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

Abstract

Two alder species (Alnus glutinosa and A. incana) have overlapping distribution, naturally occur in Lithuania, and are considered ecologically and economically important forest tree species. The objective of our study was to estimate the likelihood of spontaneous hybridizations between native alders in natural stands of Lithuania based on leaf morphology and nuclear microsatellite markers. The sampled trees were assigned to the three taxonomic groups of A. glutinosa, A. incana, and potential hybrids based on the leaf and bark morphological traits. The genetic differentiation and potential hybridization between these three groups was tested based on 15 nSSR markers. We identified studied Alnus spp. individuals as pure species and hybrids. Two microsatellite loci were reported as discriminating well between these species. We concluded that our results showed the highest likelihood of two genetic group structures, a clear genetic differentiation between the morphology-based groups of A. glutinosa and A. incana, and rather variable likelihood values in the putative hybrid group. The results provide important implications for genetic conservation and management of Alnus spp.

A Geometric Morphometrics Approach to the Study of Natural Variations and Hybrid Detection in Populations of Alnus incana (L.) Moench and Alnus rohlenae Vít, Douda and Mandák

“…Molecular marker analysis confirmed the predominance of A. incana alleles in A. × pubescens [15,21], indicating that hybrids tend to backcross to A. incana. In the studied populations in Serbia, A. incana was also identified as the mother species, because putative hybrids were found only in A. incana populations.…”

“…Considering various leaf morphological traits, hybrids between black and grey alder overlap with one or both parents or hold an intermediate position and appear to be closer to A. incana [14,16,18]. Multivariate analysis of leaf morphological traits has shown that hybrids have an intermediate position and are closer to A. incana [14,15,19,20]. It was reported by [39] that the germination of a hybrid seed was only successful when A. incana For A. rohlenae, a weak positive correlation between NV and CS was determined in the population PK (R 2 = 0.113, p < 0.05).…”

“…An increased frequency of hybridization is observed at the northern boundary of their range, as well as in years with prolonged winters and cold early springs, when the flowering periods of the two species overlap [14]. This frequency reaches 17.5% in autochthonous populations in Lithuania [15]. On the southern border of the hybrid complex range, [16] reported about 10% of hybrid individuals in the sympatric populations of A. glutinosa and A. incana.…”

“…Various markers have been employed to distinguish and describe hybrids between black and grey alder, including morphological [14,16,[18][19][20], molecular [15,21] and chemical markers [22,23]. For detection in hybrid zones, [24] suggested a combined morphological and genetic approach.…”

Can a Forest Tree Species Progeny Trial Serve as an Ex Situ Collection? A Case Study on Alnus glutinosa

“…In the Vyt ėnai progeny plantation, progenies from 5 out of 10 investigated GCUs were planted: JUO (OP families 135 and 139), MIK (OP family 97), PAZ (OP family 89), BAT (OP family 121), and VIL (OP family 103) (Figure 5). While sampling, care was taken to select only morphologically pure A. glutinosa trees, since in Lithuania, A. glutinosa and Alnus incana have an overlapping distribution [1,43] and the species are known to hybridize occasionally [44][45][46]. Identification of A. glutinosa samples followed the morphological description provided in Flora of Lithuanian TSR [47].…”