For insects that develop inside discrete hosts, both host size and host quality constrain offspring growth, influencing the evolution of body size and life history traits. Using a two-generation common garden experiment, we quantified the contribution of maternal and rearing hosts to differences in growth and life history traits between populations of the seed-feeding beetle Stator limbatus that use a large-seeded host, Acacia greggii, and a small-seeded host, Pseudosamanea guachapele. Populations differed genetically for all traits when beetles were raised in a common garden. Contrary to expectations from the local adaptation hypothesis, beetles from all populations were larger, developed faster and had higher survivorship when reared on seeds of A. greggii (the larger host), irrespective of their native host. We observed two host plant-mediated maternal effects: offspring matured sooner, regardless of their rearing host, when their mothers were reared on P. guachapele (this was not caused by an effect of rearing host on egg size), and females laid larger eggs on P. guachapele. This is the first study to document plasticity by S. limbatus in response to P. guachapele, suggesting that plasticity is an ancestral trait in S. limbatus that likely plays an important role in diet expansion. Although differences between populations in growth and life history traits are likely adaptations to their host plants, host-associated maternal effects, partly mediated by maternal egg size plasticity, influence growth and life history traits and likely play an important role in the evolution of the breadth of S. limbatus' diet. More generally, phenotypic plasticity mediates the fitness consequences of using novel hosts, likely facilitating colonization of new hosts, but also buffering herbivores from selection post-colonization. Plasticity in response to novel versus normal hosts varied among our study populations such that disentangling the historical role of plasticity in mediating diet evolution requires the consideration of evolutionary history.
|Number of pages||12|
|State||Published - Nov 2006|
Bibliographical noteFunding Information:
Acknowledgments We thank Scott Carroll, María Gómez, Rick Karban, Jordi Moya-Laraño, Craig Stillwell and two anonymous reviewers for comments on earlier versions of this paper. We thank Craig Stillwell and Bill Wallin for help with the experiments and field collecting in Arizona, and thank Celestino Amarillo, Fidelia Suárez, Carlos Sarmiento-M, María A. Sar-miento-Amarillo, Adela Suárez and Wilson Yaya for help with field collecting in Colombia. Support for this study was provided by Grants 1568 and 620 from Fundación para la Promoción de la Investigación y la Teconología, Banco de la República, Colombia (to A. Amarillo-Suárez) and DEB 01-10754 from the National Science Foundation, USA (to C. W. Fox). All experiments comply with the laws of the USA. Colombian populations of S. limbatus were imported into and maintained in the USA under permit no. 59578 of the Animal and Plant Health Inspection Service of the USDA (to C.W. Fox).
- Body size
- Egg size
- Host size
- Insect-plant interactions
- Stator limbatus
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics