Robert Rutkowski

Differences in genetic variability between two ecotypes of the endangered myrmecophilous butterfly Phengaris (=Maculinea) alcon– the setting of conservation priorities

Abstract.  1. The endangered butterfly Phengaris alcon exists in two ecotypes (P. ‘alcon’ and P. ‘rebeli’), which inhabit contrasting biotopes (wet and warm/dry grasslands respectively) and use different larval food plants. The initially flower‐bud‐feeding caterpillars complete their development as social parasites of Myrmica ants, and the specificity of these relationships shows geographical variation.

Genetic variability of Polish population of the Capercaillie Tetrao urogallus

Abstract. The Capercaillie is one of the most seriously endangered bird species in Poland. It currently numbers around 650 individuals that live in four isolated populations (Lower Silesian Forest, Janów Lubelski Forest, Carpathians, Augustów Forest). This study investigated genetic variability based on the polymorphism of six microsatellite loci in the surviving Polish populations of the Capercaillie and compares the results with the analogous variability in two large, contiguous populations in Russia. The following parameters were estimated: mean number of alleles per locus, allelic richness, mean effective number of alleles per locus, heterozygosity in each of the populations investigated. Differentiation between pairs of populations was assessed using FST. The results show that despite some inevitable reduction in genetic variability, most of the Polish populations retained a substantial level of microsatellite polymorphism. Only in the population from Janów Lubelski Forest was there a significant reduction in variability, probably due to long isolation and the recent decline. That this population has long been isolated was also confirmed by the pronounced genetic differentiation from the other Polish populations. The Carpathian population of the Capercaillie was found to be genetically structured, and in the Lower Silesian Forest population heterozygosity was low, possibly as a result of the lek mating system and also the dramatic reduction in numbers.

A European concern? genetic structure and expansion of golden jackals (canis aureus) in Europe and the caucasus

In the first continent-wide study of the golden jackal (Canis aureus), we characterised its population genetic structure and attempted to identify the origin of European populations. This provided a unique insight into genetic characteristics of a native carnivore population with rapid large-scale expansion. We analysed 15 microsatellite markers and a 406 base-pair fragment of the mitochondrial control region. Bayesian-based and principal components methods were applied to evaluate whether the geographical grouping of samples corresponded with genetic groups. Our analysis revealed low levels of genetic diversity, reflecting the unique history of the golden jackal among Europe’s native carnivores. The results suggest ongoing gene flow between south-eastern Europe and the Caucasus, with both contributing to the Baltic population, which appeared only recently. The population from the Peloponnese Peninsula in southern Greece forms a common genetic cluster with samples from south-eastern Europe (ΔK approach in STRUCTURE, Principal Components Analysis [PCA]), although the results based on BAPS and the estimated likelihood in STRUCTURE indicate that Peloponnesian jackals may represent a distinct population. Moreover, analyses of population structure also suggest either genetic distinctiveness of the island population from Samos near the coast of Asia Minor (BAPS, most STRUCTURE, PCA), or possibly its connection with the Caucasus population (one analysis in STRUCTURE). We speculate from our results that ancient Mediterranean jackal populations have persisted to the present day, and have merged with jackals colonising from Asia. These data also suggest that new populations of the golden jackal may be founded by long-distance dispersal, and thus should not be treated as an invasive alien species, i.e. an organism that is “non-native to an ecosystem, and which may cause economic or environmental harm or adversely affect human health”. These insights into the genetic structure and ancestry of Baltic jackals have important implications for management and conservation of jackals in Europe. The golden jackal is listed as an Annex V species in the EU Habitats Directive and as such, considering also the results presented here, should be legally protected in all EU member states.

Anthropopressure gradients and the population genetic structure of Apodemus agrarius

We have attempted to describe the genetic structure and variability of the striped field mouse population inhabiting 17 locations in and around Warsaw, Poland, within a gradient of anthropopressure and discuss the possible factors that could potentially form the observed pattern. Ecological characteristics of the striped field mouse prevent decreases in genetic variability within local urban populations. High population density, ability to cross environmental barriers and to use “green corridors” allows this species to maintain gene flow in fragmented urban landscape. However, genetic variability and gene flow were efficiently reduced in the central part of the city. The results indicated that the degree of human pressure, defined based on the level of vegetation cover, is a good indicator of isolation. In the studied striped field mouse population, genetic interactions among particular locations (local populations) are modified in comparison with populations inhabiting natural areas, by replacement of the isolation-by-distance pattern of differentiation with the “isolation-by-infrastructure” pattern. As indicated by Bayesian analysis, the urban population from the right side of the Vistula river form common genetic cluster with ex-urban population located northward from the city, while the population from the left side of the river probably exchanges genes with neighbouring northern and southern ex-urban populations. However local populations at locations within the highest zone of anthropopressure are clearly isolated, and presently constitute separate genetic units.

