Multiple mating and paternity determinations in domestic swine (Sus scrofa)

Abstract

-When a sow copulates with different boars, fecundation can take a slant towards the best quality male, which should have a more competitive ejaculation. In polyandric animals, genitals can be more elaborated and be an indication of spermatic competence or cryptic female choice. In swine, the male and female genital morphologic characteristics are evidence that allow the assumption of spermatic competence and cryptic choice in this species. In order to prove this hypothesis, the paternity of a group of 18 York/Landrace (Y/N) sows was determined; these sows copulated with three boars: Yorkshire (Y/Y), York/Landrace (Y/N) and Landrace (N/N). The three boars had the same probability of copulating in the first, second, and third place with each of the sows in an interval of 12 hours between each mating. Four polymorphic molecular markers were used in order to establish the paternity (S0033, S0035, S0036 and S0037). The results indicate that the Y/N male had 85.59% of paternity, Y/Y male 8.8% and N/N 5.8%. According to the mating order, when the Y/N male copulated in the first place, it had 89.6% paternity (26 offspring; 12 males; 46.15% and 14 females, 53.85%) when it copulated in the second place, it had 100% paternity (8 offspring; 4 males, 50% and 4 females, 50%), and when it mated in the third place, it had 77.41% paternity (22 offspring; 13 males, 59.1% and 9 females, 40.9%). Sows in estrus participated in the removal of semen from four sows minutes after the copula by female-female mating. The multiple mating allowed certain competence among the ejaculation and the possibility of the female to slant the paternity towards the heterozygote male with higher genetic variability, compared to the homozygote male (Y/Y and N/N). accouplements multiples / choix cryptique de la femelle / microsatellites / porc

Multiple paternity in domestic pigs under equally probable natural matings – a case study in the endangered Gochu Asturcelta pig breed

“…Mate guarding has been reported to play a significant role in sexual selection in wild boar (Delgado et al, 2008). By contrast with previous reports (Aguilera-Reyes et al, 2006), our data were obtained without copulatory restrictions and, particularly in the case of the full sibs forming the analysed group A, no differences in hybrid vigour. Our results clearly show that (a) multiple paternities are possible in domestic pigs under natural mating and (b) when no differences in animal size, development, hybrid vigour or probabilities of mating exist, no differences in paternity success are to be expected.…”

“…Our results can also be useful to further understand the mating system of the wild boar (Costa et al, 2012). There is extensive evidence of multiply sired litters in wild board that are likely to be due to ethological rather than to biological factors (Aguilera-Reyes et al, 2006;Delgado et al, 2008;Poteaux et al, 2009).…”

“…Heterospermic artificial inseminations give litters with multiple paternities in domestic pigs (Berger et al, 1996;Stahlberg et al, 2000). In addition, Aguilera-Reyes et al (2006) have reported multiple paternities in naturally mated sows under a planned mating system with intervals of 12 h between each mating. The experiment by AguileraReyes et al (2006) included a few variables, namely the hybrid vigour of the most successful boar and the interval among subsequent matings that could affect the reported results.…”

Romanian wild boars and Mangalitza pigs have a European ancestry and harbour genetic signatures compatible with past population bottlenecks

“…Natural migratory events as well as intentional wild boar translocation and restocking of forestlands where this species became extinct 27 28 may have counteracted the effects of factors that tend to reduce population size. Indeed, wild boars can travel considerable distances (sometimes >250 km), particularly when males reach sexual maturity or before the beginning of the mating season 20 , and multiple paternities in a single litter may occur 29 30 . The occasional admixture between pigs and wild boars, could have also augmented the diversity of the latter, since the main porcine commercial breeds carry Asian alleles to a significant extent 14 .…”

Socio‐genetic structure and mating system of a wild boar population

“…Rearing of piglets is likely cooperative in this species (Kaminski et al , 2005), making misidentification between offspring and their putative mother a distinct possibility. However, in domestic pigs, it has been observed that sows mate with different males and often produce litters of mixed paternity (Aguilera‐Reyes et al , 2006; Drake, Fraser & Weary, 2008). Multiple paternities were also observed in a large proportion of feral sows from another Australian population (Spencer et al , 2005).…”