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THE CAUSES OF VARIATION IN TREE SEEDLING TRAITS: THE ROLES OF ENVIRONMENTAL SELECTION VERSUS CHANCE
Author(s) -
Marks Christian O.
Publication year - 2007
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1742-4658.2007.00021.x
Subject(s) - biology , trait , variation (astronomy) , divergence (linguistics) , selection (genetic algorithm) , ecology , evolutionary biology , genetic variation , ecological selection , convergence (economics) , biodiversity , perspective (graphical) , genetics , mathematics , linguistics , philosophy , physics , artificial intelligence , astrophysics , computer science , gene , economics , programming language , economic growth , geometry
A key aspect of biodiversity is the great quantitative variation in functional traits observed among species. One perspective asserts that trait values should converge on a single optimum value in a particular selective environment, and consequently trait variation would reflect differences in selective environment, and evolutionary outcomes would be predictable. An alternative perspective asserts that there are likely multiple alternative optima within a particular selective environment, and consequently different lineages would evolve toward different optima due to chance. Because there is evidence for both of these perspectives, there is a long‐standing controversy over the relative importance of convergence due to environmental selection versus divergence due to chance in shaping trait variation. Here, I use a model of tree seedling growth and survival to distinguish trait variation associated with multiple alternative optima from variation associated with environmental differences. I show that variation in whole plant traits is best explained by environmental differences, whereas in organ level traits variation is more affected by alternative optima. Consequently, I predict that in nature variation in organ level traits is most closely related to phylogeny, whereas variation in whole plant traits is most closely related to ecology.