madrid. . Although success has many fathers and mothers, the CSIC researcher at the Doñana Biological Station, José Godoy, remembers that “the population of the park was very committed, with a high level of consanguinity, and the fact of crossing it with the population of Andújar meant restoring its genetics, also restoring its ability to grow, its demographics.”
Godoy, who leads the Iberian lynx genetic program, is the senior author of this new study that confirms that specimens of this species mated with boreal lynxes and had offspring, thus diversifying their genome, something that they have been able to observe after comparing genetic data from specimens of both species from the present and the past. Specifically, the research was based on the sequencing of the genome of three lynxes that lived in the Iberian Peninsula 2,070 years ago, 2,570 years ago, the second, and 4,270 years ago, the third. They then compared them with that of around thirty current Iberian lynxes from the two original populations (Andújar and Doñana) and with another dozen boreal lynxes from various points, from Germany to Siberia. To have all the pieces of the puzzle, they also included the genetic information of a boreal lynx that lived in what is now Vizcaya.
They were surprised with the results. As they went back in time, the genetic diversity of the remains was lower and, the closer to the present, the greater the genetic closeness between Iberian and boreal lynxes. “We knew that the genetic diversity of the Iberian is very scarce [está entre las más reducidas de entre los mamíferos], but we were left wondering to what extent it was,” says Godoy. This diversity is a key tool for survival. “In general, it is considered necessary to adapt to whatever comes, to adapt to environmental changes,” adds the CSIC scientist. “The Iberian lynx is always down there, among the species that have the least diversity, and that worries us because, to what extent can a species survive in the long term without genetic diversity, and even more so taking into account the rate at which the environment is changing “, completes Godoy.
However, the lynx has been on the knife's edge for millennia. The genetics of lynxes from 4,000 years ago were less varied than those of today and that did not end with them. How has it survived? “It's a mystery, we don't know,” Godoy acknowledges. But his work points to a possibility: “it could be that the Iberian lynx was rescued, let's put it that way, after hybridization processes with the boreal lynx.” At least that's what the data from his new study indicates. The genetic diversity of current Iberians is very low, but higher than that of their ancestors, and this can only be explained by successive crossbreeding events with the Boreal. This is what they see both in the specimen recovered at the La Moleta del Remei site (Alcanar, Tarragona), dated to about 2,520 years ago, and in the one at Monte Molaio (Algarve, Portugal) 500 years later. Furthermore, everything indicates that the flow, the loan of genes, was from the Boreal to the Iberian.
“When they are not far away, are such encounters actively prevented from occurring or allowed naturally as they have happened in the past?”
The crossing, the exchange of genes, does not imply that the Iberian lynx stops being one, in the same way that current humans do not stop being one because they carry up to 4% of Neanderthal genes. Therefore, the authors of this research raise the need to change the conservation paradigm. “We must banish this idea that the species to be conserved must be unique, that they be kept in watertight compartments, when it is neither real nor natural,” says biology and geography professor and first author of the study, María Lucena. They are not considering introducing boreal lynx genes into the Iberian gene pool. It is neither considered nor seems necessary, given the success of the recovery program. “We simply highlight the fact that while they were in contact it seems that there was genetic exchange and what we propose is that this will pose a challenge for future management because it may be that at some point the Iberian lynx contacts the boreal lynx” . In fact, there are plans to recover this species, of which at least one pair is known to exist in the Pyrenean mountain range. “When that happens, when they are physically not far away, which would indicate that the two populations are recovering, what will have to be considered is what is done at the management level, is it actively prevented that these encounters occur or is it allowed? naturally as they happened in the past?
Juan Jiménez, from the Wildlife Service of the Generalitat Valenciana, compiled and published in 2018 a work with dozens of references to the cerval wolf, a creature sighted in the northeast of the country, from the Basque Country to Castellón as late as 1935, during the Second Republic. This cerval wolf, or tiger or gatillop, as it was also called, was nothing other than the boreal lynx. A feline similar in height to the Iberian, but much more robust and twice the weight. The work of Jiménez, who has not participated in the current one, was added to previous ones such as that of Miguel Delibes de Castro from 2013, which recounted the presence of the boreal in much of the north until the 20th century. “There was no clear border between the two species. In fact, their territories overlapped, which would lead to hybridization events,” he says. This helped, at the time, he recalls, “to save the Iberian lynx by bringing together specimens from two populations, something that the conservationist world did not like.” But this is something else, it is natural hybridization between two species. Fortunately, the 563 Iberian lynx cubs that there were in 2023 delay sine die the idea of rescuing the emblem of the Iberian fauna with felines from outside.
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