东北亚地区野猪种群mtDNA遗传结构及系统地理发生

研究测定了中国东北、华北及四川西部72个野猪(Susscrofa)个体线粒体控制区全序列,并结合GenBank报道的日本野猪(S.s.leucomystax)、琉球野猪(S.s.riukiuanus)72个同源区序列,分析了东北亚地区野猪线粒体DNA的变异及系统地理格局。在东北亚地区野猪的线粒体控制区共发现42个变异位点,均为转换,共定义了34个单元型。单元型之间的系统发生分析表明,东北亚地区野猪来自同一祖先。东北亚地区野猪现生种群具有显著的种群遗传结构,其中日本野猪与分布于中国东北地区的东北野猪之间亲缘关系较近;而琉球野猪则与华北野猪间亲缘关系较近,与日本野猪和东北野猪间的关系相对较远。嵌套进化枝系统地理分析(Nestedcladephylogeographicalanalysis,NCPA)表明:东北亚地区野猪由同一祖先经过长距离的迁徙而形成现生各种群(或亚种);琉球野猪应起源于大陆野猪,其种群演化可能经历了片断化事件;华北野猪呈现南部种群遗传多样性高的特点,其种群内部曾经历了一次分布区由南向北的扩张     

Prehistoric Sado Island populations of Sus scrofa distinguished from contemporary Japanese wild boar by ancient mitochondrial DNA

Ancient mitochondrial DNA (mtDNA) mainly from Jomon Period Sus scrofa bone specimens (6,100-1,700 years old) was examined to clarify the genetic relationships between prehistoric and contemporary S. scrofa on Hokkaido, Honshu, Sado, and Izu islands of the Japanese Archipelago. Phylogenetic analysis of the mtDNA control region (574 bp) and analysis of pairwise nucleotide differences between prehistoric and contemporary S. scrofa sequences showed the following relationships between these groups: (1) a group genetically similar to contemporary Japanese wild boars was found mainly on Honshu Island, Hokkaido Island, and the Izu Islands, and (2) a monophyletic group distinct from contemporary Japanese wild boars was found on Sado Island. These results suggest that prehistoric people introduced S. scrofa from Honshu Island to Hokkaido Island and the Izu Islands. The estimated divergence times between the prehistoric Sado group and the other prehistoric S. scrofa is approximately congruent with the geological isolation of Sado Island from Honshu Island. Our results suggest that this extinct S. scrofa population was present on Sado Island as recently as around 2,000 years ago.     

Grouping-patterns and inter-group relationships of Japanese wild boars (Sus scrofa leucomystax) in the Rokko mountain area

Grouping-patterns and inter-group relationships of Japanese wild boars (Sus scrofa leucomystax) were studied at a provisioning site in the Rokko mountain area, Hyogo Prefecture, Japan, from 1982 to 1983. The observations were divided into four study periods. Almost all wild boars were individually identified and their kin-relationships were followed from the beginning of the study. To examine grouping-patterns of Japanese wild boars, the degree of association between any two individuals, based on coexisting time at the provisioning site, was analyzed for each study period. Mother and her litter group (MLG), female littermate group (FLG) and solitary individual were recognized grouping-patterns. Groups did not associate with each other. Male offspring separated from their mother before 1 year of age and become solitary. Separation of female offspring occurred before the subsequent parturition of their mother. The proximate cause of separation was increased aggression by the mother. After separation, female offspring formed a FLG. However, the FLG seemed to be generally a temporary one, maintaining its stability only until parturition of it's members. Thereafter adult females had no close association with any other individuals, except for their own infants. Male offspring disappeared from their natal area, while female offspring could remain there.     

