Female polyandry dilutes inbreeding in a solitary fast-living hibernator

Batova, O. N.; Vasilieva, Nina A.; Титов, С. В.; Savinetskaya, L. E.; Tchabovsky, A.V.

doi:10.1007/s00265-021-03086-1

Cited by 8 publications

(7 citation statements)

References 83 publications

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“…The presence of a copulatory plug was proposed to be a sign of intense male competition including sperm competition in a population (Munroe and Koprowski 2011). This phenomenon is consistent with the large number of litters of multiple paternity in S. fulvus (Batova et al 2021) and the mating system in yellow ground squirrels; we have described it as scramble competition polygyny Vasilieva and Tchabovsky 2015).…”

Section: Copulatory Plugssupporting

confidence: 84%

Female hormonal profiles and vaginal cytology in a ground squirrel species with prolonged hibernation

Vasilieva¹,

Tikhonova

Savinetskaya³

et al. 2023

Preprint

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Hibernating mammals have highly ordered annual cycles with strict timing of all processes including reproduction; yet female reproductive physiology is poorly studied in these species. We investigated the estrous cycle in yellow ground squirrels (Spermophilus fulvus), which hibernate up to 9 months. On the basis of vaginal cytology and serum progesterone and estradiol profiles, we identified proestrus, estrus, metestrus, and anestrus in the cycle. Similarly to other rodents, predominance of cornified cells marked estrus, and an increase in the leukocyte number reflected metestrus. Estrus started and then pregnancy occurred mostly within 3 days after the spring emergence. In one female, we noticed a copulatory plug for the first time for this species. The progesterone level increased from proestrus/estrus to pregnancy and decreased in the postlactation period. Estradiol concentration did not change significantly throughout the estrous cycle but varied among females and was consistently high in some of them. The hormone levels did not vary with female age despite smaller body size in yearling females as compared with older ones. We did not find any evidence for the second estrus. During postlactation, progesterone concentration diminished toward hibernation, and we failed to detect signs of prehibernation activation of the female reproductive system. Probably, gonadal preparation in S. fulvusfemales proceeds at periodic arousals during hibernation. Our data showed fast transitions between phases of the female estrous cycle and early maturation of juvenile females, thus supporting the hypothesis of fast life history strategy of S. fulvus.

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Section: Copulatory Plugssupporting

confidence: 84%

Female hormonal profiles and vaginal cytology in a ground squirrel species with prolonged hibernation

Vasilieva¹,

Tikhonova

Savinetskaya³

et al. 2023

Preprint

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“…In these and some other ground squirrel species, young females survived better than males ( Michener, 1989 ), which is often attributed to male-biased dispersal and male risky behavior. Dispersal is male biased in yellow ground squirrels ( Batova et al 2021 ). In addition, although they are of similar body mass at weaning, males grow faster than females ( Vasilieva et al 2009 ; Vasilieva and Tchabovsky 2018 ).…”

Section: Discussionmentioning

confidence: 99%

“…Large-sized adult yellow ground squirrels very seldom suffer predation. Females are philopatric and form spatial kin clusters ( Batova et al 2021 ); however, they use separate burrows and only have partially overlapping home ranges. Young males typically leave the natal site and disperse within the colony.…”

Section: Methodsmentioning

confidence: 99%

“…This is a typical colony of yellow ground squirrels in southern Russia ( Shilova et al 2015 ). The high proportion of closely related males and females within the colony suggested that the dispersal beyond the colony was rare ( Batova et al 2021 ). We have permanently marked squirrels in the colony since 2001; therefore, we knew the origin and the fates of almost all litters in the study area.…”

Section: Methodsmentioning

confidence: 99%

“…We suggested that the sex of juveniles would modulate the survival curves because males are dispersing sex while females are philopatric ( Batova et al 2021 ). Thus, we expected the survival curves of males and females to diverge from the 14th day after the emergence and later due to higher mortality in males.…”

Section: Methodsmentioning

confidence: 99%

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Juvenile survival curves in a solitary ground squirrel with a prolonged hibernation: effects of individual characteristics, environment, and maternal investment

2022

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Juvenile survival is a key life-history influence on population dynamics and adaptive evolution. We analyzed the effects of individual characteristics, early environment, and maternal investment on juvenile survival in a large solitary hibernating rodent – yellow ground squirrel Spermophilus fulvus using Cox mixed-effects models. Only 48% of weaned pups survived to dispersal and 17% survived to hibernation. Early life expectancy was primarily determined by individual characteristics and to a lesser extent by the early environment. The strongest and positive predictor of juvenile survival was body mass which crucially affected mortality immediately after weaning. Males suffered higher mortality than females after the onset of dispersal; however, the overall difference between sexes was partly masked by high rates of mortality in the first days after emergence in both sexes. Later-emerged juveniles had lower life expectancy than the earliest pups. The overall effect of local juvenile density was positive. Prolonged lactation did not enhance juvenile survival: pups nursed longer survived shorter than the young nursed for a shorter period. Our findings support the hypothesis that females of S. fulvus cannot effectively regulate maternal expenditures to mitigate effects of unfavorable conditions on their offspring. The strategy to deal with seasonal time constraints on life history in female S. fulvus suggests an early termination of maternal care at the cost of juvenile quality and survival. This female reproductive strategy corresponds to a “fast-solitary” life of folivorous desert-dwelling S. fulvus and other solitary ground squirrels with prolonged hibernation.

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Female hormonal profiles and vaginal cytology in a ground squirrel species with prolonged hibernation

Vasilieva,

Tikhonova,

Savinetskaya

et al. 2023

Mamm Biol

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Female polyandry dilutes inbreeding in a solitary fast-living hibernator

Cited by 8 publications

References 83 publications

Female hormonal profiles and vaginal cytology in a ground squirrel species with prolonged hibernation

Female hormonal profiles and vaginal cytology in a ground squirrel species with prolonged hibernation

Juvenile survival curves in a solitary ground squirrel with a prolonged hibernation: effects of individual characteristics, environment, and maternal investment

Female hormonal profiles and vaginal cytology in a ground squirrel species with prolonged hibernation

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