Structure traits of Longissimus lumborum muscle in wild boar/domestic pig hybrids

The structure of musculus longissimus lumborum (m.l.l.) was evaluated with respect to proportion of three muscle fiber types and their diameters, in gilts and barrows of wild boar/domestic pig hybrids. The experiment was carried out on 29 hybrids (21 barrows and 8 gilts) which originated from crossing Duroc sows with wild boar (Sus scrofa ferus). The diameter of the "red" fibres in barrows was 48.42 microm, significantly greater than in gilts--43.71 microm. The diameters of the remaining two types of fibres in barrows and gilts were similar and amounted to: "intermediate" fibres--39.08 and 40.79 microm, "white" fibres--51.42 and 51.03, respectively. In respect to sex no statistical differences in proportion of any types of fibers were found, which in barrows came to: "red"--12.93%, "intermediate"--30.17% and "white"--57.32%, and in gilts to: 12.50, 27.04 and 60.45%, respectively. In conclusion, in m.l.l. of wild boar/domestic pig hybrids, smaller diameters of all muscle fibers types were identified as well as a higher proportion of intermediate fibers in comparison to m.l.l. of various pig breeds. An increased proportion of the intermediate fibers probably results from the interaction between factors such as age (8-months), physical activity (open-air for running) and the influence of wild boar genes.     

High hunting pressure selects for earlier birth date: wild boar as a case study

Exploitation by humans affects the size and structure of populations. This has evolutionary and demographic consequences that have typically being studied independent of one another. We here applied a framework recently developed applying quantitative tools from population ecology and selection gradient analysis to quantify the selection on a quantitative trait-birth date-through its association with multiple fitness components. From the long-term monitoring (22 years) of a wild boar (Sus scrofa scrofa) population subject to markedly increasing hunting pressure, we found that birth dates have advanced by up to 12 days throughout the study period. During the period of low hunting pressure, there was no detectable selection. However, during the period of high hunting pressure, the selection gradient linking breeding probability in the first year of life to birth date was negative, supporting current life-history theory predicting selection for early births to reproduce within the first year of life with increasing adult mortality.     

Genetic diversity in the European wild boar Sus scrofa: phylogeography,population structure and wild x domestic hybridization

• 1 Despite the vast literature on genetic variation in the domestic pig Sus scrofa, little is known about genetic differentiation in wild boar populations.
• 2 Here we present an up‐to‐date review of published data on the past and recent history of the European wild boar, its genetic diversity and the spatial distribution of genetic variation throughout the continent.
• 3 The phylogeography of the species seems to be shaped mostly by past large‐scale events (like postglacial recolonization) rather than by more recent human manipulation. Genetic differentiation is observed both on a continental and a regional scale, and non‐intuitive barriers to gene flow occur.
• 4 From an indirect estimate, hybridization between wild boar and domestic pigs is seemingly a minor source of genetic variation for wild boar populations, yet risks are still linked to the release of captive hybrids in some areas.
• 5 Finally, we present future perspectives concerning the development of powerful molecular tools and their possible application to the study and management of this species.

     

Frequency of chromosomes carrying endogenous retroviruses in the populations of domestic pig and wild boar

Statistical analysis of the frequency of chromosomes carrying three types (A, B, and C) of porcine endogenous retroviruses (PERV) was based on molecular-genetic testing of populations of domestic pigs and wild boars. Domestic pigs were shown to have higher frequency of PERV and haplotypes containing two and three types of PERV than wild boars.     

Novel Y‐chromosome short tandem repeats in Sus scrofa and their variation in European wild boar and domestic pig populations

Y‐chromosome markers are important tools for studying male‐specific gene flow within and between populations, hybridization patterns and kinship. However, their use in non‐human mammals is often hampered by the lack of Y‐specific polymorphic markers. We identified new male‐specific short tandem repeats (STRs) in Sus scrofa using the available genome sequence. We selected four polymorphic loci (5–10 alleles per locus), falling in one duplicated and two single‐copy regions. A total of 32 haplotypes were found by screening 211 individuals from eight wild boar populations across Europe and five domestic pig populations. European wild boar were characterized by significantly higher levels of haplotype diversity compared to European domestic pigs (H_D = 0.904 ± 0.011 and H_D = 0.491 ± 0.077 respectively). Relationships among STR haplotypes were investigated by combining them with single nucleotide polymorphisms at two linked genes (AMELY and UTY) in a network analysis. A differentiation between wild and domestic populations was observed (F_ST = 0.229), with commercial breeds sharing no Y haplotype with the sampled wild boar. Similarly, a certain degree of geographic differentiation was observed across Europe, with a number of local private haplotypes and high diversity in northern populations. The described Y‐chromosome markers can be useful to track male inheritance and gene flow in wild and domestic populations, promising to provide insights into evolutionary and population genetics in Sus scrofa.     

