Moos’ Blog

Bio­di­ver­sity Counts!
Obser­va­tions and opin­ions con­cern­ing zoos, evo­lu­tion, nature con­ser­va­tion and the way we treat/​support the ecosys­tems which are sup­posed to serve us.


Genetic source for re-​introduction of wild tigers in Kaza­khstan too small?

pub­lished 25 Decem­ber 2011 | mod­i­fied 18 Decem­ber 2016

In April this year, 2011, we were pleas­antly sur­prised by a plan that was launched by the Kaza­khstan gov­ern­ment to rein­tro­duce wild tigers in part of the coun­try where the species went extinct in the last cen­tury. A unique tiger nature reserve will be estab­lished, accord­ing Prime Min­is­ter Masi­mov, in the south­ern part of the Lake Balkhash area, the orig­i­nal habi­tat of the Turan tiger, or Caspian tiger (Pan­thera tigris vir­gata). The Caspian tiger, which once ranged through­out the humid forests, man­groves and grass­lands of Afghanistan, Turkey, Mon­go­lia, Iran, North­ern Iraq, Azer­baizhan, Turk­menistan, Uzbek­istan and the Cen­tral Asian areas of Rus­sia, was offi­cially declared extinct in 1979, but last sight­ings have been in the 1950s. The plan’s objec­tive is to relo­cate Amur tigers, aka Siber­ian tigers, from the Russ­ian Far East to suit­able habi­tat in Kaza­khstan. Research con­ducted in 2010 showed that the delta of the Ili River with its wet­lands of lakes, marshes and thick­ets, pro­vides this suit­able tiger habi­tat. The Ili River flows into Lake Balkhash, Cen­tral Asia’s second-​largest lake.

Lake Balhash basinmap source: Wikipedia

The plan is one of the results of the ambi­tious Global Tiger Recov­ery Pro­gram that intends to dou­ble the num­ber of wild tigers by 2022. This means that in ten years time the wild tiger num­bers should increase from an esti­mated 3,200 to about 7,000 across the 13 tiger range countries.

Why Amur tiger ?

Recent research find­ings iden­ti­fied the Caspian tiger as genet­i­cally sim­i­lar to liv­ing Amur tigers. This makes the Amur tiger (Pan­thera tigris altaica) the appro­pri­ate tiger sub­species as genetic source to use for rein­tro­duc­tion and repop­u­late the Lake Balkhash area. Although the extinc­tion of the Caspian (Turan) tiger was due to poach­ing and habi­tat loss at the time, the area still retains suit­able habi­tat, as stated before, and equally impor­tant it retains tiger’s tra­di­tional prey ani­mals, such as ripar­ian deer, Per­sian gazelles and wild hogs. There­fore WWF-​Russia expect that tigers can again roam the forests and land­scapes of Cen­tral Asia.

Pop­u­la­tion viability ?

In a recently pub­lished arti­cle it is shown that the effec­tive pop­u­la­tion of Amur tiger is fewer than 14 ani­mals. So, how viable will the pop­u­la­tion of Amur tigers be? As it means that of the cur­rent pop­u­la­tion of about 500 Amur tigers the genetic diver­sity rep­re­sents not more than just 14 ani­mals. A very low genetic diver­sity like this makes the pop­u­la­tion vul­ner­a­ble to dis­ease and genetic dis­or­ders, as these will be eas­ily passed on to the next gen­er­a­tion. The sci­en­tists con­clude that this small genetic foun­da­tion is due to expand­ing human set­tle­ments, habi­tat loss and poach­ing in early 20th cen­tury, which almost drove the Amur tiger to extinc­tion. The few remain­ing breed­ing indi­vid­u­als, about 30, in the 1940s rep­re­sented only a very small gene pool. This resulted in a loss of genes, and the tiger pop­u­la­tion has not recov­ered since from this low vari­ety of genes.

A study which also looked at gene vari­ety in Amur tigers in cap­tiv­ity, e.g. zoos, found a sim­i­lar low vari­ety of genes, but gene vari­ants existed in cap­tive ani­mals which were lost in wild ani­mals. I can imag­ine that these genes come from tigers which have been caught in the early 20th cen­tury and their off­spring which have been kept in cap­tiv­ity since. Although the activ­i­ties of the ani­mal deal­ers in the begin­ning of the 20th cen­tury con­tributed to the cur­rent sit­u­a­tion where Amur tigers are threat­ened with extinc­tion, they per­haps now will con­tribute to their survival.

Isn’t the present sit­u­a­tion and Kazakhstan’s plan an ideal oppor­tu­nity to try and breed wild tigers with cap­tive tigers? As this will increase genetic vari­ety and there­fore could increase genetic resis­tance and sur­vival of Amur tigers in the wild. I do not know of many suc­cess­ful re-​introduction into the wild of cap­tive bred tigers, but try­ing to breed cap­tive male and wild female tigers could work, I guess. If the male tiger still is able and will­ing to cop­u­late with a wild female, and this tigress allows to be mounted by the male, their off­spring could be raised in the wild, I sup­pose. Per­haps it has been tried before. If not, it is worth a try!

Apart from the via­bil­ity of the poten­tial tiger pop­u­la­tion the via­bil­ity of the envi­ron­ment and its suit­abil­ity for tigers in the long run is impor­tant. So, the ques­tion is if the Kaza­khstan gov­ern­ment, sup­ported by Russ­ian gov­ern­ment, will be able to restore the Balkhash basin ecosys­tem and the water bal­ance of the Ili-​Balkhash basin. Since 1960, water lev­els in Lake Balkhash have been declin­ing, due to evap­o­ra­tion and increased water usage for irri­ga­tion along the Ili and Karatal Rivers. To sus­tain a wild tiger habi­tat effec­tively will not be easy, but at least a first effort is made to kick-​off what has been promised in St. Peters­burg. And “Efforts to grow the global tiger pop­u­la­tion will cer­tainly ben­e­fit from expand­ing the tiger’s exist­ing range,” accord­ing to the man­ager of Asian species con­ser­va­tion for WWF.

(Sources: Tiger Ter­ri­tory; the Sixth Extinc­tion web­site; ENS, 26.04.2011; BBC Earth News, 28.02.2011; Driscoll et al. 2009 in PLoS ONE; Rus­sello et al. 2004 in Con­ser­va­tion Genet­ics; Henry et al. 2009 in Mol­e­c­u­lar Ecol­ogy; Alasaad et al. 2011 in Mam­malian Biol­ogy)

Related blogs

Goal: 7000 tigers in the wild

Tiger range countries map

Tiger map” (CC BY 2.5) by Sander­son et al., 2006.

about zoos and their mis­sion regard­ing breed­ing endan­gered species, nature con­ser­va­tion, bio­di­ver­sity and edu­ca­tion, which of course relates to the evo­lu­tion of species.
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