Purging of deleterious burden in the endangered Iberian lynx

Deleterious mutations continuously accumulate in populations, building up a burden that can threaten their survival, particularly in small populations when inbreeding exposes recessive deleterious effects. Notwithstanding, this process also triggers genetic purging, which can reduce the deleterious burden and mitigate fitness inbreeding depression. Here, we analyzed 20 whole genomes from the endangered Iberian lynx and 28 from the widespread Eurasian lynx, sister species which constitute a good model to study the dynamics of deleterious mutation burden under contrasting demographies, manifested in the consistently smaller population size and distribution area of the Iberian lynx. We also derived analytical predictions for the evolution of the deleterious burden following a bottleneck. We found 11% fewer derived alleles for the more putatively deleterious missense category in the Iberian lynx than in the Eurasian lynx, which, in light of our theoretical predictions, should be ascribed to historical purging. No signs of purging were found in centromeres nor in the X chromosome, where selection against recessive deleterious alleles is less affected by demography. The similar deleterious burden levels for conspecific populations despite their contrasting recent demographies also point to sustained differences in historical population sizes since species divergence as the main driver of the augmented purging in the Iberian lynx. Beyond adding to the ongoing debate on the relationship between deleterious burden and population size, and on the impact of genetic factors in endangered species viability, this work contributes a whole-genome catalog of deleterious variants, which may become a valuable resource for future conservation efforts

Coat Polymorphism in Eurasian Lynx: Adaptation to Environment or Phylogeographic Legacy?

We studied the relationship between the variability and contemporary distribution of pelage phenotypes in one of most widely distributed felid species and an array of environmental and demographic conditions. We collected 672 photographic georeferenced records of the Eurasian lynx throughout Eurasia. We assigned each lynx coat to one of five phenotypes. Then we fitted the coat patterns to different environmental and anthropogenic variables, as well as the effective geographic distances from inferred glacial refugia. A majority of lynx were either of the large spotted (41.5%) or unspotted (uniform, 36.2%) phenotype. The remaining patterns (rosettes, small spots and pseudo-rosettes) were represented in 11.0%, 7.4%, and 3.9% of samples, respectively. Although various environmental variables greatly affected lynx distribution and habitat suitability, it was the effect of least-cost distances from locations of the inferred refugia during the Last Glacial Maximum that explained the distribution of lynx coat patterns the best. Whereas the occurrence of lynx phenotypes with large spots was explained by the proximity to refugia located in the Caucasus/Middle East, the uniform phenotype was associated with refugia in the Far East and Central Asia. Despite the widely accepted hypothesis of adaptive functionality of coat patterns in mammals and exceptionally high phenotypic polymorphism in Eurasian lynx, we did not find well-defined signs of habitat matching in the coat pattern of this species. Instead, we showed how the global patterns of morphological variability in this large mammal and its environmental adaptations may have been shaped by past climatic change.publishedVersio

From population genetics to population genomics: new perspectives in ecology and evolutionary biology

Application of molecular methods in biology has revolutionized ecology, population genetics and evolutionary biology. For example, the molecular studies revealed complex mating systems and social structures. Analysis of molecular markers revealed the existence of cryptic boundaries such as secondary contact (hybrid zones) among previously isolated populations. Most recently, due to simultaneous study of numerous loci (the population genomics approach), the distribution of estimates of genetic differentiation (Fst) from individual loci has allowed the identification of candidate loci to be under selection. Such analyses may help answer many important evolutionary questions and will also improve inferences in classical population genetics dealing with demography and evolutionary history. Several papers concerning interesting aspects of population genetics and molecular ecology revealed by Polish scientists are discussed and future perspective for population genomics approach are highlighted

Historical events, genetic and environmental barriers - their impact on gene flow and population structure in animals

In many species genetic distances increase with geographic distances, resulting in the “isolation by distance” (IBD) pattern. However, more complex patterns usually are observed in heterogeneous habitats. Geographic obstacles limit gene flow in a discontinuous way and might confound a simple IBD relationship. Moreover, current population structure is not only determined by present-day evolutionary processes but also shaped by population history. Barriers to gene flow lead to differences in gene pool composition among populations, so that molecular population genetics methods should allow these barriers to be detected. It is also possible to identify cryptic boundaries, which may represent secondary contacts among previously isolated populations. Landscape genetics approach that combines molecular population genetics and landscape ecology aims to detect such genetic discontinuities and to correlate them with environmental features. In this paper, the effects of genetic and environmental factors that affect population genetic structure and population history, are explored with a focus on the following examples: (1) the common vole populations in heterogeneous habitats of the Biebrza valley in NE Poland; (2) red deer populations in France that experienced isolation and translocations; (3) different chromosome races of the common shrew in Poland forming hybrid zones and (4) two sympatric subspecies of the chequered skipper in the Białowieża Primeval Forest, NE Poland. Implications of such approaches for evolutionary biology, ecology and conservation biology are discussed in the context of most recent achievements in the field

