Abstract
The Viola epipsila-V. palustris complex is a highly taxonomically complicated group of species in its entire circumboreal range of distribution. Habitat loss, forest flooding, and hybridization could lead to the extinction of V. epipsila. A hybrid index and principal component analysis (PCA) were used to select qualitative and quantitative morphological features to distinguish parent species and hybrids, inter simple sequence repeat (ISSR) markers to determine the genetic diversity of the populations, flow cytometry to estimate the genome size (GS), and non-coding chloroplast DNA (cpDNA) regions to indicate the directions of crosses. All taxa are very morphologically variable, and their features can change within a season. The most stable feature is the distance of the bracts on the pedicel from the rhizome. The genetic diversity of all taxa populations is low and highly influenced by selfing and vegetative propagation. The population structure is differentiated: populations of V. epipsila or V. palustris, mixed populations with both parent species, F1 hybrids and populations with introgressive forms occur in different regions. The interspecific GS variation corresponds to the ploidy level (4x = 2.52 pg, 8x = 4.26 pg, 6x = 3.42 pg). Viola epipsila is the mother plant of the hybrids. Research has shown the risk of V. epipsila extinction in Central Europe and the importance of local populations in studying the role of hybridization in reducing/maintaining/increasing biodiversity.
Highlights
Genetic diversity of species is constantly changing under the influence of various factors.The consequences of global climate changes are: the future species distribution, the borders of species range and fate of a species or ecological communities, and biodiversity [1]
Viola epipsila and V. palustris occur on marches, wetlands, and could be considered as indicators of peatlands
The range of both species, especially V. epipsila, in Central Europe drastically decreased which indicates that the habitats of these species, i.e., peatlands, are disappearing due to climate change
Summary
Genetic diversity of species is constantly changing under the influence of various factors.The consequences of global climate changes are: the future species distribution, the borders of species range and fate of a species or ecological communities, and biodiversity [1]. Genetic diversity of species is constantly changing under the influence of various factors. The persistence of existing levels of genetic diversity in plant populations under climate change determines species life history, availability of habitats or migration routes, breeding system, and current range sizes. The genetic diversity is influenced by hybridization, leading to loss of biodiversity (in disturbed habitats species might be displaced by interspecific hybrids) or to biodiversity enhancement (origin of new ecotypes and species). Contemporary (recent) hybridization might lead to genetic diversity of populations by introducing new hybrid genotypes resulting from the introgression of novel alleles; transgressive segregation; and to local adaptation [4,5,6,7,8]. DNA sequence data and other sophisticated molecular methods allow us to distinguish types of hybrids, estimate the frequency of hybridization, and detect recent and ancient hybridization [10,11]
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