| Abstract: | Carnivory has evolved independently at least six times in fiveangiosperm orders. In spite of these independent origins, thereis a remarkable morphological convergence of carnivorous planttraps and physiological convergence of mechanisms for digestingand assimilating prey. These convergent traits have made carnivorousplants model systems for addressing questions in plant moleculargenetics, physiology, and evolutionary ecology. New data showthat carnivorous plant genera with morphologically complex trapshave higher relative rates of gene substitutions than do thosewith simple sticky traps. This observation suggests two alternativemechanisms for the evolution and diversification of carnivorousplant lineages. The ‘energetics hypothesis’ positsrapid morphological evolution resulting from a few changes inregulatory genes responsible for meeting the high energeticdemands of active traps. The ‘predictable prey capturehypothesis’ further posits that complex traps yield morepredictable and frequent prey captures. To evaluate these hypotheses,available data on the tempo and mode of carnivorous plant evolutionwere reviewed; patterns of prey capture by carnivorous plantswere analysed; and the energetic costs and benefits of botanicalcarnivory were re-evaluated. Collectively, the data are moresupportive of the energetics hypothesis than the predictableprey capture hypothesis. The energetics hypothesis is consistentwith a phenomenological cost–benefit model for the evolutionof botanical carnivory, and also accounts for data suggestingthat carnivorous plants have leaf construction costs and scalingrelationships among leaf traits that are substantially differentfrom those of non-carnivorous plants. Key words: Carnivorous plants, competition, construction costs, cost–benefit model, Darwin, energetics, niche overlap, phylogeny, prey capture, universal spectrum of leaf traits
Received 6 May 2008; Revised 5 June 2008 Accepted 16 June 2008 |
