Single‐Generation Estimates of Individual Fitness as Proxies for Long‐Term Genetic Contribution

Individual fitness is a central evolutionary concept, but the question of how it should be defined in empirical studies of natural selection remains contentious. Using founding cohorts from long‐term population studies of two species of individually marked birds (collared flycatcherFicedula albicoll...

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Bibliographic Details
Published in:The American naturalist 2004-04, Vol.163 (4), p.505-517
Main Authors: Brommer, Jon E., Gustafsson, Lars, Pietiäinen, Hannu, Merilä, Juha
Format: Article
Language:English
Subjects:
Animals
Birds of prey
Breeding
Comparative analysis
Descendants
Ecological competition
Ecosystem
Female
Female animals
Ficedula albicollis
Flycatchers
Genetics
Health
Male
Models, Biological
Owls
Passeriformes - genetics
Passeriformes - physiology
Population estimates
Population genetics
Population growth rate
Reproduction - genetics
Reproduction - physiology
Selection, Genetic
Strigiformes - genetics
Strigiformes - physiology
Strix uralensis
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Summary:Individual fitness is a central evolutionary concept, but the question of how it should be defined in empirical studies of natural selection remains contentious. Using founding cohorts from long‐term population studies of two species of individually marked birds (collared flycatcherFicedula albicollisand Ural owlStrix uralensis), we compared a rate‐sensitive (λind) and a rate‐insensitive (lifetime reproductive success [LRS]) estimate of individual fitness with an estimate of long‐term genetic fitness. The latter was calculated as the number of gene copies present in the population after more than two generations, as estimated by tracing genetic lineages and accounting for the fact that populations were not completely closed. When counting fledglings, rate‐insensitive estimates of individual fitness correlated better than rate‐sensitive estimates with estimated long‐term genetic contribution. When counting recruits, both classes of estimates performed equally well. The results support the contention that simple, rate‐insensitive measures of fitness, such as LRS, provide a valid and good estimate of fitness in evolutionary studies of natural populations.
ISSN:0003-0147
1537-5323
DOI:10.1086/382547