Abstract
Behavioural observations of reproduction and mate choice in wild fossorial rodents are extremely limited and consequently indirect methods are typically used to infer mating strategies. We use a combination of morphological, reproductive, spatial, and genetic data to investigate the reproductive strategy of a solitary endemic species, the Cape dune mole-rat Bathyergus suillus. These data provide the first account on the population dynamics of this species. Marked sexual dimorphism was apparent with males being both significantly larger and heavier than females. Of all females sampled 36% had previously reproduced and 12% were pregnant at the time of capture. Post-partum sex ratio was found to be significantly skewed in favour of females. The paternity of fifteen litters (n = 37) was calculated, with sires assigned to progeny using both categorical and full probability methods, and including a distance function. The maximum distance between progeny and a putative sire was determined as 2149 m with males moving between sub-populations. We suggest that above-ground movement should not be ignored in the consideration of mate acquisition behaviour of subterranean mammals. Estimated levels of multiple paternity were shown to be potentially as high as 26%, as determined using sibship and sire assignment methods. Such high levels of multiple paternity have not been found in other solitary mole-rat species. The data therefore suggest polyandry with no evidence as yet for polygyny.
Highlights
Mammals display a wide range and flexibility of behavioural and social interactions (e.g. [1]), which is well exemplified in their breeding systems
Genotyping Deviations from Hardy-Weinberg Equilibrium and estimates of null alleles are shown in Appendix S1
Genetic analyses have provided evidence for multiple paternity in a fossorial, solitary rodent with males appearing to travel considerable distances to acquire mates. This mirrors the findings in another solitary rodent, Heliophobius argenteocinereus [8]
Summary
Mammals display a wide range and flexibility of behavioural and social interactions (e.g. [1]), which is well exemplified in their breeding systems. The most common mammalian mating system is polygyny [2,3] where male mate acquisition ranges from opportunistic approaches [4], to the competitive attainment of a social or spatial position that confers improved access to females In some species spatial proximity to potential mates reduces aggression and facilitates mating opportunities [6,7]. Attenuated aggression through proximity may be important for subterranean species which experience high energetic costs associated with extending burrow systems in order to locate potential mates.These energetic restrictions may be relaxed by the adoption of alternate strategies such as surface movement [8] or the use of adjoining burrow systems. Males commonly attempt to monopolise females to improve reproductive success, they seldom successfully exclude all competing suitors [9]. Solitary multiparous mammalian species that do not form pair-bonds may be expected to have high levels of multiple paternity (e.g. [10])
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