Genetic structure of the wild boar population in Portugal: Evidence of a recent bottleneck

The present study assesses the degree of genetic structure and the presence of recent genetic bottlenecks in the wild boar population in Portugal. One hundred and ten individuals were sampled after capture during organised legal drive hunts, conducted in 58 municipalities across the continental territory, during the game seasons of 2002/2003 and 2003/2004. Individuals were genetically typed at six microsatellite loci using multiplex PCR amplification. Significant deviations from Hardy–Weinberg equilibrium were found for the total population of wild boar in Portugal. Wild boar population genetic structure was assessed using Bayesian methods, suggesting the existence of three subpopulations (North, Centre and South). Tests were conducted to detect the presence of potential migrants and hybrids between subpopulations. After exclusion of these individuals, three sets of wild boars representative of respective subpopulations were distinguished and tested for the effects of recent bottlenecks. Genetic distances between pairs of subpopulations were quantified using F_ST and R_ST estimators, revealing a variation of 0.138–0.178 and 0.107–0.198, respectively. On the basis of genetic and distribution data for Portuguese wild boar from the beginning of the 20th century, a model of strong demographic decline and contraction to isolated refuge areas at the national level, followed by a recovery and expansion towards former distribution limits is suggested. Some evidence points to present admixture among subpopulations in contact areas.     

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.     

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.     

Udder preference in wild boar piglets

Competition to access the front teats in the domestic pig is strong during the first days of life, despite the fact that the number of piglets is fewer than the number of teats. Preference has been explained in terms of greater milk production (although it might also be the consequence rather than the cause), or reduced risk of crushing when the female lies down to begin a suckling session. Here, with the aim of determining whether one cause might be the body and reproductive modifications caused by artificial breeding, we analysed teat preferences of wild boar piglets in the wild. Fifty-one hunted females in lactation in the Western Iberian Peninsula were analysed. In contrast to domestic pigs, wild boar piglets showed a clear preference for rear udders. This preference was consistent for females of different ages and body characteristics, as well as for females hunted in different seasons. We suggest that the choice of rear udders in the wild boar may be related to the advantages of suckling at places offering higher protection from low temperatures and from predators, in contrast to domestic pigs, for which crushing is the main cause of mortality.     

Tuberculous meningoencephalitis in a wild boar

Bovine tuberculosis, caused by Mycobacterium bovis, is a zoonotic disease that affects cattle and wildlife worldwide. These animal hosts can serve as reservoirs of infection, thus increasing the risk of human exposure and infection. Tuberculous meningoencephalitis complicating disseminated tuberculosis is described in a 7-mo-old wild boar (Sus scrofa).     

Helminths of wild boar in Spain.

Forty-seven wild boars (Sus scrofa) collected from two areas in the province of Valencia (eastern Spain) were examined for digestive and respiratory helminth parasites. Helminth species and their prevalence were Taenia hydatigena cysticercus (19%), Ascarops strongylina (87%), Physocephalus sexalatus (6%), Ascaris suum (2%), Metastrongylus spp. (85%), Capillaria sp. (2%) and Macracanthorhynchus hirudinaceus (21%). Trichinella spp. were not found. Physocephalus sexalatus, A. suum, Capillaria sp. and M. hirudinaceus were found only in wild boars collected from one area (National Hunting Reserve of Cortes de Pallás). Macracanthorhynchus hirudinaceus did not occur in hogs < 1-yr-old, whereas the intensity of Metastrongylus spp. infection was the greatest in this age group.     

The wild boar of Egypt]

The wild boar, Sus scrofa, is not a typical member of the Egyptian wild fauna, although it appears to have lived in the Nile Delta and other suitable regions in the north of the country. However, historic populations were probably of mixed origin, including feral domestic pigs. It is incorrect, as is sometimes still done, to include the wild boar in the iconographic bestiary of Ancient Egypt and assume that the domestic pigs of Ancient Egypt derive from local wild boars.     

Reproductive performance of swine females re-serviced after return to estrus or abortion

The objective of this study was to analyze reproductive performance in swine females re-serviced after return to estrus or abortion in comparison with females in first service (gilts or weaned females). Records used were obtained from four commercial sow herds in Brazil including 24,194 mating records from PigCHAMP research database. Three mating categories (first service in gilts or weaned sows, re-serviced after return to estrus and re-serviced after abortion) were considered for the analysis. The farrowing rate (FR) was less and return to estrus (RER), abortion rate (ABR) and total born (TB) were greater in the category re-serviced after return to estrus compared to first service category (P<0.05). The category re-serviced after abortion only differed from the first service category by a greater ABR (P<0.05). In gilts and PO2-5 females re-serviced after a return to estrus, the FR was less (72.0% and 83.2%) and RER was greater (22.3% and 12.5%) compared to first service PO2-5 sows (92.7% and 5.3%; P<0.05). A re-service after a return to estrus did not affect TB in PO > or =2 females (P>0.05) but resulted in less TB in gilts and greater TB in primiparous sows (P<0.05). In females re-serviced after a return to estrus the performance was similar (P>0.05) between the two intervals considered as regular return to estrus (18-24 days and 36-48 days). Among the intervals considered as irregular return to estrus, greater FR was observed in intermediate (25-35 days) than in early (11-17 days) or late (>48 days) intervals. The re-service after a return to estrus results in an impaired farrowing rate, with a greater impact on gilts than at older parities. Females re-serviced after abortion are more predisposed to the recurrence of this reproductive failure.     

