Genetic diversity within provenance and cultivar germplasm collections versus natural populations of pecan (Carya illinoinensis)
1999
Ruter, B. | Hamrick, J.L. | Wood, B.W.
We examined the question of whether the genetic diversity contained within germplasm and cultivar collections of pecan [Carya illinoinensis (Wangenh.) K. Koch] is representative of that found in natural populations of the species. To this end, levels of genetic variation were compared within and among provenance and cultivar collections as well as eight natural populations. Within the species, 13 of 16 (81%) allozyme loci were polymorphic and expected heterozygosity was 0.153. The highest pooled genetic diversity value was found within wild populations (H(e) = 0.167) and the lowest within the provenance collection (H(e) = 0.144). Provenance accessions had lower heterozygosity values in the southern and eastern parts of its range than in the northern portion of its range. Collection methods for provenance and wild population collections captured similar levels of allelic diversity. On average, 94% of the total genetic diversity was found within wild populations and provenance accessions. The number of alleles present in the provenance and wild populations were similar, but several low-frequency alleles were absent from the cultivar collection.
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