The dilemma of female mate selection in the brown bear, a species with sexually selected infanticide

Abstract

Because of differential investment in gametes between sexes, females tend to be the more selective sex. Based on this concept, we investigate mate selection in a large carnivore: the brown bear (Ursus arctos). We hypothesize that, in this species with sexually selected infanticide (SSI), females may be faced with a dilemma: either select a high-quality partner based on phenotypic criteria, as suggested by theories of mate choice, or rather mate with future potentially infanticidal males as a counter-strategy to SSI. We evaluated which male characteristics were important in paternity assignment. Among males available in the vicinity of the females, the largest, most heterozygous and less inbred and also the geographically closest males were more often the fathers of the female's next litter. We suggest that female brown bears may select the closest males as a counter-strategy to infanticide and exercise a post-copulatory cryptic choice, based on physical attributes, such as a large body size, reflecting male genetic quality. However, male-male competition either in the form of fighting before copulation or during the post-copulatory phase, in the form of sperm competition, cannot entirely be ruled out.

Surprising migration and population size dynamics in ancient Iberian brown bears ( Ursus arctos )

“…When available, the radiocarbon ages of each specimen was converted in number of generations assuming a value of 12.5 years as mean generation time, in agreement with what is reported for current populations (41). Otherwise, the age of a specimen was inferred from the excavation context; when such information was missing, the age was assumed as equal to the average of absolute ages of the specimens belonging to the same time period.…”

The effects of primiparity on reproductive performance in the brown bear

“…This included hunter-killed males, accidental deaths, damage-control kills, and radio-collared males (arithmetic center of the 95% MCP home range) suspected to have been killed illegally. A 40-km radius was chosen, because 95% of all fathers of cubs in Scandinavia are within this distance from the mothers (Bellemain et al 2006b). A time lag of 1.5 years was chosen, because Swenson et al (1997) have shown that cub loss was highest 1.5 years after an adult male died.…”

“…A time lag of 1.5 years was chosen, because Swenson et al (1997) have shown that cub loss was highest 1.5 years after an adult male died. We deWned an adult as ¸3 years of age, because the Wrst age of male reproduction is 3 years in both study areas (Bellemain et al 2006b;Zedrosser et al 2007a). The software package Ranges 6 (Anatrack, Wareham, Dorset, UK) was used for calculating home range centers.…”

“…Several factors have been proposed as important for survival of brown bear cubs, including nutritional, social and disturbance factors (McLellan 2005;Miller et al 2003;Swenson et al 1997Swenson et al , 2001a; however, Swenson et al (1997Swenson et al ( , 2001b have suggested that SSI, a social factor, is the major agent of brown bear cub mortality in parts of Scandinavia, where 85% of all cubs disappeared during the mating season (Swenson 2003). Females use behavioral strategies that are interpreted as reducing the possibility of infanticide, such as spatial avoidance of adult males (Ben David et al 2004;Wielgus and Bunnell 1994) or multi-male mating (Bellemain et al 2006b). …”

Internal hydrocephalus combined with pachygyria in a wild-born brown bear cub

“…The male was also the father of the mother of the described cub, and 2 years later, this female successfully raised two cubs fathered by the same male. In brown bears, inbreeding generally is uncommon (Bellemain et al 2006); however, in very small populations, as in Austria, it may occur more often. It remains unknown if inbreeding in brown bears is associated with abnormalities such as the described case.…”