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Heritability, plasticity and canalization of Ural owl egg size in a cyclic environment
Author(s) -
KONTIAINEN P.,
BROMMER J. E.,
KARELL P.,
PIETIÄINEN H.
Publication year - 2008
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/j.1420-9101.2007.01468.x
Subject(s) - biology , vole , heritability , phenotypic plasticity , ecology , zoology , population , population cycle , selection (genetic algorithm) , fecundity , evolutionary biology , predation , demography , artificial intelligence , sociology , computer science
Avian egg size is highly variable on the population level, but is considered inflexible on the individual level. On the basis of 2969 measurements of individual eggs collected during 1981–2005, we analysed heritability, plasticity and selection on egg size in the Ural owl, a long‐lived bird that preys on voles. Vole abundance varied in a 3‐year cycle, creating varying food supply across the cycle’s phases. Ural owl egg size is heritable ( h 2 = 60%). Ural owls lay larger eggs in improved food conditions. On the basis of repeated breeding records of 59 females that bred in all vole cycle phases, we show that intra‐individual adjustment (plasticity) explained 22.4% of the variation in egg size across phases. Egg size was under stabilizing selection. Extremely small and extremely large eggs had reduced hatchability, and individuals who laid either large or small eggs had lower lifetime fledgling production than the ones laying intermediately sized eggs. Our findings illustrate how maternal investment in egg size can both be heritable and highly responsive to variable environmental conditions, and suggest that variation in the investment in egg size across individuals is canalized.