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The effects of age and environment on the expression of inbreeding depression in Eucalyptus globulus


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Costa e Silva, J, Hardner, CM, Tilyard, P and Potts, BM 2011 , 'The effects of age and environment on the expression of inbreeding depression in Eucalyptus globulus' , Heredity, vol. 107 , pp. 50-60 , doi: 10.1038/hdy.2010.154.

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Inbreeding adversely affects fitness traits in many plant and
animal species, and the magnitude, stability and genetic
basis of inbreeding depression (ID) will have short- and longterm
evolutionary consequences. The effects of four degrees
of inbreeding (selfing, f¼50%; full- and half-sib matings,
f¼25 and 12.5%; and unrelated outcrosses, f¼0%) on
survival and growth of an island population of Eucalyptus
globulus were studied at two sites for over 14 years. For
selfs, ID in survival increased over time, reaching a maximum
of 49% by age 14 years. However, their inbreeding
depression for stem diameter remained relatively stable with
age, and ranged from 28 to 36% across years and sites. ID for
survival was markedly greater on the more productive site,
possibly due to greater and earlier onset of inter-tree
competition, but was similar on both sites for the diameter of
survivors. The deleterious trait response to increasing inbreeding
coefficients was linear for survival and diameter. Nonsignificant
quadratic effects suggested that epistasis did not
contribute considerably to the observed ID at the population
level. Among- and within-family coefficients of variation for
diameter increased with inbreeding degree, and the variance
among the outcrossed families was significant only on the
more productive site. The performance of self-families for
diameter was highly stable between sites. This suggests that,
for species with mixed mating systems, environmentally stable
inbreeding effects in open-pollinated progenies may tend to
mask the additive genotype-by-environment interaction for
fitness traits and the adaptive response to the environment.

Item Type: Article
Authors/Creators:Costa e Silva, J and Hardner, CM and Tilyard, P and Potts, BM
Keywords: outcrossing; selfing; inbreeding depression; additive and non-additive genetic effects; genotype-by-environment interaction; age trends
Journal or Publication Title: Heredity
DOI / ID Number: 10.1038/hdy.2010.154
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