Contrasting genetic structure of rear edge and continuous range populations of a parasitic butterfly infected by Wolbachia

BackgroundClimatic oscillations are among the long-term factors shaping the molecular features of animals and plants and it is generally supposed that the rear edges (i.e., the low-latitude limits of distribution of any given specialised species) situated closer to glacial refugia are vital long-term stores of genetic diversity. In the present study, we compared the genetic structure of several populations of an endangered and obligate myrmecophilous butterfly (Maculinea arion) from two distinct and geographically distant parts of its European distribution (i.e., Italy and Poland), which fully represent the ecological and morphological variation occurring across the continent.ResultsWe sequenced the COI mitochondrial DNA gene (the ‘barcoding gene’) and the EF-1α nuclear gene and found substantial genetic differentiation among M. arion Italian populations in both markers. Eleven mtDNA haplotypes were present in Italy. In contrast, almost no mtDNA polymorphisms was found in the Polish M. arion populations, where genetic differentiation at the nuclear gene was low to moderate. Interestingly, the within-population diversity levels in the EF-1α gene observed in Italy and in Poland were comparable. The genetic data did not support any subspecies divisions or any ecological specialisations. All of the populations studied were infected with a single strain of Wolbachia and our screening suggested 100% prevalence of the bacterium.ConclusionsDifferences in the genetic structure of M. arion observed in Italy and in Poland may be explained by the rear edge theory. Although we were not able to pinpoint any specific evolutionarily significant units, we suggest that the Italian peninsula should be considered as a region of special conservation concern and one that is important for maintaining the genetic diversity of M. arion in Europe. The observed pattern of mtDNA differentiation among the populations could not be explained by an endosymbiotic infection.

Population genetics and bat rabies: a case study of Eptesicus serotinus in Poland

The serotine bat, Eptesicus serotinus is the most frequently rabies-infected (European bat lyssavirus 1-type, EBLV-1) bat species in Europe. To confirm Lyssavirus infection of this bat in Poland, we tested for the presence of rabies virus RNA from oropharyngeal swabs using RT-PCR. There was a 0.9% (two out of 212 individuals) level of infection within the overall population of serotine bats studied. However, an appreciation of the potential for pathogen transmission and disease risk requires an understanding of the dispersal of the primary host, and any large-scale geographic barriers that may impede gene flow. Thus, we also studied the patterns of bat dispersal via population genetics using nuclear (seven microsatellite loci) and mitochondrial (mtDNA control region) markers, examined in 12 subpopulations distributed across the country. Molecular analyses of microsatellite loci indicated high genetic diversity at all sites (heterozygosity observed, H o = 0.53–0.78), and extremely weak genetic structure in the Polish population of the species. The overall F ST was 0.012 (95% confidence interval: 0.006–0.020), and pairwise values ranged from 0.00 to 0.05. Only 22% of individuals were assigned to the subpopulation from which they were sampled. The Bayesian approach implemented in STRUCTURE also confirmed that all examined subpopulations should be treated as a single group, indicating a high level of gene flow. There was some evidence for female philopatry (genetic differentiation was greater in maternally-inherited mtDNA than nuclear DNA) and male-biased dispersal, e.g., H o and the variance of mean assignment were significantly higher in males than in females. Twelve individuals (seven females and five males) were identified as potential first generation migrants. Their migration routes ranged from 60–283 km in females ( ± SE = 177.9 ± 29.37) to 27–385 km in males (206.4 ± 58.95); surprisingly, no sexual differences were observed and this finding suggests that female-mediated gene flow may occur. MtDNA also produced a strong genetic signal for the demographic expansion (Fus F S statistics, F S = -26.30, P < 0.01 and a star-shaped haplotype network), which took place roughly 33,000 years BP, i.e., before the Last Glacial Maximum. The genetic uniformity of the Polish population implies that there is no migration barrier to EBLV-1, at least within the country, and the potential threat of rabies virus spreading via migration of infected animals may be higher than previously thought.