Reproductive performance of Common Goldeneye Bucephala clangula females in relation to age and lifespan

We studied the effects of female age and length of lifespan on reproductive performance in the Common Goldeneye Bucephala clangula , a precocial species with self-feeding chicks. Dependent variables studied were the occurrence of failed nesting attempts and non-breeding years, clutch size, nesting and hatching success, female condition and recovery rate of offspring. To avoid misinterpretations resulting from age-dependent quality changes in the cohorts, individuals with different lifespans were separated in the analyses. There was no evidence that females of different lifespan differed in reproductive strategy. The data revealed no significant differences in nest losses, occurrence of non-breeding years, timing of nesting or clutch size, but the physiological condition of short-lived females was poorer than that of longer living females. This accords with the prediction that poor-quality females invest proportionally more in reproduction than high-quality females and consequently die earlier. The most productive individuals were those that lived longest. The only indication of senescence was the low recovery rate of offspring produced by old females. The last breeding attempt did not differ in any observable respect from the penultimate attempt, implying that the last investment in reproduction was no heavier than the previous one.     

Reproductive performance of a transgenic boar carrying the bovine growth hormone gene (bGH)

The aim of this study was to obtain information on the possible influence of the bovine growth hormone gene (bGH) on gametogenesis and reproductive parameters of a 2-year-old Polish Landrace transgenic boar. The bGH gene construct had been introduced into the zygote of the boar with the use of the microinjection technique. On the basis of the available documentation we established that the fertility of the investigated transgenic (bGH) boar was low in comparison with other animals of the Polish Landrace breed, with a poor libido, ineffective matings and, on average, 3 live piglets less per litter. Samples of testis tissue from the boar were obtained after castration. In total, we observed 100 spermatocytes and all of them had normally paired bivalents. It is possible that the boar's lower fertility was caused by some, as yet unknown factor.     

Importance of the wild boar in the epidemiology of wild trichinellosis in Piedmont and Liguria

Muscle samples from 1,508 wild boars (Sus scrofa) harvested in Piedmont and Liguria between 1987 and 1990 were examined for larvae of Trichinella sp. by trichinelloscopy and peptic digestion. No wild boar was infected, though trichinellosis was present in foxes (Vulpes vulpes) from the same areas (14 positives out of 608) with the highest prevalence in the mountain range (25.0%). Infection was also not found in 40 stone martens, 5 badgers and 3 stoats. Five vulpine isolates were identified as belonging to T3 zymodeme. These results show that free-ranging wild boars, although being a source of trichinellosis infection for man in Italy (9.2% of the 584 cases diagnosed since 1961), have no significance in maintaining the sylvatic cycle of this parasite in the study area. The data agree with the low infectivity of Italian strains of fox origin for swine seen in the experimental infections carried out so far.     

Pseudorabies virus in European wild boar from central Italy

Tissue and blood samples were collected from 152 wild boars (Sus scrofa) from the Maremma area (Grosseto district, Central Italy) between November 2002 and January 2003. The presence of pseudorabies virus (PRV) antibodies, antigen, and DNA were confirmed by an enzyme-linked immunosorbent assay (ELISA), immunohistochemistry, and polymerase chain reaction (PCR), respectively. Of 152 animals, 62 (41%) were positive for viral antigen in tonsillar tissue. Of the 80 serum samples that were suitable for testing, 41 (51%) were positive for PRV antibodies. Positive immunohistochemistry results were confirmed by PCR. A significantly higher prevalence of PRV antigen and seroprevalence was detected in older animals. No differences were detected between males and females or for animals coming from different areas sampled. Results confirm that PRV is endemic in this wild boar population with a high prevalence of infection. The results of immunohistochemistry investigations demonstrated that a large number of wild boars harbor PRV in tonsillar tissues and should be considered as an important reservoir of PRV.     

Fluctuating food resources influence developmental plasticity in wild boar

To maximize long-term average reproductive success, individuals can diversify the phenotypes of offspring produced within a reproductive event by displaying the ‘coin-flipping’ tactic. Wild boar (Sus scrofa scrofa) females have been reported to adopt this tactic. However, whether the magnitude of developmental plasticity within a litter depends on stochasticity in food resources has not been yet investigated. From long-term monitoring, we found that juvenile females produced similar-sized fetuses within a litter independent of food availability. By contrast, adult females adjusted their relative allocation to littermates to the amount of food resources, by providing a similar allocation to all littermates in years of poor food resources but producing highly diversified offspring phenotypes within a litter in years of abundant food resources. By minimizing sibling rivalry, such a plastic reproductive tactic allows adult wild boar females to maximize the number of littermates for a given breeding event.     

Reproductive biology and success of invasive Australian acacias in Portugal

Reproductive traits are crucial for the establishment and maintenance of populations in new areas, and therefore for the invasion process. This work aimed to study the reproductive biology of four aggressive invasive Australian Acacia spp. in Portugal. Fruit and seed set, seed weight and germinability, and seedling growth were assessed for self‐ and outcross treatments in invasive populations of A. dealbata, A. longifolia, A. melanoxylon and A. saligna. Acacia spp. showed different investments in the production of reproductive units and in natural reproductive success, with A. dealbata, the most aggressive species, having the highest investment and reproductive success. Acacia melanoxylon showed a different reproductive strategy, andromonoecy, contrasting with the other hermaphroditic species. Acacia spp. were shown to be predominantly self‐incompatible, but a low level of spontaneous selfing enabled the production of viable offspring. Acacia dealbata and A. longifolia suffered pollen limitation. Self‐progeny had lower viability than progeny from outcrossing for A. dealbata and A. melanoxylon. Acacia spp. did not show higher compatibility rates in comparison with the native area. They had low fruit set but, as a result of their massive flower production, their realized reproductive success was high and could have contributed to the invasion. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174 , 574–588.