Reproduction and diversity of the endangered Salix lapponum L. populations in Eastern Poland

Abstract

The main aim of the study was to increase the knowledge on the ecology and biology of the boreal relict Salix lapponum L., an endangered plant in Poland, in order to create an effective protection program. An important aspect was to determine the within-and among-population genetic diversity of the studied species in order to evaluate whether the basic stages of the generative reproduction cycle in the populations were correct. The results confirmed that S. lapponum pollen viability and germinability, for both fresh and stored pollen, were high and so were the seed germination ability and dynamics. All individuals were of sexual origin and the expected heterozygosity was moderate. In spite of this, young individuals were observed in only 1 out of 5 studied populations and it was the most numerous one. Although the genetic diversity among the populations was not very high (Φ PT = 0.12), it accumulated in a quite short period of time, probably during the second part of the 20th century, as a consequence of habitat fragmentation. A lack of gene flow, either by pollen or seeds, may lead to further differentiation of the populations and extinction of the smallest ones. For this reason, preventive measures should be undertaken in order to enlarge the existing populations and to reconstruct S. lapponum populations in selected sites where environmental conditions are the most similar to those preferred by this species.

Genetic diversity of the Salix lapponum L. population intended as a source of material for reintroduction

“…It was similar in the case of the G ST coefficient. These values were especially surprising in the light of the results described in the paper by Pogorzelec et al (2014c), where the genetic diversity obtained by ISSR markers between four populations located in the Łęczna-Włodawa Lakeland was twice smaller. The present Φ PT value may result from very high linkage disequilibrium of loci, which was especially high at the whole population level, and from applying the AFLP method whose results in many publications significantly differ from those obtained by ISSR (Abdelhamid et al, 2014;Badfar-Chaleshtori et al, 2012;Chen et al, 2010;Khadivi-Khub & Soorni, 2014).…”

“…The present population is only a small fraction of the one that existed over a dozen years ago and therefore it should be assumed that the alleles, also including rare or even unique ones, have been lost together with the lost individuals. From another point of view, the Bikcze population is still the most numerous in eastern Poland and the only one with 100% polymorphic loci (Pogorzelec et al, 2014c). It is not certain what factor caused such sudden extinction of so many individuals, but it can surely be said that the population has been genetically impoverished to a large extent.…”

“…Unfortunately, each successive generation produced by generative reproduction in a population whose habitat has been fragmented is usually characterized by a much lower level of heterozygosity (Aguilar et al, 2008;Gareca et al, 2013). Taking into account that it is the only population in Łęczna-Włodawa Lakeland with young individuals, this can be a reason for the smallest value of heterozygosity of the Bikcze population in Pogorzelec et al (2014c). Due to that fact, the studied population should be used as quickly as possible as a donor of reproductive material in the form of both seeds and organ parts for in vitro regeneration.…”

“…This is a group of plants that is characterized by a stable sex ratio (1 : 1). Each year, more than 70% of individuals flower and produce seeds capable of germination (Pogorzelec et al, 2014c). However, since 2000 this population has tended to quickly reduce its resources, simultaneously exhibiting low recruitment of seedlings or the complete absence of seedling recruitment (Pogorzelec et al, 2014a).…”

“…Multidirectional research on S. lapponum has been conducted in the Polesie Lubelskie region since 2000 and it includes issues related both to the functioning of its populations (among others, changes in population numbers, sex ratio, among-and within-population genetic diversity) and to particular individuals (selected key stages of the breeding cycle) (Pogorzelec et al, 2014c). Active conservation of this species, involving the establishment of new populations and the replenishment of the existing populations occurring in the Polesie National Park, should be an action that will be the ultimate outcome of the efforts to fully get to know this species.…”