Additivity of ISSR Markers in Natural Hybrids of Related Forest Species Bromus benekenii and B. ramosus (Poaceae)

Abstract

The co-occurrence of hybrids and parental species in similar ecological niches poses a question on the role of traits additivity and overdispersion (emergence of new traits) in microevolutionary processes. We analysed genetic polymorphism of Bromus benekenii, B. ramosus and the spontaneous hybrid B. benekenii × B. ramosus in sympatric and allopatric parts of the species distribution in Europe, based on non-coding regions of the taxon genomes (ISSR genetic fingerprinting). We tested 68 individuals in 7 populations, including a hybrid population in N France. Altogether 233 polymorphic ISSR bands (loci) were obtained. We found that the parent species were genetically distinct and the hybrids had an additive pattern of ISSR bands found in the putative parental species (NMDS, STRUCTURE); however, there was evidence of introgression towards B. ramosus (NEWHYBRIDS, UPGMA classifications, Nei's D genetic distance). Bromus benekenii had 72, B. ramosus 21 and the hybrids 9 private bands (genetic overdispersion), probably resulting from the rearranged genomes. Based on its low genetic divergence index DW, the hybrid population seems to be at a young age. We argue that in the face of anthropogenic landscape transformations favouring secondary contacts, the hybrids may competitively replace the parental species in sympatric areas. K Ke ey y w wo or rd ds s: : Genetic additivity, hybrid zone, introgression, ISSR, Linnaean taxonomy, microevolution.

Genetic Characterization of an Endangered Chilean Endemic Species, Prosopis burkartii Muñoz, Reveals its Hybrids Parentage

“…The ISSR markers showed a high number of polymorphic bands when looking at the (21) individuals from the Strombocarpa section ( P. tamarugo , P. burkartii , P. strombulifera and P. reptans ), and specific primers (UBC810, UBC825, UBC815 and UBC850) showed a high content of polymorphic information. Of the various genetic tools used to study hybridization in plants, the ISSR marker is one of the simplest molecular methods that can be used for comparative analysis of possible hybrids and parental species [ 10 , 30 , 31 , 32 ]. The electrophoresis patterns of seven ISSR primers showed up to 19 bands shared between P. burkartii and the species P. tamarugo , P. strombulifera and P. reptans .…”

Hybridization and introgression among three Aconitum (Ranunculaceae) species of different ploidy levels in the Tatra Mountains (Western Carpathians)

“…Also, if a population persists for a long time, there may be an increase in its variability via recombinations and random mutations (Sutkowska et al . ).…”

Limited gene flow in adjacent valleys and genetic introgression in a mountain hybrid zone between <i>Aconitum</i> (Ranunculaceae) species

“…×pawlowskii, it had no additive (parental) ISSR loci. An additive contribution of the genomes of two parental species has been uncovered, for example, in natural hybrids between the forest grass species Bromus benekenii and B. ramosus (Sutkowska et al, 2015) and likewise, Phoenix canariensis and P. dactylifera (Gonzalez-Perez et al, 2004). Similar results were obtained while studying two fir species in the narrow contact zone at an elevation of 1,000-1,100 m in Japan, where nine of 78 tree individuals were genetically intermediate and natural hybrids, whose genetic analysis confirmed they had backcrossed with parental species; it turns out that the hybrid species of intermediate morphology had previously taxonomic independent status (Aizawa & Iwaizumi, 2020).…”