How could Iberian lynx, weakened by inbreeding, be supported in their population recovery? A study suggests that cross-breeding with the Eurasian lynx could be good for them. As it turned out, this naturally enriched the genetic diversity of the Iberian lynx thousands of years ago. The researchers say that some “fresh blood” from relatives could also help other endangered and genetically impoverished animal species to improve their vitality.
They are smaller, have longer beards and more distinctive fur patterns than their relatives from the north: On closer inspection, the Iberian lynxes (Lynx pardinus) differ significantly from the Eurasian lynxes (Lynx lynx). Studies also show that the two species split up around a million years ago. The Iberian lynxes, also known as leopard lynxes, were once widespread in what is now Spain and Portugal. But especially in the 20th century, their stocks declined rapidly. They fell victim to hunting, habitat loss, traffic and cat diseases until fewer than a hundred remained. Subsequent conservation efforts were successful, but the Iberian lynx is still considered one of the rarest cat species in the world and its continued existence is threatened.
Problematic inbreeding population
One problem is the low genetic diversity due to the strong inbreeding in the small remaining stocks. This makes the animals vulnerable to disease and fundamentally reduces their ability to adapt to changes in their environment. As part of their study, researchers led by María Lucena from the Doñana Biological Research Station in Seville have now investigated the question of what the genetic diversity of the Iberian lynx was like in the past. To do this, the scientists analyzed DNA that they extracted from three fossil specimens of the Iberian lynx. One comes from Andújar and has been dated to be around 4,300 years old. Another specimen, around 2,500 years old, came from Alcanar in Catalonia and the third lynx lived around 2,100 years ago in what is now Portugal.
The researchers actually expected to find a relatively high level of genetic diversity in the ancient animals compared to today's. But the comparisons of the sequencing results led to a big surprise: the genetic diversity in the ancient lynxes was not richer, but rather poorer than in today's animals. The team was then able to show the cause of the increase in genetic diversity: According to this, the genetic heritage of the Eurasian lynx had flowed into the genome of the Iberian lynx through mixing. “It turned out that modern lynxes share more genetic material with their sister species, the Eurasian lynx, than older lynxes. “This suggests that there has been genetic exchange between the two species over the last two thousand years,” says Lucena. In line with this, the analysis results also showed that the younger of the specimens examined - from Catalonia and Portugal - have more genetic variants of the Eurasian lynx than the older specimen from Andújar.
Hybridization with potential for species conservation?
It is also known from other animal species that such mixing can occur across species boundaries. Most animals avoid this, but it does happen under certain circumstances. Specifically, the researchers suspect that the genetic exchange occurred when the distribution areas of the two species bordered each other for a while. The Iberian lynx could therefore have also occurred north of the Pyrenees during the relevant time window, or some Eurasian lynx roamed through the north of the Iberian Peninsula. After these occasional interbreedings, the genetic heritage of the Eurasian lynx then spread to all present-day leopard lynx populations. This in turn is an indication that this genetic material introduced across species boundaries had a beneficial effect on the animals.
According to the researchers, the study results are not just an interesting insight into the developmental history of the Iberian lynx. They could also be relevant to efforts to protect endangered big cats – and beyond. The study once again brings into focus the controversial question of whether the introduction of distantly related individuals into endangered and genetically impoverished populations could represent a conservation strategy.
“Our results add to the accumulating evidence of natural mixing and introgression in the genomes of many species and show that this can lead to an increase in the existing genetic diversity in genetically severely eroded populations,” says co-author Michael Hofreiter from the University of Potsdam. “In this respect, the strict avoidance of interspecific sources in genetic restoration measures may need to be reconsidered and carefully examined. “Especially when, as with the Iberian lynx, there is no additional population of the same species, so a closely related species could be the only source of new genetic diversity,” says the scientist.
Source: University of Potsdam, specialist article: Nature Ecology & Evolution, doi: 10.1038/s41559-023-02267-7