Ecological Patterns and Processes in Sarracenia Carnivorous Pitcher Plant Fungi
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CitationBoynton, Primrose. 2012. Ecological Patterns and Processes in Sarracenia Carnivorous Pitcher Plant Fungi. Doctoral dissertation, Harvard University.
AbstractThe kingdom Fungi is taxonomically and ecologically diverse, containing an estimated 1.5 million species. Fungi include decomposers, pathogens, and plant and animal mutualists. Many fungi are microorganisms, and the processes shaping microbial diversity may be fundamentally different from those that shape plants and animals. However, ecologists do not yet fully understand how fungal species are distributed over space and time. Using fungi that inhabit the water of Sarracenia carnivorous pitchers, I describe inter and intraspecific fungal diversity and investigate the processes that shape fungal diversity. I introduce these concepts in Chapter 1. In Chapter 2, I describe changes in fungal species diversity over space and time. I enumerated fungal species in five Sarracenia populations across the United States and Canada, and show that thousands, but not hundreds of kilometers separate distinct fungal communities. I also sampled a single Sarracenia population over a Sarracenia growing season, and found that young fungal communities are significantly different from older fungal communities. Observed patterns correlate with environmental factors including temperature and pitcher pH, and with the presence or population structure of pitcher inhabiting arthropods. In Chapter 3, I describe dispersal of and competition among three common pitcher fungi. I tracked Candida glaebosa, Rhodotorula glutinis, and Pseudozyma aphidis appearances in pitchers in a single Sarracenia population, and show that different appearances reflect different dispersal times. I also describe interactions between dispersal and competition in microcosms: high numbers of propagules introduced into a microcosm give a competitive advantage to investigated fungi. In Chapter 4, I describe changes in genotype composition of a population of Candida glaebosa, which is widespread and abundant in pitchers, and disperses early in the season. I observed three C. glaebosa populations in five locations; C. glaebosa population structure does not reflect broader community structure as described in Chapter 2. Population structure instead correlates with host taxonomy, and I contrast inter and intraspecific diversity patterns and the processes that potentially cause such patterns.
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