墨西哥是吉娃娃的故鄉(xiāng),，而中國(guó)西藏則培育出了獅子狗,。然而一項(xiàng)最新的遺傳分析表明,，所有的小狗都起源于中東,。
狗的起源一直是進(jìn)化生物學(xué)上的熱點(diǎn)問(wèn)題?？茖W(xué)家認(rèn)同它們是由灰狼馴化而來(lái)的,，但對(duì)于這一切究竟發(fā)生在哪里卻各執(zhí)一詞。如今,，科學(xué)家通過(guò)對(duì)核子DNA的分析終于解開(kāi)了這個(gè)謎題,。研究人員發(fā)現(xiàn)，一個(gè)名為IGF1的基因在小狗中很普遍,，但在大型犬以及野狗中卻罕有發(fā)現(xiàn),。然而這一基因的一個(gè)非常類似的版本卻存在于中東地區(qū)的灰狼中。這意味著該地區(qū)可能就是全世界小狗的起源地,。研究人員在最新出版的《BMC生物學(xué)》雜志上報(bào)告了這一發(fā)現(xiàn)。（生物谷Bioon.com）
相關(guān)研究：
PNAS：建立全球幼犬祖先基因圖 揭示家狗的起源
MBE：狗的祖先是中國(guó)馴狼
生物谷推薦原始出處：
BMC Biology 2010, 8:16doi:10.1186/1741-7007-8-16
The IGF1 small dog haplotype is derived from Middle Eastern gray wolves
Melissa M. Gray , Nathan B. Sutter , Elaine A. Ostrander and Robert K. Wayne
Background
A selective sweep containing the insulin-like growth factor 1 (IGF1) gene is associated with size variation in domestic dogs. Intron 2 of IGF1 contains a SINE element and single nucleotide polymorphism (SNP) found in all small dog breeds that is almost entirely absent from large breeds. In this study, we surveyed a large sample of grey wolf populations to better understand the ancestral pattern of variation at IGF1 with a particular focus on the distribution of the small dog haplotype and its relationship to the origin of the dog.
Results
We present DNA sequence data that confirms the absence of the derived small SNP allele in the intron 2 region of IGF1 in a large sample of grey wolves and further establishes the absence of a small dog associated SINE element in all wild canids and most large dog breeds. Grey wolf haplotypes from the Middle East have higher nucleotide diversity suggesting an origin there. Additionally, PCA and phylogenetic analyses suggests a closer kinship of the small domestic dog IGF1 haplotype with those from Middle Eastern grey wolves.
Conclusions
The absence of both the SINE element and SNP allele in grey wolves suggests that the mutation for small body size post-dates the domestication of dogs. However, because all small dogs possess these diagnostic mutations, the mutations likely arose early in the history of domestic dogs. Our results show that the small dog haplotype is closely related to those in Middle Eastern wolves and is consistent with an ancient origin of the small dog haplotype there. Thus, in concordance with past archeological studies, our molecular analysis is consistent with the early evolution of small size in dogs from the Middle East.
