Previous Experience and Reproductive Investment of Female Columbian Ground Squirrels

Broussard, David; Dobson, F. Stephen; Murie, Jan O.

doi:10.1644/06-mamm-a-357.1

Cited by 34 publications

(37 citation statements)

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“…The active season is short, because families start to prepare for the 8-9-month period of hibernation soon after young are weaned in early summer (Dobson et al 1999). Mean litter size increases from 2.6 offspring among primiparous yearlings to 3.0 offspring among experienced females (Broussard et al 2008). Columbian ground squirrels are quite long lived for such a small mammal (Dobson and Oli 2001).…”

Section: Dnmentioning

confidence: 99%

How Life History Influences Population Dynamics in Fluctuating Environments

Sæther

Coulson

Grøtan

et al. 2013

The American Naturalist

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174

186

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A major question in ecology is how age-specific variation in demographic parameters influences population dynamics. Based on long-term studies of growing populations of birds and mammals, we analyze population dynamics by using fluctuations in the total reproductive value of the population. This enables us to account for random fluctuations in age distribution. The influence of demographic and environmental stochasticity on the population dynamics of a species decreased with generation time. Variation in age-specific contributions to total reproductive value and to stochastic components of population dynamics was correlated with the position of the species along the slow-fast continuum of life-history variation. Younger age classes relative to the generation time accounted for larger contributions to the total reproductive value and to demographic stochasticity in "slow" than in "fast" species, in which many age classes contributed more equally. In contrast, fluctuations in population growth rate attributable to stochastic environmental variation involved a larger proportion of all age classes independent of life history. Thus, changes in population growth rates can be surprisingly well explained by basic species-specific life-history characteristics. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. Submitted December 17, 2012; Accepted June 19, 2013; Electronically published October 25, 2013 abstract: A major question in ecology is how age-specific variation in demographic parameters influences population dynamics. Based on long-term studies of growing populations of birds and mammals, we analyze population dynamics by using fluctuations in the total reproductive value of the population. This enables us to account for random fluctuations in age distribution. The influence of demographic and environmental stochasticity on the population dynamics of a species decreased with generation time. Variation in age-specific contributions to total reproductive value and to stochastic components of population dynamics was correlated with the position of the species along the slow-fast continuum of life-history variation. Younger age classes relative to the generation time accounted for larger contributions to the total reproductive value and to demographic stochasticity in "slow" than in "fast" species, in which many age classes contributed more equally. In contrast, fluctuations in population growth rate attributable to stochastic environmental variation involved a larger proportion of all age classes independent of * Corresponding author; e-mail: bernt.erik.sather@bio.ntnu.no.Am. Nat. 2013. Vol. 182, pp. 743-759. ᭧ 2013 by The University of Chicago. 0003-0147/2013/18206-54347$15.00. All rights reserved. DOI: 10.1086/67349...

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Section: Dnmentioning

confidence: 99%

How Life History Influences Population Dynamics in Fluctuating Environments

Sæther

Coulson

Grøtan

et al. 2013

The American Naturalist

Self Cite

174

186

View full text Add to dashboard Cite

show abstract

“…Yet, this is not likely for our population as females giving birth around the mean litter birthdate would have been in peak lactation in mid-June and crude protein and digestibility of grasses and forbs on meadows in the Sheep River Provincial Park decline from about early June to mid-August (Bennett, 1999). Alternatively, adult females that reproduce earlier may restrain investment in high fat, energy dense milk as young may have adequate time to compensate post-weaning whereas females breeding later in the season may face constraints associated with the necessity to gain mass in preparation for hibernation (sensu Broussard et al, 2008). In Iberian red deer, hinds that were hormonally manipulated to calve earlier ("advanced hinds") in the season produced milk with lower fat concentration and a higher milk protein:fat ratio relative to hinds with standard calving dates (Gomez et al, 2002).…”

Section: Maternal Characteristics and Milk Compositionmentioning

confidence: 99%

Milk matters: offspring survival in Columbian ground squirrels is affected by nutrient composition of mother's milk

Skibiel

Hood

2015

Front. Ecol. Evol.