Chromosome R-banding patterns and NOR homologies in the European wild pig and four breeds of domestic pig

Four European wild pigs and 27 domestic pigs were studied; three Landrace, 12 village pigs from Papua New Guinea, two Chinese pigs Meishan and 10 Creole pigs from the French Antilles. The R-banding patterns were identical for all domestic breeds despite their different history and geographical divergence. The European wild pigs showed a similar R-banding pattern and a centric fusion between pairs 15 and 17 (2n = 36). The nucleolar organizers (NORs) in the European wild pig and the four domestic breeds were localized on the secondary constriction of chromosomes 8 and 10. All animals exhibited in the majority of metaphases two NORs on both chromosomes 10. In some animals. the NORs were expressed only in one of the homologs of chromosome 8. The Chinese pigs had a high amount of silver precipitates on two homologs of chromosome 8. This study confirms several previous reports on the polymorphism of NOR patterns in different domestic pig breeds.     

Hunters serving the ecosystem: the contribution of recreational hunting to wild boar population control

The extractive nature of recreational hunting may provide a service to both the ecosystem and society, namely the control of problem species. We reviewed the annual wild boar hunting bag data from hunting sites in Asturias (Spain) from 2000/01 to 2013/14, paying particular attention to the evolution on hunting estates after ban periods. We hypothesized that the annual hunting bag after a hunting ban would be larger than that of the pre-ban period, and that this difference could provide an indication of hunters’ relative contribution to wild boar population regulation. The total hunting bag grew during the study period, from 3723 wild boar (0.39ind/km²) in the 2000/01 hunting year to 7593 in that of 2013/14 (0.79ind/km²)—a mean annual increase of 5.63%. Low hunting quotas cannot be blamed for these growing trends, since no more than 50% of the authorized animals are hunted. The growth of the mean annual pre-ban hunting bag on the estates on which hunting bans took place was 8.46%. The hunting bag grew by 40.33% immediately after the hunting ban ended—a growth rate seven times higher than that of the background hunting bag. This constitutes a proxy of the regulatory effect of hunters on wild boar population growth. Following the remarkable increase after the ban, the wild boar hunting bag attained values that were slightly lower than those of the pre-ban period, which indicates that hunters are able to reduce wild boar abundance. Hunting, therefore, provides an important service to both the ecosystem and society by contributing to regulating the growth of problem species such as the wild boar.     

The failure of the introduction of wild boar Sus scrofa in the island of Cyprus: a case study

Wild boar (Sus scrofa L.) were introduced in the island of Cyprus in 1990, when five animals were imported from Greece for game farming. In 1994, wild boars were illegally released in Lemesos (Limassol) Forest and in 1996 in the Troodos National Forest Park. Soon the population increased and dispersed throughout the park. In 1997, the government of Cyprus decided to eradicate wild boar because of the danger of transmitting diseases to livestock and to prevent possible environmental destruction. To control the wild boar, hunting was permitted and game wardens were instructed to eliminate the free-ranging animals. In 2004, no animals were observed in localities where they had been seen before. Surveys in September 2004 (Troodos National Park) and January/February 2005 (Troodos Forest, Pafos Forest, and Lemesos Forest) revealed no signs of recent wild boar presence. The reasons for the possible failure of wild boar to establish in Cyprus are discussed.     

Seroprevalence of six reproductive pathogens in European wild boar (Sus scrofa) from Spain: the effect on wild boar female reproductive performance

We studied the seroprevalence of six reproductive pathogens in Spanish hunter-harvested wild boar females. The sample was representative of the hunting harvest in the studied hunting estates. Mean antibody prevalences were: 60.6+/-0.06% for Aujeszky's disease virus (ADV), 56.6+/-0.09% for porcine parvovirus (PPV), 51.8+/-0.06% for porcine circovirus type 2 (PCV2), 29.7+/-0.09% for Brucella spp. and 36.3+/-0.1% for Toxoplasma gondii. We did not detect antibodies against porcine reproductive and respiratory syndrome virus (PRRSv). ADV seroprevalence was associated with PPV and PCV2 seroprevalence in Spanish wild boar females. Ovulation rate in the studied wild boar females was 4.41+/-0.16 (n=120), mean litter size was 3.91+/-0.16 (n=82) and the partial resorption index 0.92+/-0.17 (n=66). Ovulation rate and litter size were statistically associated with age. T. gondii seroprevalence was negatively related to ovulation rate and partial resorption index. Wild boars from managed fenced estates had antibodies against more pathogens than wild boars from open estates. Potential relations between management of wild boar populations and exposure of individuals to different reproductive pathogens are discussed.     

