Ishak Heather D, Dumbacher John P, Anderson Nancy L, Keane John J, Valkiūnas Gediminas, Haig Susan M, Tell Lisa A, Sehgal Ravinder N M
Department of Biology, San Francisco State University, San Francisco, California, United States of America.
PLoS One. 2008 May 28;3(5):e2304. doi: 10.1371/journal.pone.0002304.
The three subspecies of Spotted Owl (Northern, Strix occidentalis caurina; California, S. o. occidentalis; and Mexican, S. o. lucida) are all threatened by habitat loss and range expansion of the Barred Owl (S. varia). An unaddressed threat is whether Barred Owls could be a source of novel strains of disease such as avian malaria (Plasmodium spp.) or other blood parasites potentially harmful for Spotted Owls. Although Barred Owls commonly harbor Plasmodium infections, these parasites have not been documented in the Spotted Owl. We screened 111 Spotted Owls, 44 Barred Owls, and 387 owls of nine other species for haemosporidian parasites (Leucocytozoon, Plasmodium, and Haemoproteus spp.). California Spotted Owls had the greatest number of simultaneous multi-species infections (44%). Additionally, sequencing results revealed that the Northern and California Spotted Owl subspecies together had the highest number of Leucocytozoon parasite lineages (n = 17) and unique lineages (n = 12). This high level of sequence diversity is significant because only one Leucocytozoon species (L. danilewskyi) has been accepted as valid among all owls, suggesting that L. danilewskyi is a cryptic species. Furthermore, a Plasmodium parasite was documented in a Northern Spotted Owl for the first time. West Coast Barred Owls had a lower prevalence of infection (15%) when compared to sympatric Spotted Owls (S. o. caurina 52%, S. o. occidentalis 79%) and Barred Owls from the historic range (61%). Consequently, Barred Owls on the West Coast may have a competitive advantage over the potentially immune compromised Spotted Owls.
斑点猫头鹰的三个亚种（北方亚种，即西方鸣角鸮指名亚种Strix occidentalis caurina；加利福尼亚亚种，即西方鸣角鸮西方亚种S. o. occidentalis；以及墨西哥亚种，即西方鸣角鸮墨西哥亚种S. o. lucida）均受到栖息地丧失和横斑林鸮（S. varia）分布范围扩张的威胁。一个尚未解决的威胁是，横斑林鸮是否可能成为新的疾病菌株的来源，比如禽疟原虫（疟原虫属Plasmodium spp.）或其他可能对斑点猫头鹰有害的血液寄生虫。虽然横斑林鸮通常携带疟原虫感染，但这些寄生虫尚未在斑点猫头鹰中被记录到。我们对111只斑点猫头鹰、44只横斑林鸮以及其他九个物种的387只猫头鹰进行了血孢子虫寄生虫（白细胞原虫属Leucocytozoon、疟原虫属和血变原虫属Haemoproteus spp.）的筛查。加利福尼亚斑点猫头鹰同时感染多种物种的比例最高（44%）。此外，测序结果显示，北方和加利福尼亚斑点猫头鹰亚种共同拥有的白细胞原虫寄生虫谱系数量最多（n = 17）以及独特谱系数量最多（n = 12）。这种高水平的序列多样性很重要，因为在所有猫头鹰中，只有一种白细胞原虫物种（达氏白细胞原虫L. danilewskyi）被认为是有效的，这表明达氏白细胞原虫是一个隐存种。此外，首次在一只北方斑点猫头鹰中记录到了一种疟原虫寄生虫。与同域分布的斑点猫头鹰（指名亚种感染率5块斑林鸮（S. o. caurina）为52%，西方亚种S. o. occidentalis为79%）以及历史分布范围内的横斑林鸮（感染率61%）相比，西海岸横斑林鸮的感染率较低（15%）。因此，西海岸的横斑林鸮相对于可能免疫功能受损的斑点猫头鹰可能具有竞争优势。 2%，西方亚种S. o. occidentalis为79%）以及历史分布范围内的横斑林鸮（感染率61%）相比，西海岸横斑林鸮的感染率较低（15%）。因此，西海岸的横斑林鸮相对于可能免疫功能受损的斑点猫头鹰可能具有竞争优势。
