スプートニク日本
オーストラリア・シドニー大学のレベッカ・ジョンソン兼任教授は、「このゲノム研究は、コアラ救済の出発点となる。私たちはこの研究から、コアラのユニークな食生活に関連した遺伝子の数多くの独特な特徴にとどまらず、免疫力の仕組みや遺伝的多様性の高さ、コアラが自然界に生まれてきた過程を明らかにすることができた」と述べた。
かつて、コアラはとてもたくさん生息していた。１千万匹を超えていたとの記録もある。しかし、近年では絶滅の危機に瀕するまで激減し、その謎の解明が迫られていた。
コアラ激減の原因は、現在、研究者らの間で熱い論争のテーマのままとなっている。一部の学者らが、クラミジア感染症やそれと関連した不妊症との関わりを指摘する一方、気候変動や森林伐採、他の自然環境の変動を挙げる研究者もいる。ジョンソン兼任教授と「コアラゲノム・コンソーシアム」の同僚たちは、長い間、この謎の解明に取り組んできた。オーストラリア全土の生息域からコアラのデオキシリボ核酸のサンプルを集め、解読と比較を繰り返し行ってきた。
興味深いことに、オーストラリアの様々な地域から採取したコアラのゲノムを比較すると、彼らの絶滅については、考えられているほど人間の関与は強くなく、４万年前まではコアラの個体数は現在の数百倍多かったということも見えてきた。それとほぼ同時期、オーストラリア大陸の気候は、明らかにそれまでより高温になり、コアラに限らず、事実上全ての有袋類の動物の激減が生じていた。
集められた遺伝子情報の研究が、コアラの絶滅を食い止めるだけでなく、クラミジア感染症やコアラレトロウィルス、北部オーストラリアでますます多くが発症しているコアラ特有のエイズといった病気からこの希少な動物を救うことができるようになることを、研究者らは望んでいる。
Koala.
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© AP Photo / Wong Maye-E
A koala feeds on eucalyptus leaves in its new enclosure at the Singapore Zoo, Wednesday, May 20, 2015, in Singapore. Four koalas originating from Brisbane's Lone Pine Koala Sanctuary, will stay at the Singapore Zoo until January 2016 before returning to Australia. The Singapore Zoo is also known for its efforts in promoting and educating the public about the importance of wildlife conservation through its educational programs and through the breeding of endangered species in captivity. Koalas are considered 'vulnerable' and are threatened by habitat loss and encroachment.
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© AP Photo / Frank Augstein
The yet unnamed male koala baby clings at the back of its mother Iona, at the Zoo in Duisburg, western Germany on Wednesday March 27, 2013. The little Koala left the mothers pouch after six months for the first time and is one of two newborn babies. The Duisburg Zoo is one of the major breeding units for Koalas in Europe. (AP Photo/Frank Augstein)
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© AP Photo / Wong Maye-E
A koala feeds on eucalyptus leaves in its new enclosure at the Singapore Zoo, Wednesday, May 20, 2015, in Singapore. Four koalas originating from Brisbane's Lone Pine Koala Sanctuary, will stay at the Singapore Zoo until January 2016 before returning to Australia. The Singapore Zoo is also known for its efforts in promoting and educating the public about the importance of wildlife conservation through its educational programs and through the breeding of endangered species in captivity. Koalas are considered 'vulnerable' and are threatened by habitat loss and encroachment.
Koala.
2/4
© AP Photo / Wong Maye-E
A koala feeds on eucalyptus leaves in its new enclosure at the Singapore Zoo, Wednesday, May 20, 2015, in Singapore. Four koalas originating from Brisbane's Lone Pine Koala Sanctuary, will stay at the Singapore Zoo until January 2016 before returning to Australia. The Singapore Zoo is also known for its efforts in promoting and educating the public about the importance of wildlife conservation through its educational programs and through the breeding of endangered species in captivity. Koalas are considered 'vulnerable' and are threatened by habitat loss and encroachment.
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© AP Photo / Frank Augstein
The yet unnamed male koala baby clings at the back of its mother Iona, at the Zoo in Duisburg, western Germany on Wednesday March 27, 2013. The little Koala left the mothers pouch after six months for the first time and is one of two newborn babies. The Duisburg Zoo is one of the major breeding units for Koalas in Europe. (AP Photo/Frank Augstein)
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© AP Photo / Wong Maye-E
A koala feeds on eucalyptus leaves in its new enclosure at the Singapore Zoo, Wednesday, May 20, 2015, in Singapore. Four koalas originating from Brisbane's Lone Pine Koala Sanctuary, will stay at the Singapore Zoo until January 2016 before returning to Australia. The Singapore Zoo is also known for its efforts in promoting and educating the public about the importance of wildlife conservation through its educational programs and through the breeding of endangered species in captivity. Koalas are considered 'vulnerable' and are threatened by habitat loss and encroachment.