Sex effect on habitat selection in response to hunting disturbance: the study of wild boar

Spatial variation of the ‘predation risk’ due to human activities or distribution may increase the sexual difference in habitat selection. Indeed, females with offspring are usually more risk adverse than males. Based on a long-term wild boar study, we analysed the diurnal distribution of female and male wild boar before, during and after the hunting period. Hunting, food and foliation were investigated as factors affecting patterns of forest parcel selection. As expected, dense vegetative covers were selected during resting periods, but wild boar decreased this pattern of habitat selection in response to hunting disturbance. Moreover, the habitat selection of wild boar did not fit with the variation of food availability (presence or absence of mast) and the vegetation cycle. As expected, sows responded more to the hunting disturbance than males, leading to a more pronounced sexual difference during the riskier season. The unexpected decrease of bush use may be explained either by the increased hunting effort in this habitat or by the increased movements between resting sites due to disturbance, leading to a more random habitat selection pattern. The observed difference between sexes could result from a higher response of females with offspring to hunting, leading to an increased frequentation of secondary habitats, whereas males can tolerate more risks and remain hidden in thicket plots. Our results highlight how hunting disturbance can lead game species to change their patterns of refuge habitat selection and may affect the habitat segregation between the sexes.     

Reproductive allocation in pulsed-resource environments: a comparative study in two populations of wild boar

Pulsed resources influence the demography and evolution of consumer populations and, by cascading effect, the dynamics of the entire community. Mast seeding provides a case study for exploring the evolution of life history traits of consumers in fluctuating environments. Wild boar (Sus scrofa) population dynamics is related to seed availability (acorns/beechnuts). From a long-term monitoring of two populations subjected to markedly different environmental contexts (i.e., both low vs. high frequency of pulsed resources and low vs. high hunting pressure in Italy and in France, respectively), we assessed how pulsed resources shape the reproductive output of females. Using path analyses, we showed that in both populations, abundant seed availability increases body mass and both the absolute and the relative (to body mass) allocation to reproduction through higher fertility. In the Italian population, females equally relied on past and current resources for reproduction and ranked at an intermediate position along the capital-income continuum of breeding tactics. In contrast, in the French population, females relied on current more than past resources and ranked closer to the income end of the continuum. In the French population, one-year old females born in acorn-mast years were heavier and had larger litter size than females born in beechnut-mast years. In addition to the quantity, the type of resources (acorns/beechnuts) has to be accounted for to assess reliably how females allocate resources to reproduction. Our findings highlight a high plasticity in breeding tactics in wild boar females and provide new insight on allocation strategies in fluctuating environments.     

Segmental aplasia in the uterus of a European wild pig (Sus scrofa)

This paper reports an instance of aplasia in the uterine horn of the European wild pig (Sus scrofa).     

Lepidoptera Papilionoidea communities as a sentinel of biodiversity threat: the case of wild boar rooting in a Mediterranean habitat

Butterfly communities can be modified by the activities of large mammals. The wild boar (Sus scrofa) is one of the most common mammals in Europe and has notably expanded its distribution range in recent decades. The present work aimed to investigate the possible effect of wild boar rooting activity on butterflies in olive groves inside the “Cilento, Vallo di Diano and Alburni” National Park. Butterflies were surveyed in five Rooted (R) and five Control areas (C). Transects were made from April to September in 2011 and 2012. Forty-three species and 3659 individuals were found, of which 39 species and 2426 individuals were detected in C areas and 31 species and 1233 individuals in R areas. A community-level approach showed a significantly higher abundance, richness and Shannon–Wiener index in C than in R. An ecological-level approach indicated that more specialised butterflies were significantly more affected by wild boar activity. Finally, the response of single species was investigated: two species (Colias croceus and Polyommatus icarus) were significantly more represented in R, whereas six species (Aricia agestis, Hipparchia statilinus, Lasiommata megera, Melanargia arge, Pyronia cecilia and Thymelicus acteon) were significantly more abundant in C. Three species considered at risk (M. arge; Annex II of Directive 92/43/EEC; H. statilinus and T. acteon: European Red List) were less represented in rooted areas. Overall, the intensive wild boar activity negatively correlated with butterflies in the olive groves studied.     

