An admixture of Quercus dentata in the coastal ecotype of Q. mongolica var. crispula in northern Hokkaido and genetic and environmental effects on their traits

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

“…The coastal Qc ecotype is recognized as a Qc population in the coastal environment in northern Hokkaido, which is genetically admixed with Qd and is phenotypically similar to Qd (Ohba, ; Aizawa et al ., ; Nagamitsu et al ., ). This study confirms these properties quantitatively based on genome‐wide genotypes, multitrait phenotypes, and coastal stress.…”

“…d). The northern limits of the distributional range of Qd are located at 44.8°N on the western side and at 44.5°N on the eastern side of Hokkaido (Nagamitsu et al ., ). We sampled coastal Qd trees from 44.0°N to the northern limits on both sides of Hokkaido and coastal Qc trees from the northern limits to the northernmost part of Hokkaido (Fig.…”

“…To investigate phenotypes of collected samples, we selected 11 morphological traits of leaves and shoots (Table ), which are thought to be distinctive between the two species and to be associated with the tolerance to coastal stress (Nagamitsu et al ., ). We measured the morphological traits of sampled trees as described in Supporting Information Notes S1 and Fig.…”

“…As already mentioned, the bud mortality pattern in shoots reflects coastal stress (Nagamitsu et al ., ). To evaluate coastal stress, we calculated the proportion of flushing buds in the lower part of shoots, n /( m + n ), where m and n are the numbers of flushing buds in the upper and lower parts of a shoot, respectively (Fig.…”

“…Some taxonomists regard the coastal Qc ecotype as a putative hybrid between Qc and Qd (Ohba, ). Nuclear microsatellites demonstrate that an admixture with Qd characterizes the genetic background of the coastal Qc ecotype (Nagamitsu et al ., ). Thus, environment‐dependent introgression from Qd to the coastal Qc ecotype is expected but has not yet been confirmed because incomplete lineage sorting of ancestral polymorphism also produces a similar admixture pattern (Muir & Schlötterer, ; Lexer et al ., ; Pease & Hahn, ).…”