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Through maternal effects, information about environmental conditions experienced in the maternal generation can be transmitted to subsequent generations. Although maternal effects have been described and quantified in many mammalian species, the underlying causal links are often under-studied. The close association between mother and neonate during the extended period of lactation in mammals provides a unique opportunity for mothers to influence offspring phenotype through nutrient provisioning of milk. The purpose of this study was to examine sources of inter-individual variation in milk composition and impacts on offspring phenotype and survival. Variation in fat content, protein content, and energy density of mother's milk was associated with timing of reproduction. Mothers with intermediate birthdates produced milk that was higher in fat and energy density, but lower in protein than females with early or late birthdates. In turn, the pattern of change in milk composition affected juvenile overwinter survival. The protein content of Columbian ground squirrel milk typically increases to peak lactation and then declines before weaning. Pups consuming milk that was lower in protein in early lactation but then relatively high in protein at peak and late lactation had a higher probability of survival overwinter. Our results indicate that the interplay between the timing of reproduction and lactation performance has consequences for maternal and offspring fitness.

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“…We will respect this tradition, reserving the term ‘reproductive success’ for the interesting parameter from an evolutionary point of view, namely the product of the probability of breeding by the breeding success of breeders. Despite being an important component of fitness for long-lived vertebrates, and one which has long retained the attention of ecologists [3], breeding probability [1], [4], synonymously breeding propensity [5], is much less studied than breeding success, e.g., [6]–[11]. Indeed, estimating breeding probabilities requires long-term studies of marked individuals [1] and an appropriate statistical framework (capture-recapture models, e.g., [12], [13].…”

Section: Introductionmentioning

confidence: 99%

Breeding Experience Might Be a Major Determinant of Breeding Probability in Long-Lived Species: The Case of the Greater Flamingo

2012

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The probability of breeding is known to increase with age early in life in many long-lived species. This increase may be due to experience accumulated through past breeding attempts. Recent methodological advances allowing accounting for unobserved breeding episodes, we analyzed the encounter histories of 14716 greater flamingos over 25 years to get a detailed picture of the interactions of age and experience. Survival did not improve with experience, seemingly ruling out the selection hypothesis. Breeding probability varied within three levels of experience : no breeding experience, 1 experience, 2+ experiences. We fitted models with and without among-individual differences in breeding probabilities by including or not an additive individual random effect. Including the individual random effect improved the model fit less than including experience but the best model retained both. However, because modeling individual heterogeneity by means of an additive static individual random effect is currently criticized and may not be appropriate, we discuss the results with and without random effect. Without random effect, breeding probability of inexperienced birds was always times lower than that of same age experienced birds, and breeding probability increased more with one additional experience than with one additional year of age. With random effects, the advantage of experience was unequivocal only after age 9 while in young having experience was penalizing. Another pattern, that breeding probability of birds with experiences dropped after some age (8 without random effect; up to 11 with it), may point to differences in the timing of reproductive senescence or to the existence of a sensitive period for acquiring behavioral skills. Overall, the role of experience appears strong in this long-lived species. We argue that overlooking the role of experience may hamper detection of trade-offs and assessment of individual heterogeneity. However, manipulative experiments are desirable to confirm our finding.

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Previous Experience and Reproductive Investment of Female Columbian Ground Squirrels

Cited by 34 publications

References 54 publications

How Life History Influences Population Dynamics in Fluctuating Environments

How Life History Influences Population Dynamics in Fluctuating Environments

Milk matters: offspring survival in Columbian ground squirrels is affected by nutrient composition of mother's milk

Breeding Experience Might Be a Major Determinant of Breeding Probability in Long-Lived Species: The Case of the Greater Flamingo

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