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TABLE 1. Genetic variation (mean values) in diploid (2n) and tetraploid (4n) populations (Soltis and Soltis, 1993)

 

P

H

A

Species

2n

4n

2n

4n

2n

4n

Tolmiea menziesii

0.240

0.408

0.070

0.237

3.0

3.53

Heuchera grossulariifolia

0.238

0.311

0.058

0.159

1.35

1.55

Heuchera micrantha

0.240

0.383

0.074

0.151

1.41

1.64

Dactylis glomerata

0.70

0.80

0.17

0.43

1.51

2.36

Turnera ulmifolia

var. elegans

0.459

0.653

0.11

0.42

2.20

2.56

var. intermedia

0.459

0.201

0.11

0.07

2.20

2.00

P, proportion of loci polymorphic; H, observed heterozygosity; A, mean number of alleles per locus.

the diploid parents. We will present both theory on why we might expect increased selfing in polyploids and empirical data for selected ferns and angiosperms.

Theoretical models predict reduced inbreeding depression in polyploids relative to their diploid parents, because of the buffering effect of additional genomes: Deleterious alleles are masked by the extra genomes (Stebbins, 1971; Richards, 1986; Barrett and Shore, 1989). Both allopoly-

TABLE 2. Examples of polysomic inheritance (Soltis and Soltis, 1993)

Species

Inheritance

Evidence

Allium nevii

Tetrasomic

Isozymes

Chrysanthemum morifolium

Hexasomic

Morphology

Dactylis glomerata

Tetrasomic

Isozymes

Dahlia variabilis

Tetrasomic

Morphology

Haplopappus spinulosus

Tetrasomic

Isozymes

Heuchera grossulariifolia

Tetrasomic

Isozymes

Heuchera micrantha

Tetrasomic

Isozymes

Lotus corniculatus

Tetrasomic

Cyanogenic markers, isozymes

Lythrum salicaria

Tetrasomic

Morphology

Maclura pomifera

Tetrasomic

Isozymes

Medicago falcata

Tetrasomic

Morphology, isozymes

Medicago sativa

Tetrasomic

Morphology, isozymes

Pachycereus pringlei

Tetrasomic

Isozymes

Phleum pratense

Hexasomic

Morphology

Solanum tuberosum

Tetrasomic

Morphology, isozymes

Tolmiea menziesii

Tetrasomic

Isozymes

Turnera ulmifolia

var. elegans

Tetrasomic

Isozymes

var. intermedia

Tetrasomic

Morphology, isozymes

Vaccinium corymbosum

Tetrasomic

Isozymes



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