Hybridization and introgression in sympatric and allopatric populations of four oak species

Abstract

Background Hybridization and introgression are vital sources of novel genetic variation driving diversification during reticulated evolution. Quercus is an important model clade, having extraordinary diverse and abundant members in the Northern hemisphere, that are used to studying the introgression of species boundaries and adaptive processes. China is the second-largest distribution center of Quercus, but there are limited studies on introgressive hybridization. Results Here, we screened 17 co-dominant nuclear microsatellite markers to investigate the hybridization and introgression of four oaks (Quercus acutissima, Quercus variabilis, Quercus fabri, and Quercus serrata) in 10 populations. We identified 361 alleles in the four-oak species across 17 loci, and all loci were characterized by high genetic variability (HE = 0.844–0.944) and moderate differentiation (FST = 0.037–0.156) levels. A population differentiation analysis revealed the following: allopatric homologous (FST = 0.064) < sympatric heterogeneous (FST = 0.071) < allopatric heterogeneous (FST = 0.084). A Bayesian admixture analysis determined four types of hybrids (Q. acutissima × Q. variabilis, Q. fabri × Q. serrata, Q. acutissima × Q. fabri, and Q. acutissima × Q. variabilis × Q. fabri) and their asymmetric introgression. Our results revealed that interspecific hybridization is commonly observed within the section Quercus, with members having tendency to hybridize. Conclusions Our study determined the basic hybridization and introgression states among the studied four oak species and extended our understanding of the evolutionary role of hybridization. The results provide useful theoretical data for formulating conservation strategies.

Identification of Alnus glutinosa L. and A. incana (L.) Moench. Hybrids in Natural Forests Using Nuclear DNA Microsatellite and Morphometric Markers

“…Meanwhile, A. glutinosa is most common on wet sites in the lowlands of central Lithuania and in the southwestern part of the country. However, warming climates often alter the site moisture regime, thus providing better chances for co-occurrence and hybridization among tree species that may lead to sympatric speciation events following the global environmental change [101]. Our study provides strong evidence for such sympatric speciation events among alder species complex in overlapping natural habitats.…”

Genetic structure and geneflow of Malus across the Korean Peninsula using genotyping-by-sequencing

“…2 ) and should be treated as a separate lineages generated by hybridization between C5 (JJ2 and JJ3) and M. baccata (Fig. 5 ) 95 , 96 . Additionally, one-sided genetic invasion from C5 to M. baccata is presumed to be the result of asymmetric hybridization, where C5 acts as a pollen donor and M. baccata as a pollen acceptor (Fig.…”

Local environmental adaptation contributes to the maintenance of ecotypes of Callicarpa subpubescens (Lamiaceae), in spite of frequent hybridization and low pre- and post-mating barriers

“…largest Q < 0.6 was defined as first or second filial generation hybrids (F 1 or F 2 ), and hybrids with 0.6 [?] largest Q < 0.9 as backcross hybrids (Li et al, 2021).…”

“…In this analysis, we defined that the genetic cluster with the largestQ value as the ecotype of the adult trees, and trees assignedQ [?] 0.9 for each cluster as pure adult trees, and Q< 0.9 as hybrid adult trees (Kato et al, 2014;Li et al, 2021). The hybridization rate for each ecotype was calculated as the percentage of hybridized trees relative to the total number of trees exhibiting the ecotype.…”