Genetic variation in isozymes of wild boar (Sus scrofa ferus Linné)

Eleven isozyme systems were investigated in wild boar (Sus scrofa ferus L.) by means of horizontal starch gel-electrophoresis using liver and kidney extracts. Samples of 103 specimen that originated from three adjunct localities from Rhineland-Palatinate (Fed. Rep. Germany) were analysed. AAT, ACO, GDH, GPDH, LDH, ME, MPI, MR, PGDH, and PGI were invariant. Genetic polymorphism is described for PGM. The genetic polymorphism at Pgm2 is explained by a biallelic model. Observed genotypic structure did not differ significantly from Hardy-Wein-berg-proportions at this gene locus. The degree of heterozygosity is 58,3 % and Wright's Fixation Index F =–0.166 at Pgm2. The allelic structure at this gene locus differed to a great extent from that found in domestic swine, i. e. in domestic swine the faster migrating Pgm2 allozyme was only found in relative low frequencies compared to wild boar. The genetic polymorphisms were moderate in the wild boar population compared to electrophoretic data of other animal species.     

Estimation of the fertility rates of Japanese wild boars (Sus scrofa leucomystax) using fetuses and corpora albicans

Effective population control of Japanese wild boar (Sus scrofa leucomystax) requires reliable information about population dynamics. Fertility rate is the fundamental component of reproduction to evaluate population dynamics. However, little is known regarding the fertility rate of Japanese wild boar. The traditional hunting practices make it difficult to obtain pregnant females and calculate the fertility rate by checking fetuses as is performed in other countries. Therefore, we focused on the corpora albicans (CA) as the CA remains in the ovaries of postpartum females after pregnancy. This study aimed to evaluate the utility of CA and estimate the fertility rate of Japanese wild boars using CA. Histological analysis of ovaries enabled us to discriminate type 1 CA, which remains for 1 year after breeding. Type 1 CA is a superior indicator compared with lactation in the non-pregnancy season because it allows verification of postpartum females over a long period. The fertility rate was calculated by the combination of pregnant and postpartum females using fetuses and type 1 CA from April to November. The fertility rate of the females captured after the second pregnancy season was 90.3 % during the pregnancy period and 100 % during the non-pregnancy period. The high fertility rate of adult females suggests that intensive adult female harvesting is needed. Our new method to determine fertility rates contributes to developing a monitoring system to adequately control Japanese wild boar population.     

Craniometrical analysis of Bulgarian wild boar (Sus scrofa) populations

Skull characters of wild boars ( Sus scrofa L.) from four regions of Bulgaria were compared using stepwise discriminant, cluster of cases and principal component analyses (PCA). Classification functions were derived for discriminating individuals from different areas. Specimens from the north-eastern part of the country (Dobrudja and the Balkan Range) were found well separated from those from the south (Rila-Rhodopes & Strandja Mountains). PCA showed the differences being mostly related to the size rather than to the shape of both the cranium and the mandible. Natural migrations, intergradation areas between different subspecies, as well as restocking and hybridization with semi-domestic pigs are discussed as possible factors influencing the solution of the problem of the intraspecific systematics of the wild boar in Bulgaria.     

Daily selection of habitat in wild boar (Sus scrofa)

Spatial segregation of the sexes is observed in numerous species of ungulates, but are there other forms of segregation in species where spatial segregation is not present, such as in the wild boar? This study investigates the differences in habitat selection between two categories of individuals whose ecological requirements are supposedly divergent: subadult males, and females with dependent piglets. The proportion of the day spent in each category of habitat was used as a parameter representative of daily decisions. The overall results fit with the hypothesis that females with piglets avoid insecure habitats, and that both categories select habitats on the basis of food richness. In addition, it was found that the pattern of habitat selection depends on the total time spent moving slowly. A short duration of slow movement was observed only in males, but the time dedicated to efficient foraging (in rich habitats) was sufficient in all observations of all animals. Subadult males, therefore, do not differ from each other in foraging efficiency, but in the time spent on slow movement in secure habitats. Those spending more time active in secure habitats have the opportunity of performing more potentially beneficial activities such as social interactions and sexual contacts.     

