Skip to main content
ARS Home » Southeast Area » Miami, Florida » Subtropical Horticulture Research » Research » Publications at this Location » Publication #209725
Title: Genetic structure and gene flow among South Florida populations of Iris hexagona Walt. (Iridaceae) assessed with 19 microsatellite DNA loci

Author
item Meerow, Alan
item GIDEON, MICHAEL - GIDEON'S IRIS
item Kuhn, David
item MOTAMAYOR, JUAN-CARLOS - MASTERFOODS (MARS, INC)
item Nakamura, Kyoko

Submitted to: International Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2007
Publication Date: 11/16/2007
Citation: Meerow, A.W., Gideon, M., Kuhn, D.N., Motamayor, J., Nakamura, K. 2007. Genetic structure and gene flow among South Florida populations of Iris hexagona Walt. (Iridaceae) assessed with 19 microsatellite DNA loci. International Journal of Plant Science. 168:1291-1309.

Interpretive Summary: We investigated genetic variation within and among 11 populations of Iris hexagona at its southern limits in the Florida peninsula using 19 DNA repeat molecular markers. All of the populations showed evidence clonal reproduction. Two populations are predominantly clonal, one from the Caloosahatchee drainage west of Lake Okeechobee, and the other from the Big Cypress Swamp. The populations are predominantly out-crossing, with high levels of heterozygosity, and show a highly significant pattern of isolation by distance that breaks down at the local level where gene flow is higher. Most of the genetic variation is within populations. Genetic distance resolves four clusters: three in the Caloosahatchee Valley, and one in Big Cypress Swamp. All of the populations exhibit evidence of a recent bottleneck attributable to founder effects. We suggest that the two predominantly clonal populations may be artifacts of deliberate cultivation by humans.

Technical Abstract: We investigated genetic variation within and among 11 populations of Iris hexagona at its southern limits in the Florida peninsula using 19 microsatellite loci. All of the populations contain varying numbers of identical multi-locus genotypes, indicative of clonal reproduction. Two populations are predominantly clonal, one from the Caloosahatchee drainage west of Lake Okeechobee, and the other from the Big Cypress Swamp. The populations are predominantly out-crossing, with high levels of heterozygosity, and show a highly significant pattern of isolation by distance that fits a modified stepping stone model. This pattern breaks down at the local level, however, where metapopulation dynamics may exert a stronger effect on patterns of genetic diversity. Most of the genetic variation is within populations. Genetic distance resolves four clusters: three in the Caloosahatchee Valley, and one in Big Cypress Swamp. However, the populations are strongly enough differentiated that frequency-based genetic structure analysis resolves seven populations. All of the populations exhibit evidence of a recent bottleneck, which we attribute to founder effects, given the low migration rate of the species and the high degree of population differentiation, as well as the Holocene geological history of the Florida peninsula. We hypothesize that the two predominantly clonal populations may be artifacts of deliberate cultivation by humans.