Effects of inbreeding on population mean performance and observational variances in Eucalyptus globulus

Silva, João Costa e; Hardner, Craig; Tilyard, Paul; Pires, Ana M.; Potts, Brad M.

doi:10.1051/forest/2010018

Cited by 32 publications

(30 citation statements)

References 34 publications

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“…At 10 years of age, the ID SELF for SURV in the present study was 36% (Table 1) but 74% in the adjacent trial (Costa e Silva et al, 2010a). This marked difference in magnitude of ID SELF occurred despite the field design employed in the present study maximizing competition among cross types, whereas the opposite was done in the adjacent trial by blocking progeny according to cross type.…”

Section: Discussioncontrasting

confidence: 53%

“…It is mainly pollinated by birds and insects, and has a mixed mating system with average outcrossing rates in undisturbed native forests 485% (Mimura et al, 2009). Progeny derived from self-fertilization exhibit severe ID for growth and survival (Hardner and Potts, 1995;Hardner et al, 1998;Costa e Silva et al, 2010a), and there is also evidence for ID following biparental inbreeding in the wild (Hardner et al, 1998).…”

Section: Methodsmentioning

confidence: 99%

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

Silva¹,

Hardner

Tilyard

et al. 2011

Heredity

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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, f ¼ 50%; full-and half-sib matings, f ¼ 25 and 12.5%; and unrelated outcrosses, f ¼ 0%) 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.

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Section: Discussioncontrasting

confidence: 53%

Section: Methodsmentioning

confidence: 99%

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

Silva¹,

Hardner

Tilyard

et al. 2011

Heredity

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“…SELF had 27 and 26 seed parents in common with OP and POL, respectively, and there were 48 parents in common between OP and POL. Details about the plant material, crossing design and trial layout used in this study have been described previously (Costa e Silva et al, 2010).…”

Section: Methodsmentioning

confidence: 99%

“…A linear mixed model incorporating heterogeneity of (co)variances among (fixed) cross types for (random) family and residual effects was fitted to a data vector containing individual tree measures of breast-height diameter (DBH) at ages 4, 6 or 10 years from planting (Costa e Silva et al, 2010). Restricted maximum likelihood (REML) estimates of (co)variance components were obtained by using the average information REML algorithm, implemented in the ASReml software (Gilmour et al, 2006).…”

Section: Methodsmentioning

confidence: 99%

Genetic variation and parental performance under inbreeding for growth in Eucalyptus globulus

Silva¹,

Hardner

Potts

2010

Ann. For. Sci.

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Abstract• We aimed to better understand the genetic architecture of growth in E. globulus undergoing inbreeding by comparing families from selfing (SELF), open pollination (OP) and unrelated polymix crossing (POL) of common parents. Stem diameter at breast height (DBH) was assessed at 4, 6 and 10 years after planting in a field trial.• The OP heritability was overestimated at an early age relative to the POL heritability.• No significant correlations were found between the SELF and POL parental effects, indicating substantial non-additive genetic variation under inbreeding. The OP family effects were better correlated with the SELF than the POL population, and only at age 10 years, after substantial mortality of inbred progeny has occurred, was the positive correlation between OP and POL families significantly different from zero.• The estimated dominance variance arising from inbreeding was nearly 10-fold greater than the dominance variance associated with random mating and the additive variance, and appeared to be a major contributor to the variation in inbreeding depression amongst selfed families.

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“…If this was the case, the adult cohort is likely to have undergone selection against inbred individuals, increasing their mean observed heterozygosity. Because of the long-lived nature of this species (10 s to 100 s of years) and the episodic highstress environment caused by, for example, water availability, extreme temperatures and disease (Parsons, 1969;Keane et al, 2000;Fox and Reed, 2010), there have likely been many opportunities within the lifespan of the standing adults for inbred adults to be selected out of the population (Costa e Silva et al, 2010).…”

Section: Resistance To Fragmentationmentioning

confidence: 99%

Mating system and early viability resistance to habitat fragmentation in a bird-pollinated eucalypt

et al. 2012

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Habitat fragmentation has been shown to disrupt ecosystem processes such as plant-pollinator mutualisms. Consequently, mating patterns in remnant tree populations are expected to shift towards increased inbreeding and reduced pollen diversity, with fitness consequences for future generations. However, mating patterns and phenotypic assessments of open-pollinated progeny have rarely been combined in a single study. Here, we collected seeds from 37 Eucalyptus incrassata trees from contrasting stand densities following recent clearance in a single South Australian population (intact woodland ¼ 12.6 trees ha À1 ; isolated pasture ¼ 1.7 trees ha À1 ; population area ¼ 10 km 2 ). 649 progeny from these trees were genotyped at eight microsatellite loci. We estimated genetic diversity, spatial genetic structure, indirect contemporary pollen flow and mating patterns for adults older than the clearance events and open-pollinated progeny sired post-clearance. A proxy of early stage progeny viability was assessed in a common garden experiment. Density had no impact on mating patterns, adult and progeny genetic diversity or progeny growth, but was associated with increased mean pollen dispersal. Weak spatial genetic structure among adults suggests high historical gene flow. We observed preliminary evidence for inbreeding depression related to stress caused by fungal infection, but which was not associated with density. Higher observed heterozygosities in adults compared with progeny may relate to weak selection on progeny and lifetime-accumulated mortality of inbred adults. E. incrassata appears to be resistant to the negative mating pattern and fitness changes expected within fragmented landscapes. This pattern is likely explained by strong outcrossing and regular long-distance pollen flow.

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Effects of inbreeding on population mean performance and observational variances in Eucalyptus globulus

Cited by 32 publications

References 34 publications

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

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

Genetic variation and parental performance under inbreeding for growth in Eucalyptus globulus

Mating system and early viability resistance to habitat fragmentation in a bird-pollinated eucalypt

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