Simultaneous Infection of Elaphostrongylus Nematode Species and Parasite Sharing between Sympatrically Occurring Cervids: Moose, Roe Deer, and Red Deer in Poland

It is important to assess the distribution of parasite species across wildlife populations, to design strategies for game management and effective disease control in nature. In this project we quantified the prevalence of Elaphostrongylus species in eight moose populations. We used molecular methods for identification of parasite species and host individual genotypes from fecal samples. We also demonstrated sharing of parasite species between three cervid hosts sympatrically occurring in the Biebrza River valley, North-Eastern Poland, which is occupied by the largest autochthonous, non-harvested moose population in Central Europe. Nematode species from the genus Elaphostrongylus are ubiquitous in the studied moose populations. The presence of a single parasite species (e.g., E. alces) in moose individuals was more common than simultaneous infection with E. alces and E. cervi. The prevalence of both E. alces and E. cervi was higher in males than females. The distribution of E. alces and E. cervi prevalence in moose, roe deer, and red deer were in accordance with the membership of a host to a subfamily. Simultaneous occurrences of both Elaphostrongylus species were significantly more frequently noted in red deer fecal samples than those collected from moose or roe deer. Thus, we consider red deer to play a dominant role in sharing of those nematodes to other cervids. Our findings promote applications of molecular methods of identifying parasite species and the assessment of the exchange of parasite community between wild ruminant species in management and health monitoring of game animal populations

The level of habitat patchiness influences movement strategy of moose in Eastern Poland.

Spatio-temporal variation in resource availability leads to a variety of animal movement strategies. In the case of ungulates, temporally unpredictable landscapes are associated with nomadism, while high predictability in the resource distribution favours migratory or sedentary behaviours depending on the spatial and temporal scale of landscape dynamics. As most of the surveys on moose (Alces alces) movement behaviours in Europe have been conducted on Scandinavian populations, little is known about the movement strategies of moose at the southern edge of the species' range. We expected that decreasing habitat patchiness in central Europe would be associated with the prevalence of migratory behaviours. To verify this hypothesis, we analysed 32 moose fitted with GPS collars from two study areas in eastern Poland which differed in a level of habitat patchiness. We classified moose movements using the net squared displacement method. As presumed, lower patchiness in the Biebrza study site was associated with the predominance of individuals migrating short-distance, while in more patchy landscape of Polesie, resident moose dominated. At the individual level, the propensity of moose to migrate decreased with increasing abundance of forest habitats in their summer ranges. In addition, the parameters (migration distance, timing and duration) for migratory individuals varied substantially between individuals and years. Yet, in spring individual moose expressed a consistent migration timing across years. There was little synchronization of migration timing between individuals from the same population both in spring and autumn, which may have been related to mild weather conditions. We observed that moose postponed their migrations and started movement toward summer ranges at a similar time window in years when spring was delayed due to harsh weather. Hence, in light of global warming, we presume further changes in animal movements will arise

Genetic Diversity of Cypripedium calceolus at the Edge and in the Centre of Its Range in Europe

International audienc

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

<p>Abstract</p> <p>Background</p> <p>Climatic 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 (<it>Maculinea arion</it>) 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.</p> <p>Results</p> <p>We sequenced the COI mitochondrial DNA gene (the ‘barcoding gene’) and the EF-1α nuclear gene and found substantial genetic differentiation among <it>M. arion</it> Italian populations in both markers. Eleven mtDNA haplotypes were present in Italy. In contrast, almost no mtDNA polymorphisms was found in the Polish <it>M. arion</it> 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 <it>Wolbachia</it> and our screening suggested 100% prevalence of the bacterium.</p> <p>Conclusions</p> <p>Differences in the genetic structure of <it>M. arion</it> 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 <it>M. arion</it> in Europe. The observed pattern of mtDNA differentiation among the populations could not be explained by an endosymbiotic infection.</p