Departamento de Botánica, Universidad de Concepción, Concepción, Chile.
PLoS One. 2013;8(1):e53892. doi: 10.1371/journal.pone.0053892. Epub 2013 Jan 11.
Spatial variation in host plant availability may lead to specialization in host use and local host adaptation in herbivorous insects, which may involve a cost in performance on other hosts. We studied two geographically separated populations of the seed beetle Megacerus eulophus (Coleoptera: Bruchidae) in central Chile: a population from the host Convolvulus chilensis (in Aucó) and a population from C. bonariensis (in Algarrobo). In Aucó C. chilensis is the only host plant, while in Algarrobo both C. bonariensis and C. chilensis are available. We tested local adaptation to these native host plants and its influence on the use of another, exotic host plant. We hypothesized that local adaptation would be verified, particularly for the one-host population (Aucó), and that the Aucó population would be less able to use an alternative, high-quality host. We found evidence of local adaptation in the population from C. chilensis. Thus, when reared on C. chilensis, adults from the C. chilensis population were larger and lived longer than individuals from the C. bonariensis population, while bruchids from the two populations had the same body size and longevity when reared on C. bonariensis. Overall, bruchids from the C. chilensis population showed greater performance traits than those from the C. bonariensis population. There were no differences between the bruchid populations in their ability to use the alternative, exotic host Calystegia sepium, as shown by body size and longevity patterns. Results suggest that differences in local adaptation might be explained by differential host availability in the study populations.
生境中寄主植物的分布变化可能导致植食性昆虫对寄主的特化和局部适应，这可能会导致其在其他寄主上的表现能力下降。我们研究了智利中部两个地理位置分离的麦秆象甲种群：一个种群来自旋花属植物智利旋花（在奥科），另一个种群来自 C. bonariensis（在阿尔加罗沃）。在奥科，智利旋花是唯一的寄主植物，而在阿尔加罗沃，C. bonariensis 和 C. chilensis 都有。我们测试了对这些本地寄主植物的局部适应及其对另一种外来寄主植物的利用的影响。我们假设会发现局部适应的证据，特别是在单宿主种群（奥科）中，并且奥科种群将更难利用替代的高质量宿主。我们在智利旋花种群中发现了局部适应的证据。因此，当在智利旋花上饲养时，来自智利旋花种群的成虫比来自 C. bonariensis 种群的成虫更大、寿命更长，而来自两个种群的象甲在饲养在 C. bonariensis 上时具有相同的体型和寿命。总体而言，智利旋花种群的象甲表现出比 C. bonariensis 种群更好的性能特征。象甲种群在利用替代的外来寄主植物旋花 Calystegia sepium 的能力上没有差异，这体现在体型和寿命模式上。结果表明，局部适应的差异可能是由研究种群中寄主可用性的差异解释的。
