Identifying a new phylogeographic population of Blyth’s Tragopan (Tragopan blythii) through multi-locus analyses

Geographically and morphologically distinct populations within a species are frequently the focus of conservation efforts, especially when the populations are evolutionarily significant units. Blyth’s Tragopan (Tragopan blythii) is a globally-threatened species confined to South and Southeast Asia. During our field surveys in western Myanmar, we discovered a distinct group of individuals that differed in their appearance relative to all other populations. We further examined the differences in their DNA sequence using three nuclear introns and three mitochondrial genes through phylogenetic analytical methods. Our results showed the population from Mount Kennedy, Chin Hills formed reciprocal monophyletic groups with the nominate subspecies from Mount Saramati, Sagaing Division. Species delimitation analyses further confirmed this differentiation. Geographical isolation by the intervening lowlands found between high elevation habitats may have been the main cause of their differentiation. Hence, we propose that the Mount Kennedy population be viewed as a distinct evolutionarily significant unit and be given special priority for conservation.

同一物种内兼具地理分化与形态分化的种群，常为保护工作的核心关注对象，尤其当此类种群属于进化显著单元（evolutionarily significant unit）时。布莱氏角雉（Tragopan blythii）是一种全球受胁物种，仅分布于南亚与东南亚地区。我们在缅甸西部开展野外调查期间，发现了一群形态特征显著区别于所有已知种群的个体。我们进一步采用系统发育分析方法，以3个核内含子与3个线粒体基因为分子标记，对该种群与其他种群的DNA序列差异进行了比较分析。研究结果显示，钦山肯尼迪山种群与实皆省萨拉马蒂山的指名亚种形成了相互单系群。物种界定分析进一步验证了该种群的分化地位。高海拔生境之间的低地阻隔所引发的地理隔离，可能是该种群分化的主要成因。据此，我们建议将肯尼迪山种群视为独立的进化显著单元，并赋予其优先保护的特殊地位。