Establishment of Evolutionary Relationships
Traditional single-gene studies are effective in establishing phylogenetic trees among closely related organisms, but have drawbacks when comparing more distantly related organisms or microorganisms. This is because of lateral gene transfer, convergence, and varying rates of evolution for different genes. By using entire genomes in these comparisons, the anomalies created from these factors are overwhelmed by the pattern of evolution indicated by the majority of the data. Through phylogenomics, it has been discovered that most of the photosynthetic eukaryotes are linked and possibly share a single ancestor. Researchers compared 135 genes from 65 different species of photosynthetic organisms. These included plants, chromalveolates, rhizarians, haptophytes and cryptomonads. This has been referred to as the Plants+HC+SAR megagroup. Using this method, it is theoretically possible to create fully resolved phylogenetic trees, and timing constraints can be recovered more accurately. However, in practice this is not always the case. Due to insufficient data, multiple trees can sometimes be supported by the same data when analyzed using different methods.
Read more about this topic: Phylogenomics
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