A study carried out by the National Museum of Natural Sciences (MNCN) of the Higher Council for Scientific Research (CISC) and the Faculty of Veterinary Medicine of the Complutense University of Madrid (UCM) used reproductive technologies to contribute to the survival of the Iberian lynx, one of the … historically most endangered species. The results, published in the journal Theriogenology Wild, show for the first time the possibility of generating embryos of this species after fertilizing in vitro reproductive cells from females who died in accidents with cryopreserved spermatozoa in the species’ biobank.
The Iberian lynx is a species endemic to the Iberian Peninsula. In 2002, the census of less than 100 specimens in the wild led to it being considered the most endangered feline on the planet by the International Union for Conservation of Nature (IUCN). However, in 2024, the species had more than 2,000 animals in the wild, according to data from the Ministry of Ecological Transition and Demographic Challenge (MITECO). In just two decades, conservation, breeding and reintroduction programs, as well as studies on genetics, reproduction and health, have allowed this species to move from “critically endangered” to “vulnerable” status by the IUCN.
Despite this history of recovery, the Iberian lynx today faces significant risks that threaten its survival due to the loss of genetic diversity. Less genetic variability generates inbreeding depression, which reduces the chances of survival and causes the appearance of diseases and a reduction in reproductive capacity. The researchers point out that assisted reproduction techniques could reduce the prevalence of these complications through the management of reproduction of populations in captivity and in the wild.
“Our research offers new options to the lynx conservation program because it makes possible the reproduction of animals that have not had this opportunity, for example because they die prematurely or because they have behavioral problems and do not mate,” explains Eduardo Roldán, CSIC researcher at the MNCN and co-director of the research.
Genetic variability of the species
The reproductive material of the males was obtained through the collaboration of the Iberian Lynx Captive Breeding Centers of Spain and Portugal, which allowed the collection and cryopreservation of sperm for storage in the MNCN Wild Genetic Material and Tissue Bank, which functions as a biobank for the species. The females’ reproductive material was obtained through Wildlife Recovery Centers, which supports the lynx conservation program in the wild. The coordination ensured by the autonomous communities of Andalusia, Castile-La Mancha and Extremadura, MITECO and the Autonomous Body of National Parks, made it possible to obtain the reproductive material of males and females necessary for this work.
The research began with the rescued ovaries, which were transported refrigerated to the laboratory to achieve oocyte maturation under controlled conditions. These oocytes were fertilized and thus generated embryos cryopreserved by vitrification and currently preserved in the Iberian lynx biobank. “We now need to develop methods to transfer these embryos to recipient females, which will undoubtedly help improve the genetic diversity of this species,” explains Ana Muñoz Maceda, predoctoral researcher at UCM and lead author of the work.
Another notable aspect of the study concerns differences due to the time of year the ovaries were saved. “We found that the time of year had a big effect on obtaining embryos. We had more success when they recovered in autumn and winter, the period when lynxes reproduce,” emphasizes María Jesús Sánchez Calabuig, professor at UCM and co-director of the research. “The success obtained, however, is far from ideal, because it is lower than that we obtain with domestic cats, the species we use as a model,” explains Sánchez Calabuig.
Among the factors that influence the results, the authors highlight the key role of the time that passes until injured females are located and their ovaries recovered. To overcome these limitations, the team plans to use alternative methods to obtain oocytes. “It will be necessary to find the least invasive method possible and ensure maximum recovery of oocytes that can be used for in vitro fertilization,” emphasizes Andrea Priego González, predoctoral researcher at UCM and lead author of the study.
Assisted reproduction and genetic management
This work constitutes a major scientific novelty, because it demonstrates that it is possible to produce Iberian lynx embryos in the laboratory from ovaries obtained post mortem and cryopreserved spermatozoa. “Thanks to the sperm that we store in the biobank, we have genetic insurance,” explains Roldán.
These advances open the door to recovering the genetic diversity of specimens that die prematurely, without leaving offspring. They will also make it possible to plan matings of individuals distant in space, belonging to different populations, or distant in time, that is to say belonging to different generations, which will improve strategies aimed at strengthening the genetic diversity of species and, in certain cases, saving genotypes of interest.
“Our results, although initial and still subject to improvement, confirm that reproductive biotechnology can become a key tool to complement conservation efforts and ensure the long-term genetic sustainability of the Iberian lynx,” concludes Sánchez Calabuig.
The project was financed by the Community of Madrid, MITECO, the Ministry of Science, Innovation and Universities, CSIC and MNCN.
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