Differentiation of three closely related Japanese oak species and detection of interspecific hybrids using AFLP markers

Abstract

Three white-oak species ( Quercus crispula Blume, Quercus dentata Thunb., and Quercus serrata Thunb.) are native, widely distributed, and prominent species in the temperate deciduous forests of Japan. They are closely related to each other and overlapping morphological variation in some traits is observed, although they differ from each other in appearance. To distinguish these species genetically, we carried out clustering analysis based on Bayesian approach by AFLP markers using morphologically typical trees. Although no completely species-specific markers were obtained, these species could be distinguished and their genetic relationships were evaluated based on differences in frequencies of 66 polymorphic markers, including four that were almost completely species-specific. We also attempted to characterize putative interspecific hybrids between Q. crispula and Q. dentata sampled in a mixed stand. Two programs, HINDEX and STRUCTURE, were successfully used to detect several hybrid individuals without any prior information about their morphological traits. However, STRUCTURE and HINDEX gave conflicting indications regarding the admixture levels in some individuals.

Unveiling the origin of Quercus serrata subsp. mongolicoides found in Honshu, Japan, by using genetic and morphological analyses

“…; Matsumoto et al . ). Thus, the result at K = 5 was plausible, and the optimal K for the Q. mongolica complex and sympatric congeners was thought to be 5.…”

“…The ΔK, in some cases, underestimates the true value of K (e.g., Bodare et al 2013); in addition, previous studies performed using nuclear DNA markers revealed the genetic distinction of Q. dentata from Q. mongolica var. crispula (Ueno et al 2008;Matsumoto et al 2009). Thus, the result at K = 5 was plausible, and the optimal K for the Q. mongolica complex and sympatric congeners was thought to be 5.…”

“…; Muir & Schlötterer ; Matsumoto et al . ). The use of nuclear microsatellites (simple sequence repeat [SSR]) has been reported to allow species discrimination among oak species because of the high polymorphism, codominance of alleles and highly reproducible polymerase chain reaction (PCR)‐based genotyping methods (Muir et al .…”

“…Therefore, assessments of the geographical variation within and among populations and species delimitation for Quercus species have been conducted using chloroplast DNA (cpDNA) in the last 25 years (Ferris et al 1993;Petit et al 1993;Petit et al 2002;Kanno et al 2004;Okaura et al 2007;Chen et al 2012). However, the use of cpDNA markers is not ideal for discriminating oak species because of the extensive sharing of cpDNA variants among different species; this sharing is thought to result from hybridization and introgression owing to their propensity to inter-cross and/or the preservation of ancestral polymorphism (Petit et al 2003;Muir & Schlötterer 2005;Matsumoto et al 2009). The use of nuclear microsatellites (simple sequence repeat [SSR]) has been reported to allow species discrimination among oak species because of the high polymorphism, codominance of alleles and highly reproducible polymerase chain reaction (PCR)-based genotyping methods (Muir et al 2000;Ueno et al 2008).…”

Environment‐dependent introgression from Quercus dentata to a coastal ecotype of Quercus mongolica var. crispula in northern Japan

“…In northern Japan, there are two species, Quercus dentata Thunberg ( Qd ) in coastal areas and Quercus mongolica Fischer ex Ledebour var. crispula (Blume) H. Ohashi ( Qc ) in inland areas (Matsumoto et al ., ). In northern Hokkaido, the northernmost part of Japan, Qd trees are rare because this region is beyond the northern distributional limit of Qd .…”