Grant: Discovery Grants Program - Individual

Diatoms (microscopic marine plants) are extremely important ecologically (up to 20% of global primary production is due to diatoms) and economically (producing amnesic shellfish poisoning). It is also the most species rich group of microscopic plants with an estimated 200,000+ species. Diatoms are a relatively new evolutionary arrival, suggesting a high rate of speciation. The mechanism(s) of diatom speciation are unknown. The long term objective of my research is to advance the understanding of diatom evolution and speciation through investigation of the reproductive processes, sex-cell structures and breeding systems in key diatom lineages. In the current proposal, the short term objectives are to test hypotheses explaining how similar morphology might have evolved in unrelated groups and how informative the structure of diatom sex-cells is in inferring evolution of individual lineages. We also want to find out if the nuclear encoded internal transcribed spacer 2 (ITS2) RNA transcript secondary structure is consistent with other biota and whether compensatory base changes (CBCs) in the strongly conserved regions of the transcript may predict sexual incompatibility in diatoms, thus helping to identify target organisms for breeding experiments. Finally we plan to conduct the first ever investigation of pattern of inheritance in diatoms, using crosses between first generation progeny including putative homozygous recessive and heterozygous dominant partners. Our work will contribute to a better understanding of diatom evolution, genetics and ecology (including economically important, cryptic or harmful species). We know very little regarding the frequency or relative importance of any of these processes in the life histories of most marine centric diatoms. In light of scarcity of data and diversity of theories regarding diatom ecology and evolution, experimental data is obviously needed.