Reduction of flobufen in pig hepatocytes: effect of pig breed (domestic,wild) and castration

Knowledge of the biotransformation processes of veterinary drugs and food supplements in food-producing animals is increasingly important. Residual levels of parent compounds or their metabolites in food of animal origin may differ with the breed, breeding conditions, and gender of animals. The nonsteroidal antiinflammatory drug flobufen, 4-(2',4'-difluorobiphenyl-4-yl)-2-methyl-4-oxobutanoic acid (racemic or its individual enantiomers) was used as a model to evaluate differences in activity, stereoselectivity, and stereospecificity of reductases in primary cultures of hepatocytes from intact male or castrated male domestic pigs (Sus scrofa domestica) or male wild pig (Sus scrofa scrofa). Time-dependent consumption of flobufen enantiomers and formation of dihydroflobufen (DHF) diastereoisomers as their principal metabolites in hepatocytes were measured using chiral HPLC. Flobufen reduction in hepatocytes from all three experimental groups of animals was stereoselective ((+)-R-flobufen was predominantly metabolized) and stereospecific (2R;4S-DHF and 2S;4S-DHF diastereoisomers were preferentially formed). Flobufen reductases activity in male domestic pigs was 30 times higher compared to castrated pigs. Flobufen reductases activity was similar in domestic and wild pigs. The stereospecificity and stereoselectivity of DHF production did not significantly differ with breed or castration of animal. Chiral inversion of flobufen enantiomers was also studied and differences between castrated and intact male pigs were seen.     

Dispersal of freshwater invertebrates by large terrestrial mammals: a case study with wild boar (Sus scrofa) in Mediterranean wetlands

1. Many invertebrates inhabiting insular aquatic habitats rely on external agents or vectors to disperse. Besides water connections and wind, waterfowl and amphibians are known to mediate passive dispersal of freshwater invertebrates. However, the possibility of dispersal by terrestrial mammals has been largely overlooked. 2. We investigated the potential of both external and internal zoochorous dispersal of aquatic invertebrates by the wild boar (Sus scrofa) in Mediterranean wetlands in the Camargue (France). As wild boar frequently visit wetlands for feeding and wallowing purposes, we hypothesized that they may be important passive dispersal vectors of aquatic invertebrates at a local scale. Dried mud was collected from selected ‘rubbing trees’ used by boars to dispose of parasites. Additionally, faecal pellets were collected from different locations in the wetland area. 3. Seventeen freshwater invertebrate taxa including rotifers, cladocerans, copepods and ostracods hatched from sediment obtained from ‘rubbing trees’, while invertebrates hatching from dried faeces (10 taxa) were mainly rotifers. Dispersing invertebrates were collected up to 318 m from a nearest potential dispersal source. Both abundance and richness of invertebrates significantly decreased with dispersal distance. 4. Our results demonstrate that large mammals such as wild boar can act as dispersal vectors of aquatic invertebrates at a local scale in the wetland area of the Camargue and suggest that external transport may be quantitatively more important than internal transport. As wallowing (mud bathing) is common in many terrestrial mammals, this mode of dispersal may be quite widespread.     

A non-pollen palynomorphs contribution to the local environmental history in the Ligurian Apennines: a preliminary study

As part of a regional research project on wetlands, a analysis was carried out on non pollen palynomorphs (NPP) from the upper sediments of a mountain peat bog in the Ligurian Apennines, northwest Italy. The aim of this project was to see if NPPs could yield useful results on local ecology and human activity in connection with the use of resources. More than 60 NPP types were found, among which a new type is described. A good agreement was observed between pollen assemblages and different NPP types, which are still an under-exploited source of information. Coprophilous fungi suggest the presence of livestock at the site after cal. a.d. 770–1160, while various algae and other water-demanding organisms show an increasing eutrophication of the environment in the most recent phase after cal. a.d. 1500. This approach, which is new for this region, confirms the hypothesis that local farming practices, such as management of pasture and woodland, were not recently established here. The site features and both NPP variety and significance show that further improvement of this additional tool could contribute to answering some questions about past cultural landscapes.