DOI 10.1007/s00442-007-0936-3PHYSIOLOGICAL ECOLOGY- ORIGINAL PAPER Adaptive radiation of photosynthetic physiology in the Hawaiian lobeliads: dynamic photosynthetic responses

Abstract Hawaiian lobeliads have radiated into habitats from open alpine bogs to densely shaded rainforest interi-ors, and show corresponding adaptations in steady-state photosynthetic light responses and associated leaf traits. Shaded environments are not uniformly dark, however, but punctuated by sunXecks that carry most of the photosyn-thetically active light that strikes plants. We asked whether lobeliads have diversiWed in their dynamic photosynthetic light responses and how dynamic responses inXuence daily leaf carbon gain. We quantiWed gas exchange and dynamic light regimes under Weld conditions for ten species repre-senting each major Hawaiian sublineage. Species in shadier habitats experienced shorter and less numerous sunXecks: average sunXeck length varied from 1.4 § 1.7 min for Cya-nea Xoribunda in shaded forest understories to 31.2