Pleistocene origins of chorusing diversity in Mediterranean bush-cricket populations (Ephippiger diurnus)

We studied the Pleistocene diversification of a relatively endemic Mediterranean insect (Ephippiger diurnus ; Orthoptera: Tettigoniidae) to understand how species with restricted range may nonetheless exhibit the complex phylogeography normally associated with broad distribution. A time-calibrated molecular phylogeny based on two mitochondrial genes showed that E. diurnus diverged into two major clades, distinguished largely be male song, before or early during the Pleistocene. Several subclades also diverged before the most recent glacial period. Data from 20 microsatellite loci indicated higher genetic diversity in populations along the Mediterranean coast in France, consistent with the hypothesis that glacial refuges were located there. ‘Isolation by distance’ accounts for much genetic differentiation between populations, but some adjacent populations are highly differentiated. A Bayesian approach defined genetically distinct clusters and assigned individuals to their most proba...

本研究针对一种较为特有的地中海昆虫——昼鸣刺螽（Ephippiger diurnus；直翅目（Orthoptera）：螽斯科（Tettigoniidae））的更新世（Pleistocene）物种分化展开探究，旨在解析分布范围受限的物种为何仍能呈现通常仅见于广布物种的复杂系统地理学（phylogeography）格局。基于两个线粒体基因（mitochondrial genes）构建的时间校准分子系统发育树（time-calibrated molecular phylogeny）显示，昼鸣刺螽在更新世之前或更新世早期分化为两个主要演化支（clade），二者的核心区分特征为雄性鸣唱特征。多个次级演化支同样在末次冰期之前发生分化。针对20个微卫星位点（microsatellite loci）的数据分析显示，法国地中海沿岸种群的遗传多样性更高，这与“该区域曾为冰期避难所”的假说相符。‘距离隔离（Isolation by distance）’机制解释了种群间多数的遗传分化现象，但部分相邻种群间却存在极高的遗传分化。采用贝叶斯（Bayesian）方法可界定出遗传上独立的类群，并将个体划归至其最可能归属的...