Shi, Xiujie , Michaels, Helen , Mitchell, Randy .
The effects of population size and density on genetic variation and mating system in Lupinus perennis.
Understanding the impacts of changes of population size and density on genetic variation and mating systems is critical to the evaluation of the effect of anthropogenic changes on reproduction in threatened plant populations. We surveyed genetic variation in five paired large and small populations of the threatened species Lupinus perennis using 6 microsatellite loci. Although population size had no significant effect on levels of heterozygosity for adult plants, large populations harbored significantly more alleles than small populations. We further characterized the mating system of 8 populations varying in size and density, using data from 5 polymorphic microsatellite loci. Progeny arrays of 11 open-pollinated offspring from 15-20 maternal plants per population were used to estimate mating system parameters under the mixed mating model. Multilocus outcrossing rates (tm = 0.72 to 0.95) indicated that L. perennis is predominately outcrossing. Outcrossing rate varied among populations, with large populations having significantly higher outcrossing rates than small populations. Furthermore, low-density populations showed a trend toward higher outcrossing rates. Given that all populations show considerable inbreeding depression regardless of size, these results help explain why previous studies have shown that small populations have lower seed production and higher abortion rates.
1 - University of Akron, Biology Department, Akron, Ohio, 443225-3908, USA
2 - Bowling Green State University, Biological Sciences, Life Science Building, Bowling Green, Ohio, 43403, USA
Presentation Type: Paper
Location: Peruvian (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 9:00 AM