The effects of sibling reproduction in the African striped mouse

Abstract

Neville PILLAY Pillay N. 1999. The effects of sibling reproduction in the African striped mouse. Acta Theriologica 44: 291-298.Sibling reproduction was studied in a captive population of the African striped mouse Rhabdomys pumilio (Sparrman, 1784) to establish the occurrence of inbreeding and whether early association prevents later matings. Sibling and nonsibling pairs were established by pairing animals at weaning (16 days), 30, and 60 days old. The reproductive success of weaning pairs (regardless of genetic relationship) and 30-and 60-day sibling pairs was poorer than that of nonsibling pairs. Inbreeding depression was indicated by high pre-weaning mortality and smaller mass of inbred compared to outbred litters. When pairings were made between sexually mature siblings of consecutive litters that had made brief contact previously, sibling pairs had similar reproductive performance compared to control pairs, but had significantly smaller litter sizes. It appears that incestuous matings in R. pumilio result in inbreeding depression, and that mating between kin or non-kin is prevented by prior association.Environmental Physiological Studies Research (ESPR) Programme,

Cooperative Breeding in Groups of Synchronously Mating Females and Evolution of Large Testes to Avoid Sperm Depletion in African Striped Mice1

“…Furthermore, we did not observe any incidences of aggression between females of either population in any of our experiments. Thus, we have no indication of sexual suppression in striped mouse females, and in fact, promiscuous females synchronized their estrus in our colony [51]. We cannot totally exclude the possibility of sexual suppression, but the most parsimonious explanation of our results is that sperm depletion occurred in the promiscuous but not the polygynous population, leading to significant fitness costs for males and females.…”

“…Polygynous striped mouse males must fertilize several females within 1-2 days of their synchronous estrus [51], leading to synchronized births, as observed in the field [33]. In cooperatively breeding rodents, unsynchronized births yield the risk of infanticide by females that give birth later [52][53][54][55].…”

Fostering in the African striped mouse: implications for kin recognition and dominance

“…The only difference between foster pups before and after 10 days old (ie threshold age for acceptance/rejection) was age and diet. Since captive R. pumilio females were highly tolerant of their offspring beyond the age of weaning (Pillay 1999), diet and not age may be the factor influencing successful fostering.…”

“…Young R. pumilio are weaned at 15-16 days of age (Brooks 1982, Pillay 1999, although young start eating food as early as 10 days old, from which time the incidence of suckling decreases steadily until weaning (Brooks 1982). Thus, the important difference between young fostered before and after 10 days of age is that the latter group were eating solid food.…”

“…Fostered individuals and those individuals raised with foster pups were those derived from experiment 1. These mice were tested when they were 60 days of age and sexually mature (Pillay 1999). All animals were weighed to the nearest 0.1 g immediately before their encounter, and only individuals weighing within 10 g of each other were used.…”