一項新的對人類及黑猩猩進行的全基因組分析披露,，這兩個物種在數(shù)百萬年中同時擁有著某些相同的會導致多態(tài)性—— 即在同一物種中有著不同的物理形式——的突變組合。在此之前，在人與猿之間只確認了2種共有的多態(tài)性：主要組織相容性復合體或MHC的變體,，及作為不同血型基礎(chǔ)的ABO血型系統(tǒng)中的多態(tài)性,。Ellen Leffler及其同事對59個人及10個西非黑猩猩的全基因組序列進行了研究并確認了在這兩個物種中有125個區(qū)域含有類似的突變——它們中的大多數(shù)出現(xiàn)在基因組的非編碼區(qū)域,。據(jù)研究人員披露,，這些區(qū)域中有6個看來代表了自這兩個世系分開后仍然持續(xù)存在于這兩個物種中的多態(tài)性。這些新的發(fā)現(xiàn)提供了平衡選擇的證據(jù),，在這種選擇過程中,，某些在一個物種中的非顯性特質(zhì)卻仍然以高出顯性特質(zhì)的程度得到維持。這種現(xiàn)象常常會使某些多態(tài)性在進化的過程中得以保留,。（生物谷Bioon.com）
DOI: 10.1126/science.1234070
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PMID:
Multiple Instances of Ancient Balancing Selection Shared Between Humans and Chimpanzees
Ellen M. Leffler1,*,Ziyue Gao2,*, Susanne Pfeifer3,*, Laure Ségurel1,4,*, Adam Auton5, Oliver Venn5, Rory Bowden3,5, Ronald Bontrop6, Jeffrey D. Wall7, Guy Sella8,9, Peter Donnelly3,5, Gilean McVean3,5, Molly Przeworski1,4,9,
Instances in which natural selection maintains genetic variation in a population over millions of years are thought to be extremely rare. We conducted a genome-wide scan for long-lived balancing selection by looking for combinations of SNPs shared between humans and chimpanzees. In addition to the major histocompatibility complex (MHC), we identified 125 regions in which the same haplotypes are segregating in the two species, all but two of which are non-coding. In six cases, there is evidence for an ancestral polymorphism that persisted to the present in humans and chimpanzees. Regions with shared haplotypes are significantly enriched for membrane glycoproteins, and a similar trend is seen among shared coding polymorphisms. These findings indicate that ancient balancing selection has shaped human variation and point to genes involved in host-pathogen interactions as common targets.
