Genetic diversity within provenance and cultivar germplasm collections versus natural populations of pecan (Carya illinoinensis)

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 spe cies. To this end, levels of genetic variation were compared within and amo ng provenance and cultivar collections as well as eight natural populations . Within the species, 13 of 16 (81%) allozyme loci were polymorphic and exp ected heterozygosity was 0.153, The highest pooled genetic diversity value was found within wild populations (H-e = 0.167) and the lowest within the p rovenance collection (H-e = 0.144), Provenance accessions had lower heteroz ygosity values in the southern and eastern parts of its range than in the n orthern portion of its range. Collection methods for provenance and wild po pulation collections captured similar levels of allelic diversity. On avera ge, 94% of the total genetic diversity was found within wild populations an d provenance accessions. The number of alleles present in the provenance an d wild populations were similar, but several low-frequency alleles were abs ent from the cultivar collection.