Sympatric genome size variation and hybridization of four oak species as determined by flow cytometry genome size variation and hybridization

Abstract

The Quercus species serve as a powerful model for studying introgression in relation to species boundaries and adaptive processes. Coexistence of distant relatives, or lack of coexistence of closely relative oak species, introgression may play a role. In the current study, four closely related oak species were found in Zijinshan, China. We generated a comprehensive genome size (GS) database for 120 individuals of four species using flow cytometry‐based approaches. We examined GS variability within and among the species and hybridization events among the four species. The mean GSs of Q. acutissima, Q. variabilis, Q. fabri, and Q. serrata var. brevipetiolata were estimated to be 1.87, 1.92, 1.97, and 1.97 pg, respectively. The intraspecific and interspecific variations of GS observed among the four oak species indicated adaptation to the environment. Hybridization occurred both within and between the sections. A hybrid offspring was produced from Q. fabri and Q. variabilis, which belonged to different sections. The GS evolutionary pattern for hybrid species was expansion. Hybridization between the sections may be affected by habitat disturbance. This study increases our understanding of the evolution of GS in Quercus and will help establish guidelines for the ecological protection of oak trees.

Karyotype and LTR-RTs analysis provide insights into oak genomic evolution

“…Identical and species-speci c chromosomal rearrangements within oaks were shown in the ancestor karyotype projection and interspeci c synteny relationships. In oaks, research has revealed the importance of natural hybridization and introgression in promoting genetic diversity and the generation of new species [52,53]. Identical chromosomal rearrangements among oaks are associated with the evolution of Quercus' common ancestor, and these rearrangements may have been preserved in frequent hybridization and have the effect of inhibiting recombination [54,55].…”

Karyotype and LTR-RTs analysis provide insights into oak genomic evolution

“…Identical and species-specific chromosomal rearrangements within oaks were shown in the ancestor karyotype projection and interspecific synteny relationships. In oaks, research has revealed the importance of natural hybridization and introgression in promoting genetic diversity and the generation of new species [ 53 , 54 ]. Identical chromosomal rearrangements among oaks are associated with the evolution of Quercus ’ common ancestor, and these rearrangements may have been preserved in frequent hybridization and have the effect of inhibiting recombination [ 55 , 56 ].…”

Spatial Distribution and Ecological Determinants of Coexisting Hybrid Oak Species: A Study in Yushan’s Mixed Forest

“…Nakai. Our preliminary molecular work has confirmed introgressive hybridization among these species [29,30]. In this study, we delve into the intra-and interspecific spatial relationships of these oaks using Point Pattern Analysis (PPA).…”

“…brevipetiolata-are prominently established within these woodlands, exhibiting partial sympatric distribution points. Analysis of genetic diversity and variation in Quercus populations, both at large and local scales, showed that there are many introgressions among these four oak species [29,30]. Thus, from an evolutionary perspective, studying the spatial distribution characteristics of hybrid mixed forests composed of multiple oak species not only helps in revealing the interaction between species and environment but also helps in understanding species distribution patterns and coexistence.…”