Historical Effects and Sorting Processes as Explanations for Contemporary Ecological Patterns: Character Syndromes in Mediterranean Woody Plants

Ecological patterns are not only a consequence of adaptive processes, but also influenced by phylogenetic constraints, historical effects, and sorting processes. In contrast to the attention paid to the influence of phylogeny on interspecific ecological patterns, historical effects and sorting processes have been considered less frequently. This article shows that, for the woody flora of western Andalusia, southwestern Spain, these factors may be of substantial importance for explaining covariation among life-history traits (and associated "character syndromes") in plant communities. Multivariate analysis of the covariation across genera of 10 qualitative characters (related to general habit and reproductive biology) revealed a dominant life history-reproductive gradient (called "dimension 1") defining two distinct groups of genera and associated syndromes. Syndromes may largely be explained by reference to historical effects and species sorting processes, without recourse to adaptive explanations. Lineage age (as estimated from paleontological and biogeographical data) explained a significant proportion of intergeneric variation in position along dimension 1. Many character associations contributing to the syndromes vanished after the sample was split into groups based on lineage age, and those remaining occurred exclusively within the group of "old" (pre-Mediterranean) genera. No supporting evidence was found for the contribution of differential extinction of pre-Mediterranean genera to observed syndromes. Differential diversification of lineages as a function of life-history and reproductive characteristics did contribute significantly.