Evidence for Local Adaptation in Closely Adjacent Subpopulations of Northern Red Oak (Quercus rubra L.) Expressed as Resistance to Leaf Herbivores

Abstract

Many studies of herbaceous plant populations have illustrated the potential of adjacent subpopulations to adapt to local ecological conditions. However, the extent to which local adaptation on a small geographical scale can occur in outcrossing tree populations is not well understood. In this study, we reciprocally transplanted acorns from adjacent subpopulations of northern red oak (Quercus rubra L.) occupying north-, southwest-, and west-facing slopes within a 4-ha plot in a Missouri oak-hickory forest. The quantitative character we measured was leaf damage by herbivores on first-year seedlings, because it reflects resistance to insect herbivores-a quantitative trait that could be under different selective pressures in dissimilar microhabitats. We found that seedlings showed the least damage when planted at the site of the maternal plant. This finding provides initial but strong evidence of local adaptation and illustrates that selection associated with leaf harbivory may have a strong impact on the genetic structure of local tree populations. Such a result is unexpected for a widely outcrossing species on such a small geographical scale but indicates that genetic structuring is possible within other plant populations occupying heterogeneous environments.

Comparison of morphological characters and molecular markers for the analysis of hybridization in sessile and pedunculate oak

“…In northern red oak, Sork et al (1993) showed that genetic differentiation for insect resistance occurs over a short distance, in response to environmental heterogeneity in the distribution of insects. However, our experiment did not allow us to attribute the morphological differentiation to an environmental or genetic origin.…”

Local adaptation in host–parasite systems

“…Host and parasite performance may be influenced by epigenetic maternal or conditioning effects such as acquired immunity. Furthermore, parasites or hosts may perform better in their home site because they have adapted to their local environment rather than to their local hosts and parasites, respectively (Rice, 1983;Sork et al, 1993;Roy, 1998). Natural parasite populations may also have their own coevolving hyperparasites, so parasites may be locally adapted only in the absence of these hyperparasites (Mopper et al, 1995).…”

Fine-Scale Genetically Based Differentiation of Life-History Traits in the Perennial Shrub Lupinus Arboreus

“…In most instances, the relative fitness of plants often was greatest for progeny from that locality. Sork et al (1993) found evidence for local adaptation in Quercus rubra for resistance to folivores in spite of high levels of gene flow across microhabitats. However, other studies have detected no evidence for adaptation to microsites (Cheplick 1988;Rice and Mack 1991;.…”

“…Although these general issues have been addressed in many annual plant populations (Antonovics and Bradshaw 1970;Snaydon and Davies 1982), local adaptation and differentiation of adaptive traits in woody perennial plant populations has seldom been examined (but see Sork et al 1993), especially over relatively small spatial scales. Moreover, few studies examine genetic structure for more than one plant life-history stage (but see Tonsor et al 1993;Cabin 1996;Kalisz et al 2001).…”