The Iberian lynx is one of the most genetically depleted feline in the world. This is the main conclusion of a CSIC's research, which confirms what it was widely assumed: the existence of an extensive genetic shading in the only remaining lynx populations, and as a consequence, their endangered situation.
Scientist analysed 167 different lynxes from the two surviving and isolated settlements. These are located in Andalusia, within the protected park of Doñana and it's surroundings, and in the Sierra de Andújar, in Sierra Morena Mountains. They had to trap animals to collect samples, dig in their dens to find biological remains, and extract suitable chunks from individuals found dead in previous field researches and ongoing population monitoring.
The research leaded led by José Antonio Godoy who worked with M Casas-Merce, L Soriano, and J.V López-Bao, all of them scientists at the Estación Biológica de Doñana The genetic analysis shows that both populations have low diversity and have accumulated high levels of inbreeding, due to their small size and their isolation from other settlements. Looking over the other feline species studied so far, scientists found that the Iberian lynx's genetic is more impoverished than most of them, even those that have also small populations like the cheetah in Namibia or the Ngorongoro Crater lions.
Despite both lynx populations show signs of genetic erosion differences between them are noteworthy In this regard Doñana's inhabitants have a 30% less diversity than Andujar's, "which is concordant with its longer isolation and lower population size". Lukily, they have preserved a different subset of the ancestral genetic information, wich means that an appropriate management programme would increase the variety and health of the species, explains Godoy.
At the same time, scientists found high inbreeding levels in both populations,accumulated after decades of matings between relatives. Moreover, the average inbreeding in Andújar is similar to that expected for the offspring of half-sibs, while the value for Doñana is so high that all lynxes are so alike that you could think that comes from self-fertilization.
Researchers argue that Doñana's situation is connected with being small and isolated for nearly a century, much longer than Andújar. In fact, the study estimates that Doñana lynxes have remained isolated for around 84 years and Andujar for 24 years. While the former was already at low population sizes since the 1950s, Andújar has been declining progressively since then, recieiving till recently individuals from other surrounding populations that have disappeared.
Within Andujar, researchers found shallower genetic differences between two separated breeding areas that had no connection for some time, one around Yeguas river and another by the Jándula river.
Scientists consider that the "low levels of genetic diversity are probably the consequence of the recent demographic contraction and isolation." However, it is possible that lynx decline started much earlier, as a signal was found for a much older bottleneck, dated between 450 and 900 years ago.
Lynx populations have been impacted by agricultural and livestock expansion across the Peninsula, which also brought it's direct prosecution as a competitive predator. These same circumstances, plus the decline of their main prey, the rabbit, boosted the more recent fragmentation of the population and it's contraction. By 1980 only 1.100 specimens remained in the Southwest of the Iberian Peninsula, and only twenty years later their geographical range had been reduced by 93%. By 2002 seven of the nine remaining populations had disappeared, leaving the current two as the last remnants of the once abundant species, and harbouring not more than 102 lynxes in total. This year the species was recognized as critically endangered by the International Union for Conservation of Nature.
Scientists highlight that the already low viability of the Iberian lynx "might be further compromised by its low genetic diversity and high inbreeding levels". As a consequence, they concluded that "translocations between populations should be encouraged in order to restore genetic diversity" and claim for a program which integrates "genetic management of captive, wild and reintroduced populations" to ensure the persistence of this species.
The main aim of this research is to generate the first map of the Iberian lynx genome, which will provide important information on the evolution of this species and on the genetic consequences of its decline.
The lynx genomic sequence has already been identified by CNAG and is in the process of being assembled. When the process ends, in 2012, the researchers will face a new challenge: interpret it and compare it to other felid genomes.