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Evo­lu­tion


A Col­lec­tion of News by Moos


201623Dec22:16

Two closely related felids evolved very dif­fer­ently due to cli­mate change

Infor­ma­tion
pub­lished 23 Decem­ber 2016 | mod­i­fied 23 Decem­ber 2016
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Asian golden catSouth­east Asia is home to numer­ous felids, includ­ing the Asian golden cat and the Bor­neo bay cat. The two cat species are closely related sis­ter species which split from each other 3.16 mil­lion years ago. Yet, their more recent his­tory was quite dif­fer­ent. Sci­en­tists from the Leib­niz Insti­tute for Zoo and Wildlife Research (Leibniz-​IZW) and their inter­na­tional part­ners could now show that, after a mas­sive vol­canic erup­tion about 73,000 years ago, the Asian golden cat sur­vived only in Indochina, from where it expanded its range in dra­matic fash­ion dur­ing the peak of the last Ice Age. The cooler and drier cli­mates at the time pushed its sis­ter species, the Bor­neo bay cat, how­ever, into rain­for­est refuges on Bor­neo. These find­ings are pub­lished on 19 Octo­ber in the sci­en­tific jour­nal Royal Soci­ety Open Sci­ence.

Today, the endan­gered Bor­neo bay cat only occurs in ever­green rain­forests on Bor­neo. In con­trast, the Asian golden cat occurs in habi­tats rang­ing from trop­i­cal rain­forests on Suma­tra to tem­per­ate forests in the Himalayas and south­ern China. Liv­ing in dif­fer­ent envi­ron­ments resulted in the evo­lu­tion of dif­fer­ent colour morphs for the Asian golden cat, such as spot­ted, red­dish and grey­ish to black. Aided by this vari­a­tion in colour morphs, up to five sub­species have been recog­nised in the Asian golden cat. A com­pre­hen­sive tax­o­nomic assess­ment, where mol­e­c­u­lar data and mor­pho­log­i­cal char­ac­ters are com­bined, was still lack­ing for both species, and it was unclear why the two sis­ter species dif­fered so much in their range and distribution.

Asian golden cat and Borneo bay cat distributionPro­jected dis­tri­b­u­tion of the Asian golden cat (a – e) and the bay cat (f – j) along a time axis from 120 kya until present: (a,f) for the Late Pleis­tocene (approx. 120 kya) using the LGM pro­jec­tions; (b,g) the thick­ness of the Young Toba Tuffs (YTT) was super­im­posed on the pro­jec­tion to indi­cate the sever­ity of impact of the Toba super vol­canic erup­tion approx­i­mately 74 kya; (c,h) the Last Glacial Max­i­mum (approx. 22 kya); (d,i) the mid Holocene (approx. 6 kya) and (e,j) the cur­rent dis­tri­b­u­tion accord­ing to the IUCN Red List of Threat­ened Species used for the mod­el­ling (hatched pat­tern), while areas out­side of the cur­rent dis­tri­b­u­tion were shaded in light blue.
Patel et al., 2016. Two species of South­east Asian cats in the genus Catop­uma with diverg­ing his­to­ries: an island endemic for­est spe­cial­ist and a wide­spread habi­tat gen­er­al­ist in Royal Soci­ety Open Sci­ence.
Cre­ative Com­mons (CC BY 4.0)

Bay catAn inter­na­tional team of researchers from the Leibniz-​IZW, National Muse­ums Scot­land and WWF-​Malaysia set out to pro­vide such an assess­ment by using sam­ples col­lected mostly from museum spec­i­mens and apply­ing a new approach where they com­bined mol­e­c­u­lar and mor­pho­log­i­cal analy­ses with sta­tis­ti­cal mod­els of Pleis­tocene species dis­tri­b­u­tions. The results sug­gest diver­gent evo­lu­tion­ary his­to­ries for the two sis­ter cat species. Dur­ing the Late Pleis­tocene and espe­cially towards the end of the last Ice Age, the bay cat became restricted to rain­for­est refuges on Bor­neo. The results of the mod­els for the Asian golden cat, how­ever, showed that through­out the same period large parts of South­east Asia con­tained suit­able habi­tat. “Although we expected this on the basis of their cur­rent dis­tri­b­u­tion, our mol­e­c­u­lar find­ings first appeared to con­tra­dict these results.” says Rid­dhi P. Patel, PhD stu­dent at the Leibniz-​IZW. The sci­en­tist found a very low mol­e­c­u­lar diver­sity in Asian golden cats, which seemed very sur­pris­ing and at vari­ance in view of the large dis­tri­b­u­tion area. The res­o­lu­tion of this para­dox is pro­vided by assum­ing a dra­matic pop­u­la­tion reduc­tion dur­ing the Late Pleis­tocene. “We think that the Toba super-​volcanic erup­tion on Suma­tra, about 73,000 years ago, destroyed so much for­est habi­tat that it caused a mas­sive pop­u­la­tion decline in most of the range of the Asian golden cat, with pop­u­la­tions sur­viv­ing only in Indochina. Only a long time after suit­able cli­matic con­di­tions returned dur­ing the last Ice Age were Asian golden cats able to move out from their Indochi­nese refuge and return to for­mer habi­tats, spread­ing north to south­ern China, east to India and, in par­tic­u­lar, south to Suma­tra”, Patel explains. This hypoth­e­sis was con­sis­tent with data for mor­pho­log­i­cal char­ac­ters. “We found the great­est diver­sity in coat colour morphs in Indochina, whereas on the Malay Penin­sula and in Suma­tra golden cats are almost exclu­sively red­dish,” adds Andrew C. Kitch­ener of the National Museum of Scotland.

These results show that despite their close rela­tion­ship, the Asian golden cat and Bor­neo bay cat responded quite dif­fer­ently to cli­mate change dur­ing the late Ice Age. The recent rapid expan­sion of the range of the Asian golden cat clearly is incom­pat­i­ble with the cur­rent tax­o­nomic clas­si­fi­ca­tion into five sub­species. “We rec­om­mend recog­nis­ing only two Asian golden cat sub­species, one north of the Isth­mus of Kra and the other one south of it on the Malay Penin­sula and in Suma­tra,” says Patel.

(Source: Leibniz-​IZW press release, 22.12.2016)


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Tiger range countries map

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

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