Assessment of genetic and morphological differentiation among populations of the Diederik Cuckoo <i>Chrysococcyx caprius</i>
收藏资源简介：
The Diederik Cuckoo <i>Chrysococcyx caprius</i> is an African species widely distributed south of the Sahara, which migrates seasonally between breeding and nonbreeding sites. It is currently unknown whether the species consists of a single panmictic population or if it is genetically structured. To investigate this, we analysed sequence variation in three mitochondrial and two nuclear gene regions in combination with morphological measurements in specimens from four localities. Phylogenetic relationships were estimated using maximum-likelihood methods and included samples of Klaas’s Cuckoo <i>Chrysococcyx klaas</i>, Red-chested Cuckoo <i>Cuculus solitarius</i>, and African Cuckoo <i>Cuculus gularis</i>. Haplotype networks and analysis of molecular variance were used to characterise the spatial distribution of genetic diversity. A principal component analysis was performed to investigate morphological variation among localities. Molecular analysis identified two divergent mitochondrial lineages, which were found to occur in sympatry in one South African locality (Limpopo Province). The magnitude of divergence between versus within these lineages was low (0.4–1%) yet significant (<i>F</i><sub>ST</sub>: 0.84–0.88). Lack of apparent phylogeographic structure provides support for the absence of physical barriers to gene flow in this species. The divergent mitochondrial lineages did not differ in morphological measurements. The emergence and persistence of shallow mitochondrial divergence among sympatric lineages in the Diederik Cuckoo could be linked to maternal divergence in host selection of these brood parasites — a hypothesis requiring additional data to be tested.
狄氏杜鹃（Diederik Cuckoo，学名*Chrysococcyx caprius*）是一种广泛分布于撒哈拉以南非洲的鸟类，会在繁殖地与非繁殖地之间进行季节性迁徙。目前尚不清楚该物种究竟仅包含一个随机交配种群（panmictic population），还是存在遗传结构分化。为探究这一问题，本研究对采自4个采样点的标本，分析了3个线粒体基因与2个核基因区域的序列变异，并整合形态测量数据进行分析。本研究采用最大似然法（maximum-likelihood）构建系统发育关系，分析样本涵盖克氏金鹃（Klaas’s Cuckoo，*Chrysococcyx klaas*）、红胸杜鹃（Red-chested Cuckoo，*Cuculus solitarius*）与非洲杜鹃（African Cuckoo，*Cuculus gularis*）的标本。本研究借助单倍型网络与分子方差分析（analysis of molecular variance），阐明了遗传多样性的空间分布特征；同时通过主成分分析（principal component analysis）探究了不同采样点间的形态变异情况。分子分析结果鉴定出两个分化的线粒体谱系，且二者在南非林波波省（Limpopo Province）这一采样点呈同域分布（sympatry）。这些谱系间的分化程度较低（0.4%~1%），但分化结果具有统计学显著性（遗传分化系数<sub>F</sub><sub>ST</sub>：0.84~0.88）。未检测到明显的系统地理结构，这表明该物种不存在阻碍基因交流的物理屏障。上述分化的线粒体谱系在形态测量指标上并无显著差异。狄氏杜鹃同域谱系间存在的浅层线粒体分化现象，可能与这些巢寄生鸟类（brood parasites）的宿主选择母系分化有关——这一假说仍需更多数据加以验证。
