Genetic Variation in Helianthus annuus and H. bolanderi

Abstract

Electrophoretic evidence was used to compare levels and distribution of genetic variation in three outcrossing taxa: the non-weedy outcrosser, Helianthus bolanderi ssp. exilis, and two weedy taxa, H. bolanderi ssp. bolanderi and H. annuus. No significant differences in levels of genetic variation were observed among these taxa. However, the distribution of genetic variation within ssp. exilis and the two weedy taxa differed markedly. Most of the genetic variation in ssp. exilis resides within populations, whereas the majority of genetic variation in ssp. bolanderi and H. annuus is distributed among populations. Short population duration, founder events, and genetic drift may be responsible for higher genetic differentiation among populations of ssp. bolanderi and H. annuus. The higher levels of genetic variability within populations of ssp. exilis may be due to the greater stability and longer duration of its populations. © 1988.