title: Growth and survival across a gap-understory gradient: Contrast in performance of sexually vs. clonally produced offspring.
abstract: Sexually and clonally produced offspring may respond to environmental heterogeneity by growing and surviving at different rates. In forest understories, the availability of light ranges from low in shaded, closed canopy to high in tree-fall gaps. We experimentally investigated the growth and survival of both types of offspring in three treatments (gap centers, gap edges, and shaded understory) over 16 months. We expected the demographic performance of both types of offspring to be highest in the centers of gaps and lowest in the shaded understory. However, we expected seedlings to be more sensitive to the gradient in light (larger difference in growth and survival between light levels) than vegetative offspring because of their small size and lack of connection to maternal resources. Both offspring types grew fastest and obtained their largest sizes in gap centers. Contrary to our expectations, offspring types differed in which light conditions favored highest survival. Seedlings survived best in gap centers, while vegetative offspring had their highest survival in the shaded understory. In agreement with our hypothesis, survival and growth of seedlings were more sensitive to light availability, showing a large difference in growth and survival between light levels, compared to vegetative offspring.
authors.affiliation: Department of Biology, University of Miami, P.O. Box 249118, Coral Gables, Florida 33124 USA.
authors.forename: David P
authors.initials: DP
authors.lastname: Matlaga
authors.forename: Carol C
authors.initials: CC
authors.lastname: Horvitz