Abstract：
Glandular trichomes are implicated in direct and indirect defense of plants. However, the degree to which glandular and non-glandular trichomes have evolved as a consequence of herbivory remains unclear, because their heritability, their association with herbivore resistance, their trade-offs with one another, and their association with other functions are rarely quantified.
We conducted a phylogenetic comparison of trichomes and herbivore resistance against the generalist caterpillar, Heliothis virescens, among tarweed species (Asteraceae: Madiinae) and a genetic correlation study comparing those same traits among maternal half-sibs of three tarweed species.
Within a tarweed species, we found no evidence that herbivore growth rate decreased on tarweed individuals or maternal sib groups with more glandularity or denser trichomes. However, tarweed species with more glandularity and fewer non-glandular trichomes resulted in slower-growing herbivores. Likewise, a trade-off between glandular and non-glandular trichomes was apparent among tarweed species, but not among individuals or sib groups within a species.
Our results suggest that this key herbivore does not select for trichomes as a direct defense in tarweed species. However, trichomes differed substantially among species and likely affect herbivore pressure on those species. Our results demonstrate that trade-offs among plant traits, as well as inference on the function of those traits, can depend on scale.
We conducted a phylogenetic comparison of trichomes and herbivore resistance against the generalist caterpillar, Heliothis virescens, among tarweed species (Asteraceae: Madiinae) and a genetic correlation study comparing those same traits among maternal half-sibs of three tarweed species.
Within a tarweed species, we found no evidence that herbivore growth rate decreased on tarweed individuals or maternal sib groups with more glandularity or denser trichomes. However, tarweed species with more glandularity and fewer non-glandular trichomes resulted in slower-growing herbivores. Likewise, a trade-off between glandular and non-glandular trichomes was apparent among tarweed species, but not among individuals or sib groups within a species.
Our results suggest that this key herbivore does not select for trichomes as a direct defense in tarweed species. However, trichomes differed substantially among species and likely affect herbivore pressure on those species. Our results demonstrate that trade-offs among plant traits, as well as inference on the function of those traits, can depend on scale.
摘要：
目的：腺毛与植物的直接和间接防御有关。然而,由于草食性，腺毛和非腺毛的进化程度尚不清楚，因为他们的遗传能力，它们与食草动物抗性的联系，他们之间的取舍，它们与其他功能的关联很少被量化。
方法：我们对毛虫和食草动物对通才毛虫的抗性进行了系统发育比较，Heliothisviresces，在tarweed物种（Asteraceae：Madiinae）之间进行遗传相关性研究，比较了三种tarweed物种的母体半同胞之间的相同性状。
结果：在一种tarweet物种中，我们没有发现草食动物的生长速率在有更多腺体或更密集的毛状体的tarweet个体或母体同胞组上下降的证据。然而,具有更多腺体和更少的非腺体毛状体的tarweet物种导致生长较慢的草食动物。同样，在tarweet物种中，腺毛和非腺毛之间的权衡很明显，但不是在一个物种内的个体或同胞群体之间。
结论：我们的结果表明，这种关键的草食动物没有选择毛状体作为tarweet物种的直接防御。然而,毛状体在物种之间差异很大，可能会影响食草动物对这些物种的压力。我们的结果表明，植物性状之间的权衡，以及对这些特征功能的推断，可以取决于规模。
方法：我们对毛虫和食草动物对通才毛虫的抗性进行了系统发育比较，Heliothisviresces，在tarweed物种（Asteraceae：Madiinae）之间进行遗传相关性研究，比较了三种tarweed物种的母体半同胞之间的相同性状。
结果：在一种tarweet物种中，我们没有发现草食动物的生长速率在有更多腺体或更密集的毛状体的tarweet个体或母体同胞组上下降的证据。然而,具有更多腺体和更少的非腺体毛状体的tarweet物种导致生长较慢的草食动物。同样，在tarweet物种中，腺毛和非腺毛之间的权衡很明显，但不是在一个物种内的个体或同胞群体之间。
结论：我们的结果表明，这种关键的草食动物没有选择毛状体作为tarweet物种的直接防御。然而,毛状体在物种之间差异很大，可能会影响食草动物对这些物种的压力。我们的结果表明，植物性状之间的权衡，以及对这些特征功能的推断，可以取决于规模。
