Hybridization of Populus nigra L. and P. laurifolia Ledeb. (Salicaceae) in the floodplain of the Tom river

Abstract

Natural hybrid zones are of the considerable interest to genetic-evolutionary researches. Natural hybridization is recognized as the mechanism of transfer of genes between types for a long time and has important evolutionary consequences. Trans-species hybridization is characteristic of the sort Populus L., though, as a rule, it is restricted to representatives of one section. The exception is made by types of the section Aigeiros and Tacamahaca, which are rather freely crossed, but at the same time save the integrity and are well differentiated. As show numerous researches, prezygotic mechanisms of reproductive insulation aren’t capable to restrict hybridization between types of these sections, but perhaps define its asymmetry. In hybrid zones in case of transposition of types of different sections among hybrid descendants F1 prevail. Hybrids of the subsequent generations and a bekkrossa are discarded by selection before a reproductive maturity. Carried out based on the complex analysis of morphological features of leaves and escapes of P. nigra (Aigeiros), P. laurifolia (Tacamahaca) and their natural hybrids in a flood plain of the Tom River (The Kemerovo region of the Russian Federation) of a research also showed that observed hybridization has one-sided, asymmetrical character, hybrids turn aside lavrolistny poplar. Despite duration of the proceeding hybridization in a flood plain of the Tom River P. nigra and P. laurifolia well differ. Natural hybrids meet preferentially on flood plain sections where P. laurifolia grows in an equal share with P. nigra. Perhaps, the frequency of occurrence of hybrids depends also on sexual structure of local populations of pure types. The exception is made by sections with the considerable anthropogenous impact, which can be considered as «hybrid habitats».

Keywords

• Poplar
• identification
• asymmetric hybridization
• hybrid zones
• genotype