Evolutionary ecology of carbon acquisition in plants: kin recognition and niche partitioning in sibling competition

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Plants sense and integrate information, changing their growth and development in response to their environment. Identity recognition is an emerging field in plant ecology, with competitive, reproductive and defensive traits showing plasticity to the identity of neighbours. Evolutionary theory suggests that the ability to identify relatives can increase fitness, since it allows individuals to favour relatives that share their genes. The findings from my lab that group root allocation differs between sibling and stranger groups indicate that plants may have the ability to recognize and favour their relatives. In this research we will look in greater detail at the individual phenotype of plants in sibling/stranger groups to determine whether kin recognition responses can be found in multiple traits: individual root allocation, detailed root morphology and root architecture, and spatial use of the soil by plants in competition. Once we have individual measures for root traits, we can determine the fitness consequences of kin recognition. Kin selection predicts that siblings would be expected to cooperate with each other, and therefore have higher fitness than strangers. A second theory, the niche partitioning hypothesis predicts that because strangers are expected to differ more in niche use than siblings, strangers will compete less than siblings, and therefore have higher fitness than siblings. In plants, these predictions have been tested by growing plants in groups of siblings or strangers, and then measuring performance or fitness. However, results that support both theories are found. If these processes co-occur, then fitness measures cannot provide a definitive test for kin selection. We will test these prediction directly in functional traits associated with competition and resource acquisition. We propose to determine if traits that show kin recognition increase group fitness at the cost of individual fitness, and if any traits show selection consistent with niche partitioning. This research will provide training for 3 Ph.D. students, 3 M.Sc. students, 10-20 undergraduate thesis students, and 10 undergraduate research assistants.