Evolutionary Aspects of Functional and Pseudogene Members of the Phytochrome Gene Family in Scots Pine

According to the neutral theory of evolution, mutation and genetic drift are the only forces that shape unconstrained, neutral, gene evolution. Thus, pseudogenes (which often evolve neutrally) provide opportunities to obtain direct estimates of mutation rates that are not biased by selection, and gene families comprising functional and pseudogene members provide useful material for both estimating neutral mutation rates and identifying sites that appear to be under positive or negative selection pressures. Conifers could be very useful for such analyses since they have large and complex genomes. There is evidence that pseudogenes make significant contributions to the size and complexity of gene families in pines, although few studies have examined the composition and evolution of gene families in conifers. In this work, I examine the complexity and rates of mutation of the phytochrome gene family in Pinus sylvestris and show that it includes not only functional genes but also pseudogenes. As expected, the functional PHYO does not appear to have evolved neutrally, while phytochrome pseudogenes show signs of unconstrained evolution.