Genetic divergence for physiological response to temperature between populations of a C3-C4 intermediate annual

Premise of research. Local adaptation ultimately arises as a result of adaptive divergence in phenotypic characters. Within a species, a large portion of the phenotypic traits that confer local adaptation must be physiological characters. Yet few studies consider adaptive divergence in physiological characters or estimate genetic variation within populations for physiological traits that may confer local adaptation. Here I test the hypothesis that there is genetic variation within and between populations of a C3-C4 intermediate for the CO2 compensation point (Γ) and other photosynthetic traits. In addition to local adaptation, population-level variation in photosynthetic characters of C3-C4 intermediates reflects the potential for evolution of more C4-like photosynthesis.

Methodology. I chose two populations of Mollugo verticillata, one from a relatively cool climate and one from a warm climate. I quantified variation within and between populations by measuring photosynthetic physiol...