Low levels of hybridization between domestic and wild Mallards wintering in the lower Mississippi Flyway
Low levels of hybridization between domestic and wild Mallards wintering in the lower Mississippi Flyway
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DOI：
10.1093/ornithology/ukac034
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发表时间：
2022-08-01
期刊：
影响因子：
2.3
通讯作者：
Lavretsky, Philip
中科院分区：
文献类型：
--
作者：
Davis, J. Brian;Outlaw, Diana C.;Lavretsky, Philip
绿头鸭（Anas platyrhynchos）鸭是一种在北美普遍存在的重要的社会经济猎禽。尽管大陆中部地区的绿头鸭数量普遍丰富，但北美东部的绿头鸭数量正在下降，部分原因可能是与人类放养的家养野鸭进行了广泛的杂交。本文研究了绿头鸭在密西西比中下游的主要越冬区的遗传组成。研究发现，近30%的野生绿头鸭携带来自北美家养绿头鸭的线粒体（mtDNA）单倍型，表明这些个体过去曾有过雌性野场绿头鸭的血统；然而，核结果只确定了4%的相同样本是假定的杂交种。恢复30%的旧世界（OW） A mtDNA单倍型的样本与整个密西西比飞行路线的总体趋势一致，并且这个百分比在我们间隔十年采样的绿头鸭中是稳定的。OW A mtDNA单倍型的捕获和延续可能是由于雌性的繁殖结构，而核信号的逆转回到野生祖先是由于连续的回交和与农场野鸭的低和/或减少的混合。未来对密西西比飞道绿头鸭野生祖先的研究将受益于跨飞道、季节和年份的分子和空间耦合技术，以寻找具有不同遗传祖先的绿头鸭种群的潜在转变，以及遗传祖先是否以某种方式与个体的出生和随后的繁殖地点有关。绿头鸭在世界范围内很常见，但在北美东部的大西洋飞行路线上数量正在减少，这种减少可能是由于野生绿头鸭和被放归狩猎的家养野禽之间广泛杂交的影响。我们用猎获的鸟类来调查可能的向西扩张和密西西比下游飞行路线的杂交率。尽管恢复了30%的含有野鸭线粒体DNA的样本，但只有4%的样本被确定为数千个核位点的杂交品种。在间隔十年取样的野鸭中，野鸭线粒体单倍型的流行率是一致的，这表明线粒体渗入可以被捕获并在世系中持续存在的时间远远超过核DNA。与大西洋迁徙路线相比，在密西西比河下游地区，野生野味农场的野鸭杂交品种的流行率要低得多，因此需要继续进行遗传监测，并制定管理策略来减少未来的杂交。
The Mallard (Anas platyrhynchos) duck is a ubiquitous and socio-economically important game bird in North America. Despite their generally abundant midcontinent population, Mallards in eastern North America are declining, which may be partially explained by extensive hybridization with human-released domestically derived game-farm Mallards. We investigated the genetic composition of Mallards in the middle and lower Mississippi flyway, key wintering regions for the species. We found that nearly 30% of wild Mallards carried mitochondrial (mtDNA) haplotypes derived from domestic Mallards present in North America, indicating that the individuals had female game-farm Mallard lineage in their past; however, nuclear results identified only 4% of the same sample set as putative hybrids. Recovering 30% of samples with Old World (OW) A mtDNA haplotypes is concordant with general trends across the Mississippi flyway and this percentage was stable across Mallards we sampled a decade apart. The capture and perpetuation of OW A mtDNA haplotypes are likely due to female breeding structure, whereas reversal of the nuclear signal back to wild ancestry is due to sequential backcrossing and lower and/or declining admixture with game-farm Mallards. Future studies of wild ancestry of Mississippi flyway Mallards will benefit from coupling molecular and spatial technology across flyways, seasons, and years to search for potential transitions of Mallard populations with different genetic ancestry, and whether the genetic ancestry is somehow linked to an individual's natal and subsequent breeding location.Lay Summary center dot Mallard ducks are common worldwide but are declining in the Atlantic flyway of eastern North America, a decline that may be influenced by widespread hybridization between genetically wild Mallards and domestic game-farm birds that are released for hunting. center dot We used hunter-harvested birds to investigate possible westward expansion and hybridization rates in the lower Mississippi flyway. center dot Despite recovering 30% of samples possessing game-farm Mallard-derived mitochondrial DNA, only 4% were identified as hybrids across thousands of nuclear loci. center dot Prevalence of game-farm Mallard-derived mitochondrial haplotypes were consistent in Mallards sampled a decade apart, suggesting mitochondrial introgression can be captured and persist within lineages far longer than nuclear DNA. center dot Whereas the prevalence of wild x game-farm Mallard hybrids remains significantly less in the lower Mississippi relative to the Atlantic flyway, continued genetic monitoring and development of management strategies to abate future hybridization will be required.