Population genetics of the hazel hen Bonasa bonasia in Poland assessed with non-invasive samples

Despite a severe decrease in the number of hazel hens during the 20th century, nowadays this grouse species is rather common in the forests of Northeastern and Southern Poland. We used mitochondrial control region and microsatellite markers to examine the genetic variability of Polish populations of hazel hens. We used non-invasively collected faeces to estimate genetic variability within populations, genetic differentiation among populations as well as genetic differentiation between two regions inhabited by two different subspecies of hazel hens. Our results confirm the usefulness of DNA from faeces to obtain reliable information on the population genetics of hazel hens. We found a rather high level of genetic variability in the Polish population. Genetic variability was higher in birds from continuous forests in the South of the country than in birds from fragmented habitats in the Northeast. Genetic differentiation was higher among subpopulations from Northeastern Poland. Additionally, both classes of molecular markers suggested the presence of two distinct genetic groups of birds, corresponding to previously described subspecies. We conclude that the genetic variability of the Polish hazel hen population has been influenced by habitat fragmentation and the history of the population during its post-glacial colonization of Poland from different glacial refugia.

Landscape pattern and genetic structure of a yellow-necked mouse Apodemus flavicollis population in north-eastern Poland

Reduced connectivity among local populations inhabiting a spatially heterogeneous landscape may restrict gene flow and thus contribute to diminished genetic variation within a population. The aim of this study was to determine the role of geographic distance and habitat barriers in developing genetic structure of a yellow-necked mouse Apodemus flavicollis (Melchior, 1834) population, taking into consideration the spatial organization of the landscape. A field study was carried out in two plots located in NE Poland that differed considerably in terms of the scale of habitat fragmentation: (1) a continuous forest complex, and (2) a mosaic of smaller forest habitats. The plots were separated by a water barrier comprised of a chain of lakes. DNA samples from a total of 654 individuals were examined by microsatellite analysis (5 loci). The results showed that the yellow-necked mouse population was characterized by a poorly pronounced genetic structure throughout the study area, although the statistical significance of FST for most location pairs indicated that gene flow in the area was not free. The division of the mouse population into three genetically distinct groups clearly demonstrated the significant role of water bodies as a natural barrier effectively hindering free movement of animals and thus gene flow. Analysis of the genetic structure of the mouse population throughout the study area and also within the distinguished groups indicated that the entire study population may be considered as a single metapopulation. Our results suggest that geographic distance alone is not the predominant factor affecting the genetic structure of population, but in the mosaic landscape the relative isolation of individual forest fragments, and barriers hindering movements of individuals and limiting gene flow among local populations played a much more important role.

Multiple paternity in a wild population of the yellow-necked mouseApodemus flavicollis

Multiple paternity has been described in a wide range of taxonomic groups (eg invertebrates, fish, reptiles, birds, mammals). In rodents, multiple paternity seems to be common and can lead to both genetic (eg increase in offspring diversity, avoiding inbreeding) and direct (eg higher survival rate of the litter) benefits. The primary aim of this study was to confirm multiple paternity and evaluate its frequency in a wild population of yellow-necked mouseApodemus flavicollis (Melchior, 1834). Animals were trapped in north-eastern Poland in 2004–2006. Five microsatellite loci previously described for members of the genusApodemus were used to examine the occurrence of multiple paternity among the offspring of 10 pregnant females. The analyses were performed using multiplex PCR, estimating the length of amplified fragments with an automated sequencer. The presence of additional alleles indicating multiple paternity was found in 30% (3 out of 10) of the investigated litters. Offspring fathered by a single male were predominant in each litter, with the proportion of individuals originating from other males varying from 16.7 to 20% in the three multiple paternity cases. Our findings indicate that the promiscuous mating system may be considered as an alternative breeding strategy in the yellow-necked mouse.

Local Heterozygosity Effects on Nestling Growth and Condition in the Great Cormorant

Under inbreeding, heterozygosity at neutral genetic markers is likely to reflect genome-wide heterozygosity and, thus, is expected to correlate with fitness. There is, however, growing evidence that some of heterozygosity-fitness correlations (HFCs) can be explained by ‘local effects’, where noncoding loci are at linkage disequilibrium with functional genes. The aim of this study was to investigate correlations between heterozygosity at seven microsatellite loci and two fitness-related traits, nestling growth rate and nutritional condition, in a recently bottlenecked population of great cormorant Phalacrocorax carbo sinensis. We found that heterozygosity was positively associated with both nestling traits at the between-brood level, but the individual (within-brood) effects of heterozygosity were non-significant. We also found that only one locus per trait was primarily responsible for the significant multi-locus HFCs, suggesting a linkage disequilibrium with non-identified functional loci. The results give support for ‘local effect’ hypothesis, confirming that HFCs may not only be interpreted as evidence of inbreeding and that genetic associations between functional and selectively neutral markers could be much more common in natural populations than previously thought.