Genetic characterization and phylogeography of the wild boar Sus scrofa introduced into Uruguay

The European wild boar Sus scrofa was first introduced into Uruguay, in southern South America during the early decades of the last century. Subsequently, and starting from founder populations, its range spread throughout the country and into the neighbouring Brazilian state Rio Grande do Sul. Due to the subsequent negative impact, it was officially declared a national pest. The main aim in the present study was to provide a more comprehensive scenario of wild boar differentiation in Uruguay, by using mtDNA markers to access the genetic characterization of populations at present undergoing rapid expansion. A high level of haplotype diversity, intermediate levels of nucleotide diversity and considerable population differentiation, were detected among sampled localities throughout major watercourses and catchment dams countrywide. Phylogenetic analysis revealed the existence of two different phylogroups, thereby reflecting two deliberate introduction events forming distantly genetic lineages in local wild boar populations. Our analysis lends support to the hypothesis that the invasive potential of populations emerge from introgressive hybridization with domestic pigs. On taking into account the appreciable differentiation and reduced migration between locales in wild boar populations, management strategies could be effective if each population were to be considered as a single management unit.     

Helminth parasites of wild boar, Sus scrofa, in Iran.

Fifty-seven wild boars (Sus scrofa) from protected regions of Iran were examined for helminths. Sixteen species of helminths were collected; there were ten nematodes, one acanthocephalan, two trematodes and three larval cestodes. New host and distribution records were established for all helminths except of Taenia solium cysticerci. Wild boar shared nine of these helminths with domestic pigs, six with ruminants and three with human beings in Iran. Metastrongylus pudendotectus and M. salmi are reported for the first time from Iran.     

Electrophoretic polymorphism of erythrocyte leucine aminopeptidase in the wild boar, Sus scrofa

An erythrocyte leucine aminopeptidase (Rbc LAP) electrophoretic polymorphism was detected in Italian wild boars, Sus scrofa. Such a polymorphism has not previously been reported in the domestic pig. It is suggested that this locus could be a marker for genetic differences between the domestic and the wild forms of Sus scrofa.     

Mortality rates of wild boar Sus scrofa L. in central Europe

In many parts of Europe, wild boar Sus scrofa population increase, and thus, high densities and dispersal into new areas are accompanied by economic problems. Due to many factors like insufficient hunting strategies as well as underestimation of population densities and reproduction rates, harvest rates seem to be insufficient. Thus, we calculated mortality rates of several wild boar populations from 1998 to 2009, to show the efficiency of hunting within several studies distributed over eight European states. For calculating mortality rates, the daily probability of survival of radio telemetrically observed wild boar was analysed according to Mayfield (Wilson Bull 73:255-261, 1961) and with survival analysis in R for three age classes (0, 1, ≥2 years) and both sexes. The mortality rates of wild boar per annum, especially piglets, were comparably low (about 0.5 for piglets and similar for total population). About three third of all observed animals survived at least until the next period of reproduction. Mortality rates differed between some study areas, the sexes and age classes. The sex ratio of the shot piglets equals the sex ratio of captured piglets; there seems to be no sex-biased hunting in this age class, but in an older age. Shooting was the main cause of death; only very few animals died by natural causes, e.g. diseases. The comparative analysis of all studies reflects a low mortality of wild boar in highly productive populations. Our results certified the findings of several studies that predation, natural mortality, and road mortality have only small impact on wild boar populations, whereas especially, nutrition or hunting are mainly decisive. Assuming net reproduction rates of more than 200 % according to literature data, our results indicate that harvest rates are not sufficient at our study sites. In all our studies, mortality rates and, thus, harvest rates are less than the assumed total net reproduction. Especially, the harvest rate of piglets seems to be insufficient. Thus, the population will increase further. High reproduction has to be counteracted by regulating mainly the reproductive animals. For regulating a population, combined and effective hunting methods have to be conducted to harvest at least the net reproduction. Thus, we recommend higher hunting rates of piglets (80 % of the offspring should be harvested) and of adult females. Intensified hunting of piglets by drive hunts and at an early age as well as intensified single hunt on adult females might help regulating wild boar populations.     

