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Genetic Confirmation of the Origin of Clarkia lingulata

L. D. Gottlieb
Evolution
Vol. 28, No. 2 (Jun., 1974), pp. 244-250
DOI: 10.2307/2407325
Stable URL: http://www.jstor.org/stable/2407325
Page Count: 7
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Genetic Confirmation of the Origin of Clarkia lingulata
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Abstract

Analysis of electrophoretic variation specified by eight gene loci of Clarkia lingulata and C. biloba revealed a high degree of genetic similarity between them. Using the statistic of Nei, their genetic identity is .88. This finding is concordant with morphological, cytogenetical and geographical evidence that suggests that C. lingulata originated recently in a rapid series of events from a geographically peripheral population of C. biloba (Lewis and Roberts, 1956; Lewis, 1962). Five of the eight genes are polymorphic in both species and also in a single population of the closely related C. dudleyana. But, C. lingulata has fewer alleles than C. biloba. The mean observed proportion of the genome that is heterozygous is about 15% in individuals of C. biloba and 8% in C. lingulata. Significant differences between observed and expected proportion of heterozygous individuals (assuming Hardy-Weinberg equilibrium) in C. lingulata probably reflects inbreeding in this species. Although the two known populations of C. lingulata occupy similar sites only two miles apart in the same canyon, their genetic differences suggest little gene flow between them. Only two new alleles, both at the same locus, appear to have been established in C. lingulata since its origin. The high genetic similarity between the two species in conjunction with evidence previously obtained regarding their relative adaptedness upholds suggestions that speciation in annual plants may be a chance event.

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