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Factors affecting effective population size estimation in a seed orchard: a case study of Pinus sylvestris Du š an Gömöry 1 , Roman Longauer 2 , Ladislav Paule 1 , Rudolf Bruch ánik 3. 1 Department of Phytology, Technical University in Zvolen, Zvolen, Slovakia

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1 department of phytology technical university in zvolen zvolen slovakia

Factors affecting effective

population size estimation

in a seed orchard: a case study

of Pinus sylvestris

Dušan Gömöry1, Roman Longauer2,

Ladislav Paule1, Rudolf Bruchánik3

1Department of Phytology, Technical University in Zvolen, Zvolen, Slovakia

2National Forestry Centre, Forestry Research Institute , Zvolen, Slovakia

3State Forests of the Slovak Republic, General Directorate, Banská Bystrica, Slovakia


1 department of phytology technical university in zvolen zvolen slovakia

Ideal seed orchard:

Randomly mating Mendelian population

Contribution of genotypes to male and

female gamete pools proportionate

to their frequencies

No change of allelic frequencies over

generations


1 department of phytology technical university in zvolen zvolen slovakia

Real clonal seed orchards of European

conifers:

Marker studies:

Generally no or small deviations of genotypic

frequencies from HWE expectations

Low levels of self-fertilization

but (1)

Sometimes significant differences in allelic

frequencies between seed orchard and the

crop

but (2)

Marker studies cannot easily be done everywhere


1 department of phytology technical university in zvolen zvolen slovakia

  • Ideal clonal seed orchard:

  • Equal contribution of parental clones

  • to the gene pool of the seed crop

  • Reality:

  • Deviations from equal contribution because of:

  • unequal female gamete contributions

  • unequal male gamete contributions

  • phenological isolation

  • pollen dispersal in space (distribution of clones –

  • distance-dependent dispersal, wind direction,

  • turbulences)

  • genetic incompatibilities


1 department of phytology technical university in zvolen zvolen slovakia

  • Consequences:

  • loss of genetic diversity in seed orchard crops

  • increased coancestry (potentially higher

  • inbreeding in the following generation)

  • Monitoring the genetic diversity in seed

  • orchard crops:

  • Effective population size (e.g. effective number

  • of clones)

  • Status number (Lindgren et al. 1996:

  • Silvae Genet. 45: 52–59).

  • NS= 0.5/Θ

  • = number of unrelated non-inbred genotypes

  • having the same average coancestry as

  • the considered population



1 department of phytology technical university in zvolen zvolen slovakia

Assessed characteristics (for each ramet):

Female gamete contribution – cone weighting

Male gamete contribution – counting and size

assessment of male strobili

Flowering phenology: 3 dates in Háj and Sýkorová,

5 dates in Kolkáreň, 5 developmental stages for

male strobili, 6 stages for female strobili

Spatial dispersal of pollen: negative exponential

dispersal function (Adams & Birkes 1991)


1 department of phytology technical university in zvolen zvolen slovakia

  • Alien genotypes present in all three seed orchards (rootstocks with aborted scions,

  • unregistered clones, …) as proved by allozyme genotyping

  • Three situations considered:

  • Alien material removed

  • Alien ramets not removed but not

  • harvested

  • (3) Cones harvested from all ramets


1 department of phytology technical university in zvolen zvolen slovakia

Effective number, status number (rootstocks with aborted scions,

and coancestry estimates

F – female contributions assessed, M –male contributions assessed,

P – phenology assessed, D – pollen flow considered


1 department of phytology technical university in zvolen zvolen slovakia

Effective number, status number (rootstocks with aborted scions,

and coancestry estimates Háj


1 department of phytology technical university in zvolen zvolen slovakia

Effective number, status number (rootstocks with aborted scions,

and coancestry estimates

F – female contributions assessed, M –male contributions assessed,

P – phenology assessed, D – pollen flow considered


1 department of phytology technical university in zvolen zvolen slovakia

Effective number, status number (rootstocks with aborted scions,

and coancestry estimates Sýkorová


1 department of phytology technical university in zvolen zvolen slovakia

Effective number, status number (rootstocks with aborted scions,

and coancestry estimates

F – female contributions assessed, M –male contributions assessed,

P – phenology assessed, D – pollen flow considered


1 department of phytology technical university in zvolen zvolen slovakia

Effective number, status number (rootstocks with aborted scions,

and coancestry estimates Kolkáreň


1 department of phytology technical university in zvolen zvolen slovakia

  • Conclusions (rootstocks with aborted scions,

  • In old, fully fructificating seed orchards of Scots pine in Central Europe, effective number of clones is a sufficient estimator of the effective population size

  • Phenology and spatially-dependent pollen dispersal do not considerably affect NS estimates and need not be assessed for practical purposes

  • Young seed orchard are unbalanced and phenologically not synchronized, consequently, effective number of clones is a poor estimator of effective size and status number is affected by all factors (male + female fertility, phenology, spatial design)


1 department of phytology technical university in zvolen zvolen slovakia

Thank you for your attention (rootstocks with aborted scions,