Reintroduction of lynxes requires large populations
The number of animals released plays a decisive role in successfully reintroducing lynxes.
If only a few lynxes are released to establish a new population, the genetic diversity is too low to secure their long-term survival.
This was recently published by an international research team in the journal «Conservation Genetics». In their study, the authors emphasise the need to strengthen newly established European lynx populations by releasing additional lynxes and implementing other conservation measures.
The Eurasian lynx (Lynx lynx) is the largest European wild cat species and has been protected in the EU since 1992. Its original range, which once covered all of Europe, is today largely confined to protected areas such as national parks. These populations exist only thanks to the efforts of individual countries to protect lynx populations in Europe or to re-establish them in suitable habitats. However, newly established populations face significant challenges: “The populations founded through reintroduction in Europe consist of too few individuals to be self-sustaining. In addition, small populations are particularly vulnerable to losses in genetic variation, since each individual animal accounts for a high percentage of the gene pool of the entire population,” explains Daniel Förster, geneticist at the IZW.
The population in the Bohemian-Bavarian Forest was founded by the release of 5 to 10 lynxes in the 1970s and was later expanded by a further 18 lynxes. The population in the Palatinate Forest-Vosges area was established between 1983 and 1993 through the reintroduction of 21 lynxes. Of these already small numbers, only a portion of the animals — the so-called founder individuals — actually produced offspring. “From a genetic perspective, this means that with so few founder animals, the genetic variation within the newly established population is very limited,” explains Jörns Fickel, co-author of the study and likewise a geneticist at the IZW.
To assess the effect of the number of reintroduced animals on the genetic condition of the two lynx populations, the scientists compared the genetic diversity of the reintroduced populations with that of naturally occurring European lynx stocks. For this purpose, molecular markers in the lynx genome were examined, obtained from fecal, blood, and tissue samples.
In their study, the scientists found that the two newly established populations displayed very low genetic diversity compared to other European lynx populations, meaning there were comparatively fewer gene variants within these populations. The lynx in the Bohemian-Bavarian Forest and the Palatinate Forest-Vosges area represent very small populations that, unlike most other populations studied, did not arise through immigration. An earlier study of a lynx population reintroduced in Slovenia and Croatia had already indicated that small, reintroduced populations suffer from low genetic diversity. The current study now reinforces this finding, thereby contributing to its generalizability. As a result, small populations are often unable to sustain themselves in the long term. According to the scientists, the «Red List» classifications by the International Union for Conservation of Nature (IUCN) — “endangered” for the population in the Bohemian-Bavarian Forest and “critically endangered” for the one in the Palatinate Forest-Vosges area — are therefore entirely accurate, which is why appropriate measures must be taken to strengthen and protect these lynx populations.
For small populations in particular, it is devastating when even a single animal dies before reproducing, whether from natural causes or poaching. “For lynx populations to be permanently established and maintained, it is essential to reduce the illegal killing of lynx,” emphasizes Förster. He and his colleagues also advocate for relocating additional lynx into both populations in order to directly strengthen their genetic diversity. Indirect conservation measures, such as the establishment of wildlife corridors, can furthermore enable genetic exchange between neighboring populations and thus also contribute to strengthening lynx populations.
Publication:
Bull JK, Heurich M, Saveljev AP, Schmidt K, Fickel J, Foerster DW (2016): The effect of reintroductions on the genetic variability in Eurasian lynx populations: the cases of Bohemian-Bavarian and Vosges-Palatinian populations. CONSERV GENET; DOI: 10.1007/s10592-016-0839-0.
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