Persistence of Neighborhood Demographic Influences over Long Phylogenetic Distances May Help Drive Post-Speciation Adaptation in Tropical Forests.
Studies of forest dynamics plots (FDPs) have revealed a variety of negative density-dependent (NDD) demographic interactions, especially among conspecific trees. These interactions can affect growth rate, recruitment and mortality, and they play a central role in the maintenance of species diversity in these complex ecosystems. Here we use an equal area annulus (EAA) point-pattern method to comprehensively analyze data from two tropical FDPs, Barro Colorado Island in Panama and Sinharaja in Sri Lanka. We show that these NDD interactions also influence the continued evolutionary diversification of even distantly related tree species in these FDPs. We examine the details of a wide range of these interactions between individual trees and the trees that surround them. All these interactions, and their cumulative effects, are strongest among conspecific focal and surrounding tree species in both FDPs. They diminish in magnitude with increasing phylogenetic distance between heterospecific focal and surrounding trees, but do not disappear or change the pattern of their dependence on size, density, frequency or physical distance even among the most distantly related trees. The phylogenetic persistence of all these effects provides evidence that interactions between tree species that share an ecosystem may continue to promote adaptive divergence even after the species' gene pools have become separated. Adaptive divergence among taxa would operate in stark contrast to an alternative possibility that has previously been suggested, that distantly related species with dispersal-limited distributions and confronted with unpredictable neighbors will tend to converge on common strategies of resource use. In addition, we have also uncovered a positive density-dependent effect: growth rates of large trees are boosted in the presence of a smaller basal area of surrounding trees. We also show that many of the NDD interactions switch sign rapidly as focal trees grow in size, and that their cumulative effect can strongly influence the distributions and species composition of the trees that surround the focal trees during the focal trees' lifetimes.
Section of Ecology, Behavior and Evolution, Division of Biological Sciences, University of California San Diego, La Jolla, California 92093-0116, United States of America.
Christopher
C
Wills
Dept. of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States of America.
Kyle E
KE
Harms
Dept. of Ecological Modeling, UFZ-Helmholtz Centre for Environmental Research GmbH-UFZ, 04318 Leipzig, Germany.|German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Biodiversity Synthesis, Deutscher Platz 5e, 04103 Leipzig, Germany.
Thorsten
T
Wiegand
Department of Ecosystem Modelling, University of Göttingen, Büsgenweg 4, 37077 Göttingen, Germany.
Ruwan
R
Punchi-Manage
Dept. of Environmental Studies, University of California Santa Cruz, Santa Cruz, California 95064, United States of America.|Smithsonian Tropical Research Institute, Balboa, Ancón, Panamá 0843-03092.
Gregory S
GS
Gilbert
Smithsonian Tropical Research Institute, Balboa, Ancón, Panamá 0843-03092.
David
D
Erickson
Smithsonian Tropical Research Institute, Balboa, Ancón, Panamá 0843-03092.
W John
WJ
Kress
Smithsonian Tropical Research Institute, Balboa, Ancón, Panamá 0843-03092.|Dept. of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles 90095, California, United States of America.
Stephen P
SP
Hubbell
Dept. of Botany, Faculty of Science, University of Peradeniya, Peradeniya, 20400 Sri Lanka.
C V Savitri
CV
Gunatilleke
Dept. of Botany, Faculty of Science, University of Peradeniya, Peradeniya, 20400 Sri Lanka.
I A U Nimal
IA
Gunatilleke
D000064:Acclimatization; D000465:Algorithms; D003247:Conservation of Natural Resources / Q000379:methods; D065928:Forests; D061125:Genes, Chloroplast / Q000235:genetics; D005843:Geography; D008954:Models, Biological; D010176:Panama; D010802:Phylogeny; D011156:Population Density; D013045:Species Specificity; D013188:Sri Lanka; D014197:Trees / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D014329:Tropical Climate