Evidence from Sequence-Tagged-Site Markers of a Recent Progenitor-Derivative Species Pair in Conifers

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 97; no. 21; pp. 11331 - 11336
• Main Authors: Perron, Martin, Perry, Daniel J., Andalo, Christophe, Bousquet, Jean
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 10.10.2000; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: Alleles; Allopatric species; Biodiversity; Biological Sciences; Biological taxonomies; Botany; Conifers; Evolution; Evolutionary genetics; Genetic diversity; Genetic loci; Genetic Markers; Genetic Variation; Heterozygote; Hybridization, Genetic; mentationBioreactorsTemper; ODATA; Population genetics; Population size; Sequence Tagged Sites; Taxa; Trees; Trees - genetics
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.200417097

Black spruce (Picea mariana [B.S.P.] Mill.) and red spruce (Picea rubens Sarg.) are two conifer species known to hybridize naturally in northeastern North America. We hypothesized that there is a progenitor-derivative relationship between these two taxa and conducted a genetic investigation by using sequence-tagged-site markers of expressed genes. Based on the 26 sequence-tagged-site loci assayed in this study, the unbiased genetic identity between the two taxa was quite high with a value of 0.920. The mean number of polymorphic loci, the mean number of alleles per polymorphic locus, and the average observed heterozygosity were lower in red spruce (P = 35%, AP= 2.1, Ho= 0.069) than in black spruce (P = 54%, AP= 2.9, Ho= 0.103). No unique alleles were found in red spruce, and the observed patterns of allele distribution indicated that the genetic diversity of red spruce was essentially a subset of that found in black spruce. When considered in combination with ecological evidence and simulation results, these observations clearly support the existence of a progenitor-derivative relationship and suggest that the reduced level of genetic diversity in red spruce may result from allopatric speciation through glaciation-induced isolation of a preexisting black spruce population during the Pleistocene era. Our observations signal a need for a through reexamination of several conifer species complexes in which natural hybridization is known to occur.