A study carried out by researchers at the Spanish National Museum of Natural Sciences and the Estación Biológica de Doñana, both adscribed to CSIC, establishes that inbred lynxes tend to have higer levels of abnormal sperm.
The scientists evaluated two critically endangered species that live in the South of the Peninsula Iberica, lynxes and the Mohor gazelle. The feline only subsists in two isolated areas, Doñana and Sierra Morena, meanwhile Mohor gazelle lives in captivity at the Parque de Rescate de Fauna Sahariana in Almería. For the latter species, no wild animals remain.
They were selected because in both cases "current populations are small and consanguineous matings are frequent", as a consequence they are ideal to study inbreeding depression, this is to analyze the relation between inbreeding and fitness decreases. Semen quality is a good trait to follow because it is often affected by inbreeding and it is an important component of male fitness.
Previous studies had shown that Iberian lynx had in average a low proportion of normal sperm, when compared to other felids. This new research, published in Conservation Biology, shows that this can be attributed, at least in part, to inbreeding.
To reach this goal scientst trapped the animals, who were anesthetized to facilitate taking samples of blood and also of semen via electroejaculation. From 2001 through 2005 they collected samples from 22 male Mohor gazelles and did the same to 20 male Iberian lynxes from 2005 through 2008.
The research concludes that gazelles and lynx have low diversity levels and the effect of inbreeding on sperm quality is strong in both species. In these species, as in humans and most other animals, each cell harbors two copies of every gene in the genome, one inherited from each of the parents, but in inbred individuals these two copies are often identical, as they were shared by both parents because they were relatives.
This means that inbred individuals have an increased chance of bearing two defective copies – and thus no normal copies- of certain genes; when this happens to genes inovolved in sperm development the result is an increased level of abnormal sperm. As a consequence, those males "are likely to have low fertility and will limit the reproduction of females they mate with".
This is just one aspect in which inbred individuals might be less fit. For Iberian lynx some other components of reproduction or survival might as well be affected by inbreeding, but this is the first direct evidence for the occurrence of inbreeding depression in this species.
The study led by Montserrat Gomendio in collaboration with María José Ruiz-López; Natalia Gañan, José Antonio Godoy; Ana Del Olmo; Julian Garde; Gerardo Espeso; Astrid Vargas; Fernando Martinez and Eduardo Roldán.
Scientist call for banks of semen to preserve the DNA of as many males as possible both from captive programs and wild populations with the aim of boosting diversity through specific plans. In this way, the genes carried by these animal can be preserved and, in combination with assisted reproduction techniques, eventually transferred to the new generations, even after the animal's death.
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.