Differentiation and hybridization betweenQuercus crispulaandQ. dentata(Fagaceae): insights from morphological traits, amplified fragment length polymorphism markers, and leafminer composition

Abstract

Quercus crispula and Q. dentata (Fagaceae) are dominant members of cool-temperate forests of Japan and are assumed to hybridize in nature. To characterize and discriminate these two species and their hybrids, we carried out multivariate analysis using several morphological traits and principal coordinate analysis using molecular (amplified fragment length polymorphism [AFLP]) data. Further, we examined the composition of Phyllonorycter species (leafmining insects) on individuals from a mixed forest. Morphological traits and Phyllonorycter composition differ enough in these two oak species to be useful for identification of species and hybrids. AFLP data, however, are less informative because the degree of molecular differentiation between the two species is low. Nine out of 105 individuals from a mixed stand had intermediate morphologies according to the multivariate analysis, and eight out of the nine individuals had intermediate Phyllonorycter composition in either one or both of the two study years. These eight individuals were tentatively assigned as hybrids or backcross individuals, and the remaining individual with intermediate morphologies was assigned as Q. dentata according to its Phyllonorycter composition and the AFLP analysis.

Phylogeographic structure and late Quaternary population history of the Japanese oak Quercus mongolica var. crispula and related species revealed by chloroplast DNA variation

“…Natural hybrids between Q. mongolica var. crispula and Q. dentata were also reported by Ishida et al (2003). Thus, it is thought that an occasional natural hybridization among the 4 species found in sympatric habitats leads to cpDNA introgression.…”

Microsatellite markers derived from Quercus mongolica var. crispula (Fagaceae) inner bark expressed sequence tags

“…Therefore, EST-SSR markers are likely to be especially useful in analyses of genetic diversity in populations in hybrid zones (where simultaneous analyses of hybridizing species are required) or at the distributional margins of species (where null alleles are likely to be present) since the frequency of null alleles is likely to be lower for EST-SSR markers, due to their conservative nature, than the corresponding frequencies of other types of markers that could be used. Ishida et al (2003) detected hybrid individuals between Q. mongolica and Q. dentata in a natural population, using morphological and AFLP data. In such a situation, EST-SSR markers developed in the present study should be useful for analyzing gene flow between species.…”

Oak canopy arthropod communities: which factors shape its structure?

“…There are few studies in oaks belonging to other groups (Southwood et al 2004(Southwood et al , 2005Nazemi et al 2008). The works mentioned above included species belonging to different geographic regions (i.e., Africa Southwood et al 1982), America (Preszler and Boecklen 1994;Forkner et al 2004;Yarnes et al 2008;Tovar-Sánchez et al 2013), Asia (Ishida et al 2003;Ito and Ozaki 2005;Nakamura et al 2008), and Europe (Southwood et al 2004(Southwood et al , 2005Sobek et al 2008)]. In general, these studies have revealed a great diversity of canopy arthropods (including epiphytes and suspended soil), a pattern that suggests that oaks are important habitats for these organisms.…”