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For suc­cess­ful rein­tro­duc­tion of lynx into the wild, the num­ber of released ani­mals is cru­cial. If only a few lynx are rein­tro­duced to found a pop­u­la­tion, the genetic diver­sity is too low to ensure their long-​term sus­tain­abil­ity. These find­ings have been pub­lished on 4 April in the sci­en­tific jour­nal “Con­ser­va­tion Genet­ics” by an inter­na­tional research team. The researchers high­light the need to strengthen newly estab­lished Euro­pean lynx pop­u­la­tions by addi­tional translo­ca­tions of lynx as well as other con­ser­va­tion measures.

Sci­en­tists of the Ger­man Leib­niz Insti­tute for Zoo and Wildlife Research (IZW), the Bavar­ian For­est National Park (Ger­many), the Pol­ish Acad­emy of Sci­ences (Poland) and the Russ­ian Acad­emy of Sci­ences (Rus­sia) inves­ti­gated the genetic sta­tus of two lynx pop­u­la­tions in the Bohemian-​Bavarian and Vosges-​Palatinian forests in cen­tral Europe.

Lynx his­tory in Europe
The Eurasian lynx (Lynx lynx) is the largest Euro­pean cat species and has been pro­tected in the EU since 1992. Orig­i­nally spread through­out all of Europe, the species is now mainly lim­ited to pro­tected areas such as national parks. Cur­rent pop­u­la­tions only exist because coun­tries have invested a con­sid­er­able effort to pro­tect lynx in Europe or to rein­tro­duced them to suit­able habi­tat in its for­mer range. Rein­tro­duced pop­u­la­tions face some spe­cific chal­lenges: “Our results show that these rein­tro­duced pop­u­la­tions usu­ally con­sist of too few indi­vid­u­als to be self-​sustaining. Small pop­u­la­tions are highly vul­ner­a­ble to loss of genetic vari­a­tion because each indi­vid­ual rep­re­sents a high per­cent­age of the population’s gene pool”, explains Daniel Förster, geneti­cist at the IZW.

The pop­u­la­tion in the Bohemian-​Bavarian for­est was founded by intro­duc­ing 5 to 10 lynxes in the 1970s and later sup­ple­ment­ing them with 18 addi­tional indi­vid­u­als. The pop­u­la­tion in the Vosges-​Palatinian for­est was founded by 21 lynxes released between 1983 and 1993. From this already lim­ited num­ber of founders, only some indi­vid­u­als actu­ally pro­duced offspring.

Eurasian lynx dis­tri­b­u­tion and con­ser­va­tion sta­tus
Credit: Euro­pean Commission/​Environment/​Nature & Bio­di­ver­sity Con­ser­va­tion sta­tus of large car­ni­vores.

Study results
To assess the effect of the rein­tro­duc­tion on the genetic sta­tus of these two lynx pop­u­la­tions, the sci­en­tists com­pared their genetic diver­sity with those of nat­u­rally occur­ring lynx pop­u­la­tions in East­ern Europe. For this pur­pose they analysed mol­e­c­u­lar mark­ers in lynx DNA obtained from fae­cal, blood, and tis­sue samples.

The study showed that these two pop­u­la­tions dis­played very low genetic diver­sity in com­par­i­son with other Euro­pean lynx pop­u­la­tions, with far fewer genetic vari­ants present in the new pop­u­la­tions than in the nat­u­rally occur­ring pop­u­la­tions. A pre­vi­ous study on a rein­tro­duced lynx pop­u­la­tion in Slove­nia and Croa­tia already indi­cated that small rein­tro­duced pop­u­la­tions suf­fer from low genetic diver­sity. The cur­rent study now con­firms these find­ings and thus points towards a more gen­eral pat­tern: Small pop­u­la­tions are unlikely to sur­vive in the long term. Accord­ing to the authors of the study, it is well jus­ti­fied to clas­sify the Bohemian-​Bavarian pop­u­la­tion as “endan­gered” and the Vosges-​Palatinian pop­u­la­tion as “crit­i­cally endan­gered” as is cur­rently done by the IUCN Red List of Threat­ened Species™. Thus, suit­able mea­sures for their ‘genetic rein­force­ment’ and con­ser­va­tion need to be taken.

What to do?
Espe­cially for small pop­u­la­tions it is cru­cial that not a sin­gle indi­vid­ual dies before it has repro­duced — be it of nat­ural causes or poach­ing. “It is there­fore really impor­tant to reduce the ille­gal killing of lynx to estab­lish and main­tain a long-​term viable pop­u­la­tion” empha­sizes Förster. He and his col­leagues also advo­cate the rein­tro­duc­tion of more lynxes to directly strengthen the genetic vari­abil­ity of the pop­u­la­tions. Indi­rect con­ser­va­tion mea­sures such as set­ting up wildlife cor­ri­dors can fur­ther facil­i­tate the genetic exchange between neigh­bour­ing pop­u­la­tions and thus con­tribute to the strength­en­ing of the over­all lynx pop­u­la­tion as well.

Eurasian lynx with off­spring at Stock­holm Skansen Zoo, a pos­si­ble genetic source?

(Source: Leib­niz Insti­tute for Zoo and Wildlife Research press release, 19.05.2016)