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The Lanyu pig is an indigenous breed from Lanyu Islet, located south-east of Taiwan, with phenotypic characteristics distinctive from other pig breeds in Asia and Europe. Based on geographic considerations, the Lanyu pig may have originated from mainland China, Austronesia or the Ryukyu Islands. In the present study, polymorphism of the mitochondrial DNA control region sequence was used to clarify phylogenetic relationships among two herds of Lanyu pigs imported before 1980 from Lanyu Islet into Taiwan and reared in isolation on two different farms. Two distinct mitochondrial control region haplotypes were found. The type I Lanyu sequence appeared independently as a unique clade different from Asian and European pig sequences, while the type II Lanyu sequence was clustered within the major Asian clade. The pairwise distances between the major Asian clade vs. the type I Lanyu and European clades were 0.01726 +/- 0.00275 and 0.01975 +/- 0.00212 changes per site respectively. Estimates of divergence time suggest that the type I Lanyu sequence split from the major Asian pig clade in prehistoric times. The type II Lanyu mtDNA shares a close genetic lineage with Japanese Satsuma and New Zealand Kune Kune mtDNA with pairwise distances of 0.00095 +/- 0.00000 and 0.00192 +/- 0.00000 respectively, indicating gene flow between Lanyu Islet, Japan and Oceania in recent times. Together these results indicate that the type I Lanyu pig has a genetic lineage separate from Asian-type pigs, while the type II Lanyu sequence may represent a more recent introgression of modern Asian pigs.

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We investigated infections with Gasterophilus spp. in three equids within the Kalamaili Nature Reserve (northern China). We conducted necropsies on 6 Przewalski’s horses (Equus ferus przewalskii) and 6 Mongolian wild asses (Equus hemionus) and administered ivermectin to 10 overwintering domestic horses to expel parasites during winter periods. All 22 equids studied (100%) were infested with Gasterophilus spp. and a total of 17,225 larvae were collected. These included six species: G. haemorrhoidalis, G. inermis, G. intestinalis, G. nasalis, G. nigricornis, and G. pecorum. The mean intensity of Gasterophilus spp. larvae was 1904 in Przewalski’s horses, 780 in Mongolian wild asses, and 113 in domestic horses. Gasterophilus pecorum was the most abundant species in all three equids. Przewalski’s horses, a reintroduced species, had a significantly higher intensity of Gasterophilus spp. than the Mongolian wild ass, indicating greater susceptibility to parasites in its ancestral home.

The Lanyu pig is an indigenous miniature pig breed on Lanyu Islet near Taiwan, with a mitochondrial DNA genetic lineage remote from Asian and European pig breeds. The unknown population genetic structure and increased inbreeding among the small population of conserved Lanyu pigs is now of great conservation concern. Additionally, the presence for more than a century of exotic pig breeds in Taiwan has made gene introgression from exotic pig breeds into Lanyu pigs very possible. The present study thus aimed to investigate nuclear genetic variation within the conserved Lanyu pigs and the phylogenetic relationship and possible genetic introgression between Lanyu and exotic pig breeds by determining the polymorphism of 19 microsatellite loci. In the neighbor-joining tree constructed from 7 pig breeds based on Cavalli-Sforza and Edward chord genetic distances, 3 major clades were recognized, in which the Asian and European breeds were separately clustered into 2 clades with a 93.0 and 99.9% bootstrap confidence value, respectively. All individuals of the Lanyu breed formed a unique subclade within the Asian clade based on the distance of the proportion of shared alleles, -ln(ps), suggesting that the Lanyu breed possesses a unique nuclear genetic structure and that no nuclear gene introgression from exotic breeds into the conserved Lanyu pigs has occurred in recent history. Fifteen of 19 microsatellite loci deviated from Hardy-Weinberg equilibrium (by Wright's statistic), suggesting a significant loss of heterozygosity in the conserved population. The valuable nuclear genetic structure and phylogenetic information should assist future conservation and population management of Lanyu pigs.