RESUMO
Progressive changes in the environment are related to modifications of the habitat. Introducing exotic species, and interbreeding between species can lead to processes that in the case of rare species or small populations threatens their integrity. Given the declining trends of many populations due to increased hybridization, early recognition of hybrids becomes important in conservation management. Natural hybridization is prevalent in Jacobaea. There are many naturally occurring interspecific hybrids in this genus, including those between Jacobaea vulgaris and its relatives. Although Jacobaea erucifolia and J. vulgaris often co-occur and are considered closely related, apart from the few reports of German botanists on the existence of such hybrids, there is no information on research confirming hybridization between them. Morphologically intermediate individuals, found in the sympatric distributions of J. vulgaris and J. erucifolia, were hypothesized to be their hybrids. Two molecular marker systems (nuclear and chloroplast DNA markers) were employed to test this hypothesis and characterize putative hybrids. Nuclear and chloroplast DNA sequencing results and taxon-specific amplified fragment length polymorphism (AFLP) fragment distribution analysis confirmed the hybrid nature of all 25 putative hybrids. The AFLP patterns of most hybrids demonstrated a closer relationship to J. erucifolia, suggesting frequent backcrossing. Moreover, they showed that several individuals previously described as pure were probably also of hybrid origin, backcrosses to J. erucifolia and J. vulgaris. This study provides the first molecular confirmation that natural hybrids between J. vulgaris and J. erucifolia occur in Poland. Hybridization appeared to be bidirectional but asymmetrical with J. vulgaris as the usual maternal parent.
RESUMO
The generally-accepted paradigm of wetland response to climate change is that water table drawdown and higher temperatures will cause wetlands to switch from a sink to a source of atmospheric carbon. However, it is hard to find a multi-year, ecosystem scale dataset representative of an undisturbed wetland that clearly demonstrates this paradigm on an annual total basis. Here we provide strong empirical confirmation of the above scenario based on six years of continuous eddy-covariance CO2 and CH4 flux measurements in Biebrza Valley, north-eastern Poland. In wet years the mire was a significant sink of atmospheric carbon (down to -270 ± 70 gC-CO2 m-2 yr-1 against +21.8 ± 3.4 gC-CH4 m-2 yr-1 in 2013) whereas in dry years it constituted a substantial carbon source (releasing up to +130 ± 70 gC-CO2 m-2 yr-1 and +2.6 ± 1.4 gC-CH4 m-2 yr-1 in 2015). Our findings demonstrate that the scenario of positive feedback between wetland carbon release and the present climate change trajectory is realistic and support the need of natural wetland preservation or rewetting. Our findings also indicate that conclusions drawn regarding a wetland's response to changing climate can depend strongly on the chosen period of analysis.
RESUMO
Dormant buds collected from 35 wild service trees (Sorbus torminalis) in the Bytyn Forest were tested with horizontal gel electrophoresis to assess the genetic structure of the population. Among 16 investigated isozyme loci, seven loci (ADH-A, 6PGD-A, GDH-B, ME-A, SOD-A, PGM-A, PGM-B) proved to be polymorphic, whereas the other nine loci (SDH-A, SDH-B, DIA-C, DIA-D, FLE-A, FLE-B, GOT-B, IDH-A, IDH-B) were monomorphic. The number of alleles per polymorphic locus ranged from two to three, with a mean of 2.29. The average observed and expected heterozygosities were 0.2665 and 0.3462, respectively. The combined FIS value over all polymorphic loci was 0.2179, which reflects a substantial deficit of heterozygotes. Two polymorphic loci (SOD-A, PGM-A) were identified in S. torminalis for the first time.
