ation with another eukaryote. There has been discussion as to how many times such secondary endosymbioses may have occurred, but a minimum estimate is twice. Interestingly there are also other convergences, notably in comparison between two endosymbioses involving a cryptomonad and a chloroarachniophyte and in both cases not only has there been a startling reduction in genome size but also in a highly convergent fashion.
Finally, in the wider context of evolutionary convergence it is worth noting that dramatic decreases in genome size are also seen in other types of endosymbiont, notably in the α-proteobacteria that are associated with sap-feeding insects, and also pathogenic bacteria. In these cases there are also parallelisms within the specific groups.
Cite this web page
Map of Life - "Chloroplast and mitochondrial plastid origins"
October 16, 2019