Kerdelhué C, Magnoux E, Lieutier F, Roques A, Rousselet J
INRA, Centre de Bordeaux-Pierroton, UMR BIOGECO, Equipe Entomologie et Biodiversité, 69 route d'Arcachon, F-33612 Cestas cedex, France.
Heredity (Edinb). 2006 Jul;97(1):38-45. doi: 10.1038/sj.hdy.6800836. Epub 2006 May 10.
A parallel study of the genetic structure of two oligophagous species associated with the same hosts was conducted to determine the main factors shaping the distribution of genetic diversity. The bark beetle Tomicus piniperda and the pine processionary moth (PPM) Thaumetopoea pityocampa are both associated with the genus Pinus and belong to different guilds (xylophagous vs defoliating species). The PPM is an ectophagous species that feeds on the needles of living trees, whereas T. piniperda is endophagous and bores galleries in the inner bark of weakened trees. Both species were sampled in the main regions of France, and their genetic structure was assessed after genotyping with five microsatellite markers. Populations of the PPM were significantly structured. A pattern of isolation by distance was found when distances were calculated as bypassing the Massif Central, whereas no such pattern could be found with raw geographic distances. On the contrary, most populations of T. piniperda were not differentiated. No effect of host species could be detected in either of the two species. We conclude that the two taxa have contrasting effective dispersal rates per generation, and we hypothesize that this reflects the different selection pressures acting on individual fitness via different strategies of host use.
为了确定影响遗传多样性分布的主要因素，对与相同寄主相关的两种寡食性物种的遗传结构进行了平行研究。树皮甲虫松墨天牛（Tomicus piniperda）和松异舟蛾（PPM）（Thaumetopoea pityocampa）都与松属相关，且属于不同的食性类群（蛀木性与食叶性物种）。松异舟蛾是一种外食性物种，以活树的针叶为食，而松墨天牛是内食性的，在衰弱树木的内皮中蛀孔。这两个物种均在法国的主要地区进行采样，并在用五个微卫星标记进行基因分型后评估其遗传结构。松异舟蛾的种群有显著的结构。当以绕过中央高原的距离计算时，发现了距离隔离模式，而以原始地理距离计算时则未发现这种模式。相反，大多数松墨天牛种群没有分化。在这两个物种中均未检测到寄主物种的影响。我们得出结论，这两个分类单元每代的有效扩散率不同，并且我们推测这反映了通过不同的寄主利用策略对个体适合度施加的不同选择压力。
