No genetic substructuring in Artemisia subgenus Tridentatae despite strong ecotypic subspecies selection

Stanton, D.J.; McArthur, E.D.; Freeman, D.C.; Golenberg, E.M.

No genetic substructuring in Artemisia subgenus Tridentatae despite strong ecotypic subspecies selection

2002

Stanton, D.J. | McArthur, E.D. | Freeman, D.C. | Golenberg, E.M.

Phylogenetic relationships within the subgenus Tridentatae of Artemisia (Asteraceae) were investigated using nuclear ITS and plastid intronic and intergenic sequences in the region of trnL Although the studied taxa are quite distinct morphologically and ecologically, extremely low levels of genetic divergence (average nucleotide differences among haplotypes is pi= 0.0040 and pi = 0.0019, for ITS and trnL, respectively) were observed. Haplotype networks indicate the common haplotypes are widely distributed both geographically and taxonomically and are marked by a high connectivity to other haplotypes. These patterns are consistent with older alleles distributed in populations. These results imply that differentiation within the Tridentatae is the result of strong ecotypic selection over a background of widespread hybridization.

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