Electrophoretic polymorphism of erythrocyte leucine aminopeptidase in the wild boar, Sus scrofa

Summary. An erythrocyte leucine aminopeptidase (Rbc LAP) electrophoretic polymorphism was detected in Italian wild boars, Sus scrofa. Such a polymorphism has not previously been reported in the domestic pig. It is suggested that this locus could be a marker for genetic differences between the domestic and the wild forms of Sus scrofa.     

The sexual function of wallowing in male wild boar (Sus scrofa)

The wild boar (Sus scrofa) is a medium-sized ungulate that produces a large variety of marks. Traditionally, wallowing is an activity that has fundamentally been related to several processes such as thermoregulation, reduction in the number of ectoparasites or disinfection of wounds in the skin of males resulting from fights to reach females. In this study, I analysed another possible function of wallowing in free-ranging wild boar populations when temperatures are low and parasitic numbers are not significant. The results indicate that during the sampling time, from October to February, the number of wild boars with a mud layer on their skin was 47, out of a total of 558 wild boar analysed. Of these 47 wild boars, 44 were males and within this group, 40 individuals were adult males. The wallowed males were bigger and older than non-wallowed males hunted at the same time. In addition, I found that males wallowed mainly during autumn (90.9% of all cases). In the total number of wild boars analysed, I did not notice individuals with wounds resulting from fights other than from the hunting day. On the other hand, the analysis of the females reproductive systems indicated that the rut period took place during the last days of October and the first days of November. From these results, the coincidence of the rut period with the maximum of wallowing in adult males could be indicative of a sexual function of this activity.     

Testis morphometry, duration of spermatogenesis, and spermatogenic efficiency in the wild boar (Sus scrofa scrofa)

The wild boar is a natural inhabitant of Europe, Asia, and North Africa and is phylogenetically the ancestor of the domestic pig. Because of its phylogenetic and economic importance, this species is an interesting model for studying testis function in boars. Therefore, the present study was performed to investigate the testis structure, spermatogenic cycle length, and Sertoli cell (SC) and spermatogenic efficiencies in eight adult wild boars. Each spermatogenic cycle lasted 9.05 days, and the total duration of spermatogenesis was estimated as lasting approximately 41 days. The percentages of testis volume occupied by seminiferous tubules and by Leydig cells were 87% and 6%, respectively. The mean number of SCs per gram of testis was 42 million. The SC (round spermatids per SC) and spermatogenic (daily sperm production per gram of testis) efficiencies were 6.6 cells and 28.6 million, respectively. In general, the testis structure, overall germ cell associations at the different stages of the seminiferous epithelium cycle, and duration of spermatogenesis in the wild boar were similar to those in domestic pigs. Probably because of the small size of Leydig cells (400 microm3), their number per gram of testis (157 million) was the highest among investigated mammalian species. Although the SC efficiency in wild boars was low, their spermatogenic efficiency was comparable to that observed in domestic pigs, mainly because of the higher number of SCs per gram of testis in wild boars. These data suggest that SCs became more efficient during evolution, genetic selection, and domestication in pigs.     

Differences in the activity pattern of the wild boar Sus scrofa related to human disturbance

Over the last century, human activity has caused significant changes to the activity patterns of many wildlife species. The wild boar is one species known to change its activity pattern with the intensity of human disturbance. We conducted camera trap surveys in two study sites, Shingo and Himuro, in Tochigi, central Japan. We investigated effects of two types of human disturbance on the activity pattern of a wild boar population: ‘direct’ disturbance related to hunting activity and ‘indirect’ disturbance related to daily human activity. In the hunting season, relative abundance indices (RAI) of wild boars significantly decreased, and the proportion of activity at night increased compared with the nonhunting season. RAI of wild boars at night decreased with increasing distance from the settlement, while RAI of wild boars during the day did not. Relative proportion of activity at night was higher in cameras at 0–200 m from the settlements, while no significant pattern was found in cameras far from settlements. Both direct and indirect effects of human activity had a significant effect on the activity pattern of wild boars. A decrease in human activity may result in the rapid expansion of wild boar populations, and re-evaluation of the human factor is important for more intelligent management of wild boar populations and to solve the human–wildlife conflict.