Abstract
Hybridization is an important evolutionary force, because interspecific gene transfer can introduce more new genetic material than is directly generated by mutations. Pinus engelmannii Carr. is one of the nine most common pine species in the pine-oak forest ecoregion in the state of Durango, Mexico. This species is widely harvested for lumber and is also used in reforestation programmes. Interspecific hybrids between P.engelmannii and Pinus arizonica Engelm. have been detected by morphological analysis. The presence of hybrids in P. engelmannii seed stands may affect seed quality and reforestation success. Therefore, the goals of this research were to identify introgressive hybridization between P. engelmannii and other pine species in eight seed stands of this species in Durango, Mexico, and to examine how hybrid proportion is related to mean genetic dissimilarity between trees in these stands, using Amplified Fragment Length Polymorphism (AFLP) markers and morphological traits. Differences in the average current annual increment of putative hybrids and pure trees were also tested for statistical significance. Morphological and genetic analyses of 280 adult trees were carried out. Putative hybrids were found in all the seed stands studied. The hybrids did not differ from the pure trees in vigour or robustness. All stands with putative P. engelmannii hybrids detected by both AFLPs and morphological traits showed the highest average values of the Tanimoto distance, which indicates: i) more heterogeneous genetic material, ii) higher genetic variation and therefore iii) the higher evolutionary potential of these stands, and iv) that the morphological differentiation (hybrid/not hybrid) is strongly associated with the Tanimoto distance per stand. We conclude that natural pairwise hybrids are very common in the studied stands. Both morphological and molecular approaches are necessary to confirm the genetic identity of forest reproductive material.
Highlights
Hybridization and backcrossing to one or both of the parental types can lead to incorporation of alleles from one taxon into the gene pool of the other [1]
The Amplified Fragment Length Polymorphism (AFLP) primer combination resulted in 204 polymorphic bands of 75–450 base pairs across all individuals of Pinus engelmannii (Pe), P. arizonica var. cooperi (Pco) and P. durangensis (Pdu)
Pe shared 87% of AFLP fragments with Pinus arizonica var. cooperi (Pco) and 90% with Pinus durangensis (Pdu)
Summary
Hybridization and backcrossing to one or both of the parental types can lead to incorporation of alleles from one taxon into the gene pool of the other [1]. Interactions between environment and genetic structure can lead to segregation of a novel taxon from parental types. Hybridization is an important evolutionary force, because interspecific gene transfer can introduce more new genetic material than is directly generated by mutation [4]. At least 30%, and possibly as much as 80%, of all species may have been originated by hybridization [5]. As narrow geographic regions and “tension zones”, hybrid zones are active sites of evolutionary change and high levels of genetic variation [1] [3]. A hybrid species probably originates from a hybrid founder event, in which one or more early generation hybrids populate a new area and become spatially or ecologically isolated from the parent species [7] [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
