Sexual and lifetime selection on body size in a marine fish: the importance of life‐history trade‐offs

Many field measurements of viability and sexual selection on body size indicate that large size is favoured. However, life‐history theory predicts that body size may be optimized and that patterns of selection may often be stabilizing rather than directional. One reason for this discrepancy may be t...

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Bibliographic Details
Published in:Journal of evolutionary biology 2011-08, Vol.24 (8), p.1653-1663
Main Authors: JOHNSON, D. W., HIXON, M. A.
Format: Article
Language:English
Subjects:
adaptation
Age Factors
Animal reproduction
Animals
balancing selection
Body Size
coral reef fish
Coral Reefs
Evolution & development
Female
Fish
fitness
invisible fraction
Life cycles
Longevity
Male
Mating Preference, Animal
mating success
optimal body size
Perciformes - anatomy & histology
Perciformes - genetics
Perciformes - growth & development
Physical growth
Reproduction
Selection, Genetic
Stegastes partitus
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Summary:Many field measurements of viability and sexual selection on body size indicate that large size is favoured. However, life‐history theory predicts that body size may be optimized and that patterns of selection may often be stabilizing rather than directional. One reason for this discrepancy may be that field estimates of selection tend to focus on limited components of fitness and may not fully measure life‐history trade‐offs. We use an 8‐year, demographic field study to examine both sexual selection and lifetime selection on body size of a coral reef fish (the bicolour damselfish, Stegastes partitus). Selection via reproductive success of adults was very strong (standardized selection differential = 1.04). However, this effect was balanced by trade‐offs between large adult size and reduced cumulative survival during the juvenile phase. When we measured lifetime fitness (net reproductive rate), selection was strongly stabilizing and only weakly directional, consistent with predictions from life‐history theory.
ISSN:1010-061X
1420-9101
DOI:10.1111/j.1420-9101.2011.02298.x