Response of the Eastern Chipmunk, Tamias Striatus, to Sex Ratio Manipulations

Galloway, Martin; Boonstra, Rudy

doi:10.2307/3565865

Cited by 5 publications

(6 citation statements)

References 33 publications

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“…). Males search intensively for oestrous females (Galloway & Boonstra ) even when snow cover is extensive and ambient temperatures are low. As a male's chances to monopolize larger parts of mixed litters are higher in spring than in summer reproduction (Bergeron et al .…”

Section: Discussionmentioning

confidence: 99%

“…Hence, male-male scramble competition is intense, as reflected by mixed paternities of litters (Bergeron et al 2011b). Males search intensively for oestrous females (Galloway & Boonstra 1989) even when snow cover is extensive and ambient temperatures are low. As a male's chances to monopolize larger parts of mixed litters are higher in spring than in summer reproduction (Bergeron et al 2011b), male investment in spring reproduction should have strong effects on its lifetime fitness and sexual selection should thus favour high levels of normothermy in males.…”

Section: H E T E R O T H E R M Y V a R I E S B E T W E E N S E X E Smentioning

confidence: 99%

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Individual variation in energy‐saving heterothermy affects survival and reproductive success

et al. 2016

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Summary Given fundamental energetic trade‐offs among growth, maintenance and reproduction, individual differences in energy saving should have consequences for survival and reproductive success. Many endotherms use periodic heterothermy to reduce energy and water requirements and individual variation in heterothermy should have fitness consequences. However, attempts to disentangle individual‐ and population‐level variation in heterothermy are scarce. Here, we quantified patterns of heterothermy of 55 free‐ranging eastern chipmunks (Tamias striatus), food‐hoarding hibernators. Over five hibernation periods, we obtained a total of 7108 daily individual heterothermy indices (median: 118 per individual). Based on an individual reaction norm approach, we found that the use of heterothermy was repeatable and varied among individuals of the same population under similar environmental conditions. This among‐individual variation had consequences for winter survival and reproductive success. Individuals using less heterothermy at the beginning of the winter had decreased survival in resource‐rich but not in resource‐poor years and higher reproductive success in the subsequent breeding season. These results support the hypothesis that fluctuating selection maintains heterothermic diversity and suggest that individualized ecophysiology can contribute to a more thorough understanding of the evolution of energy‐saving strategies in endotherms. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12797/suppinfo is available for this article.

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Section: Discussionmentioning

confidence: 99%

Section: H E T E R O T H E R M Y V a R I E S B E T W E E N S E X E Smentioning

confidence: 99%

Individual variation in energy‐saving heterothermy affects survival and reproductive success

et al. 2016

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“…Patterns of parentage documented in spring 2007 and in all three summer mating seasons are, to our knowledge, the first to show 100% levels of multiple paternity in mammals. In chipmunks, males search intensively for oestrus females during the reproductive season (Galloway & Boonstra, 1989). Our genetic analyses corroborate previous behavioural observations that many males usually congregate on oestrus females’ home range to mate (Elliott, 1978; Galloway & Boonstra, 1989).…”

Section: Discussionmentioning

confidence: 99%

“…In chipmunks, males search intensively for oestrus females during the reproductive season (Galloway & Boonstra, 1989). Our genetic analyses corroborate previous behavioural observations that many males usually congregate on oestrus females’ home range to mate (Elliott, 1978; Galloway & Boonstra, 1989). Other sciurid rodents such as red squirrels ( Tamiasciurus hudsonicus ) and some ground squirrels (e.g.…”

Section: Discussionmentioning

confidence: 99%

Evidence of multiple paternity and mate selection for inbreeding avoidance in wild eastern chipmunks

Bergeron

Réale

Humphries

et al. 2011

Journal of Evolutionary Biology

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Mate selection for inbreeding avoidance is documented in several taxa. In mammals, most conclusive evidence comes from captive experiments that control for the availability of mates and for the level of genetic relatedness between mating partners. However, the importance of mate selection for inbreeding avoidance as a determinant of siring success in the wild has rarely been addressed. We followed the reproduction of a wild population of eastern chipmunks (Tamias striatus) during five breeding seasons between 2006 and 2009. Using molecular tools and parentage assignment methods, we found that multiple paternity (among polytocous litters) varied from 25% in an early‐spring breeding season when less than a quarter of females in the population were reproductively active to 100% across three summer breeding seasons and one spring breeding season when more than 85% of females were reproductively active. Genetically related parents were common in this population and produced less heterozygous offspring. Furthermore, litters with multiple sires showed a higher average relatedness among partners than litters with only a single sire. In multiply sired litters, however, males that were more closely related to their partners sired fewer offspring. Our results corroborate findings from captive experiments and suggest that selection for inbreeding avoidance can be an important determinant of reproductive success in wild mammals.

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“…Fourthly, dispersal is male‐biased in eastern chipmunks (Loew ; Chambers & Garant ), and thus, we should find a positive relationship between the genetic and the geographic distance between two females, and an absence of relationship or a negative relationship between genetic and geographic distances between two males. Fifthly, resource availability generally affects the distribution of females (Galloway & Boonstra ; Lambin et al . ) and tolerance and space sharing among related females have been reported in other rodent species, particularly at low resource availability (Wolff & Sherman ).…”

Section: Introductionmentioning

confidence: 99%

Environmental conditions affect spatial genetic structures and dispersal patterns in a solitary rodent

et al. 2012

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The study of the spatial distribution of relatives in a population under contrasted environmental conditions provides critical insights into the flexibility of dispersal behaviour and the role of environmental conditions in shaping population relatedness and social structure. Yet few studies have evaluated the effects of fluctuating environmental conditions on relatedness structure of solitary species in the wild. The aim of this study was to determine the impact of interannual variations in environmental conditions on the spatial distribution of relatives [spatial genetic structure (SGS)] and dispersal patterns of a wild population of eastern chipmunks (Tamias striatus), a solitary rodent of North America. Eastern chipmunks depend on the seed of masting trees for reproduction and survival. Here, we combined the analysis of the SGS of adults with direct estimates of juvenile dispersal distance during six contrasted years with different dispersal seasons, population sizes and seed production. We found that environmental conditions influences the dispersal distances of juveniles and that male juveniles dispersed farther than females. The extent of the SGS of adult females varied between years and matched the variation in environmental conditions. In contrast, the SGS of males did not vary between years. We also found a difference in SGS between males and females that was consistent with male-biased dispersal. This study suggests that both the dispersal behaviour and the relatedness structure in a population of a solitary species can be relatively labile and change according to environmental conditions.

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Response of the Eastern Chipmunk, Tamias Striatus, to Sex Ratio Manipulations

Cited by 5 publications

References 33 publications

Individual variation in energy‐saving heterothermy affects survival and reproductive success

Individual variation in energy‐saving heterothermy affects survival and reproductive success

Evidence of multiple paternity and mate selection for inbreeding avoidance in wild eastern chipmunks

Environmental conditions affect spatial genetic structures and dispersal patterns in a solitary rodent

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