Oecologia2020; 193(1); 77-87; doi: 10.1007/s00442-020-04649-1

Early predictors of female lifetime reproductive success in a solitary hibernator: evidence for “silver spoon” effect.

Abstract: Fitness consequences of early-life conditions remain unclear and poorly studied in mammals. Based on long-term observations of yellow ground squirrels (Spermophilus fulvus), we identified early determinants of female fitness by analyzing the effects of early-life individual and environmental characteristics (weaning weight, weight gain rate, date of natal emergence, natal litter size, location of the natal burrow, local density of juveniles, population density and precipitation in the post-weaning period) on lifetime reproductive success (LRS). We found high variation and right-skewed distribution in all five LRS components (survival to adulthood, adult lifespan, and lifetime numbers of weaned litters, weanlings, and yearling offspring). Numbers of litters, weanlings, and adult offspring were correlated with each other and increased with lifespan, confirming that longevity is a better predictor of LRS than fecundity. Survival to adulthood was the most sensitive fitness component to early conditions and was higher in females (a) with greater weaning weight, (b) born further from human settlement and (c) born at lower population density. Population density at birth was the best early predictor of all LRS components and negatively influenced adult lifespan and numbers of weanlings and yearling offspring. Early growth rate positively affected the probability of reproducing after the first hibernation and the number of offspring weaned. Such syndrome of high-quality (heavy and fast-growing) young born in a favourable environment ("a silver spoon effect") with downstream damping fitness consequences has been observed so far in only a few mammalian species.
Publication Date: 2020-04-21 PubMed ID: 32318852DOI: 10.1007/s00442-020-04649-1Google Scholar: Lookup
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  • Journal Article

Summary

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The research study focuses on the factors in the early life of female yellow ground squirrels that can predict how successful they will be at reproducing during their lifetime. The scientists found that the weight of the squirrels when they stopped nursing and their rate of weight gain as well as the density of their population, among other factors, all had an impact on their eventual ability to reproduce.

Study Overview

  • The research involved long-term observation of yellow ground squirrels (Spermophilus fulvus) to assess what early-life characteristics could determine female reproductive success.
  • The early-life traits examined included weaning weight, weight gain rate, date of emergence from the natal burrow, and environmental factors such as litter size, juvenile population density, and post-weaning precipitation.

Key Findings

  • A significant variation was noted across all five components of lifetime reproductive success or LRS (survival to adulthood, adult lifespan, and lifetime numbers of weaned litters, weanlings, and yearling offspring).
  • The number of offspring was correlated with each other and increased with lifespan, highlighting the importance of longevity over fecundity (the ability to produce an abundance of offspring) as a predictor of LRS.

Impact of Early-Life Conditions on Survival

  • The study revealed that survival to adulthood was most affected by early-life conditions. Squirrels with greater weaning weight, those born farther from human settlements, and those born in lower population densities had higher survival rates.
  • Population density at birth especially stood out as a reliable predictor of all LRS components and was found to negatively impact adult lifespan and the number of offspring.

“Silver Spoon” Effect

  • The “silver spoon” effect refers to the phenomenon where squirrels born under favorable conditions (having higher weights and experiencing fast growth) were observed to have better reproductive outcomes.
  • The early growth rate of squirrels positively affected the chances of reproduction after their first hibernation cycle and the number of weaned offspring.
  • This early-life advantage leading to better fitness outcomes in adulthood, however, has only been observed in a few mammalian species.

Cite This Article

APA
Vasilieva NA, Tchabovsky AV. (2020). Early predictors of female lifetime reproductive success in a solitary hibernator: evidence for “silver spoon” effect. Oecologia, 193(1), 77-87. https://doi.org/10.1007/s00442-020-04649-1

Publication

ISSN: 1432-1939
NlmUniqueID: 0150372
Country: Germany
Language: English
Volume: 193
Issue: 1
Pages: 77-87

Researcher Affiliations

Vasilieva, Nina A
  • A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 33, Leninskii pr., Moscow, 119071, Russia. ninavasilieva@gmail.com.
Tchabovsky, Andrey V
  • A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 33, Leninskii pr., Moscow, 119071, Russia.

MeSH Terms

  • Animals
  • Female
  • Fertility
  • Horses
  • Longevity
  • Pregnancy
  • Reproduction
  • Sciuridae
  • Silver

Grant Funding

  • 16-04-01376 / u0420u043eu0441u0441u0438u0439u0441u043au0438u0439 u0424u043eu043du0434 u0424u0443u043du0434u0430u043cu0435u043du0442u0430u043bu044cu043du044bu0445 u0418u0441u0441u043bu0435u0434u043eu0432u0430u043du0438u0439 (u0420u0424u0424u0418)

Citations

This article has been cited 2 times.
  1. Poli C, Robertson EP, Martin J, Powell AN, Fletcher RJ Jr. An invasive prey provides long-lasting silver spoon effects for an endangered predator.. Proc Biol Sci 2022 Jun 29;289(1977):20220820.
    doi: 10.1098/rspb.2022.0820pubmed: 35730154google scholar: lookup
  2. Van Allen B, Jones N, Gilbert B, Carscadden K, Germain R. Maternal effects and the outcome of interspecific competition.. Ecol Evol 2021 Jun;11(12):7544-7556.
    doi: 10.1002/ece3.7586pubmed: 34188833google scholar: lookup