title: A two-generation analysis of pollen pool genetic structure in flowering dogwood, Cornus florida (Cornaceae), in the Missouri Ozarks.
abstract: Anthropogenic landscape change can disrupt gene flow. As part of the Missouri Ozark Forest Ecosystem Project, this study examined whether silvicultural practices influence pollen-mediated gene movement in the insect-pollinated species, Cornus florida L., by comparing pollen pool structure (Φ(st)) among clear-cutting, selective cutting, and uncut regimes with the expectation that pollen movement should be least in the uncut regime. Using a sample of 1500 seedlings-10 each from 150 seed parents (43 in clear-cut, 74 in selective, and 33 in control sites) from six sites (each ranging from 266 to 527 ha), eight allozyme loci were analyzed with a pollen pool structure approach known as TwoGener (Smouse et al., 2001; Evolution 55: 260-271). This analysis revealed that pollen pool structure was less in clear-cut (Φ(C) = 0.090, P < 0.001) than in uncut areas (Φ(U) = 0.174, P < 0.001), with selective-cut intermediate (Φ(S) = 0.125, P < 0.001). These estimates translate into more effective pollen donors (N(ep)) in clear-cut (N(ep) = 5.56) and selective-cut (N(ep) = 4.00) areas than in uncut areas (N(ep) = 2.87). We demonstrate that Φ(C) ≤ Φ(S) ≤ Φ(U), with Φ(C) significantly smaller than Φ(U) (P < 0.034). The findings imply that, as long as a sufficiently large number of seed parents remain to provide adequate reproduction and to avoid a genetic bottleneck in the effective number of mothers, silvicultural management may not negatively affect the effective number of pollen parents, and hence subsequent genetic diversity in Cornus florida.
authors.affiliation: Department of Ecology & Evolutionary Biology, University of California at Los Angeles, Box 951606, Los Angeles, California 90095-1606 USA;
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Sork
authors.forename: Peter E
authors.initials: PE
authors.lastname: Smouse
authors.forename: Victoria J
authors.initials: VJ
authors.lastname: Apsit
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Dyer
authors.forename: Robert D
authors.initials: RD
authors.lastname: Westfall