Australian Centre for Ancient DNA, The University of Adelaide, Adelaide, SA 5005, Australia;
Australian Centre for Ancient DNA, The University of Adelaide, Adelaide, SA 5005, Australia.
Proc Natl Acad Sci U S A. 2019 Sep 17;116(38):19019-19024. doi: 10.1073/pnas.1903275116. Epub 2019 Sep 3.
A recent study of mammoth subfossil remains has demonstrated the potential of using relatively low-coverage high-throughput DNA sequencing to genetically sex specimens, revealing a strong male-biased sex ratio [P. Pečnerová et al., 27, 3505-3510.e3 (2017)]. Similar patterns were predicted for steppe bison, based on their analogous female herd-based structure. We genetically sexed subfossil remains of 186 Holarctic bison ( spp.), and also 91 brown bears (), which are not female herd-based, and found that ∼75% of both groups were male, very close to the ratio observed in mammoths (72%). This large deviation from a 1:1 ratio was unexpected, but we found no evidence for sex differences with respect to DNA preservation, sample age, material type, or overall spatial distribution. We further examined ratios of male and female specimens from 4 large museum mammal collections and found a strong male bias, observable in almost all mammalian orders. We suggest that, in mammals at least, 1) wider male geographic ranges can lead to considerably increased chances of detection in fossil studies, and 2) sexual dimorphic behavior or appearance can facilitate a considerable sex bias in fossil and modern collections, on a previously unacknowledged scale. This finding has major implications for a wide range of studies of fossil and museum material.
最近一项对猛犸象亚化石遗骸的研究表明，使用相对低覆盖率高通量 DNA 测序技术对标本进行基因性别鉴定具有潜力，该技术揭示了强烈的雄性偏性性别比[P. Pečnerová 等人，27，3505-3510.e3（2017）]。基于类似的雌性基于群体的结构，预测草原野牛也存在类似的模式。我们对 186 头北温带野牛（ spp.）的亚化石遗骸进行了基因性别鉴定，还对 91 头棕熊（）进行了基因性别鉴定，这些棕熊不是基于雌性群体，结果发现这两组的雄性比例约为 75%，与猛犸象的观察比例（72%）非常接近。这种与 1:1 比例的巨大偏差出乎意料，但我们没有发现与 DNA 保存、样本年龄、材料类型或整体空间分布有关的性别差异的证据。我们进一步检查了 4 个大型博物馆哺乳动物收藏中的雄性和雌性标本比例，发现存在强烈的雄性偏性，几乎在所有哺乳动物目中都可以观察到这种偏性。我们认为，至少在哺乳动物中，1）更广泛的雄性地理范围可以大大增加在化石研究中被发现的机会，2）性别二态性行为或外观可以在化石和现代收藏中造成相当大的性别偏差，这种偏差的规模以前未被认识到。这一发现对广泛的化石和博物馆材料研究具有重大意义。
