Seed Banks, Salmon, and Sleeping Genes: Effective Population Size in Semelparous, Age‐Structured Species with Fluctuating Abundance

• Published in: The American naturalist Vol. 167; no. 1; pp. 118 - 135
• Main Author: Waples, Robin S.
• Format: Journal Article
• Language: English
• Published: United States The University of Chicago Press 01-01-2006; University of Chicago, acting through its Press
• Subjects: Adults; Age structure; Aging; Animal populations; Animal reproduction; Animals; Arithmetic mean; Demography; Genes; Genetic Speciation; Harmonic mean; Modeling; Models, Genetic; Plants; Population size; Reproducibility of Results; Reproduction - physiology; Salmon; Salmon - classification; Salmon - genetics; Salmon - growth & development; Seed banks; Seeds
• ISSN: 0003-0147; 1537-5323
• DOI: 10.1086/498584

Previous studies reached contrasting conclusions regarding how fluctuations in abundance affectN
ein semelparous species with variable age at maturity: thatN
eis determined by the arithmetic meanNamong theTyears within a generation (
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; monocarpic plants with seed banks) or the harmonic mean (
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; Pacific salmon). I show that these conclusions arise from different model assumptions rather than inherent differences between the species. Sequentially applying standard, discrete‐generation formulas for inbreedingN
eto a series of nominal generations accurately predicts the multigenerational rate of increase in inbreeding. Variability in mean realized reproductive success across years (
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) is the most important factor determiningN
eandN
e/N. When abundance is driven by random variation in
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,
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. With random variation inN
t
and constant per capita seed production (C), variation in
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is low and
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; however, ifCvaries among years,N
ecan be closer to
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. Because population regulation affects the genetic contribution of entire cohorts of monocarpic perennials,N
efor these species may be more closely approximated by
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than by
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. With density‐dependent compensation,
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, andN
eis further reduced because relatively few breeders make a disproportionate contribution to the next generation.