Although today's humans may harbor mixed feelings about our species' recent track record in settling Earth's land masses, wiping out numerous other life forms, turning forests into farmland and achieving exponential population growth, our success viewed in biological terms has been spectacular.
And while other life forms may be more numerous individually, more obviously assertive or more diverse, the vast majority couldn't exist without the oxygen that plants supply through photosynthesis.
Nevertheless, care should be taken when comparing data between studies as genetic diversity depends on numerous factors, namely life history, breeding system, growth life forms, geographical range and type of molecular method used (Powell et al. 1996; Nybom 2004).
The palm-domain RdRps and RTs are excluded from the regular life cycles of cellular life forms, although most eukaryotic genomes encompass numerous copies of RT-containing retroelements, and prokaryotes have some such elements as well [ 31, 32].
Comparisons with other studies are difficult since genetic diversity depends on numerous factors, such as life history, breeding system, growth life forms, geographical range and even the type of molecular method used (Powell et al. 1996; Nybom 2004).
The observation that giant viruses encompass many ancestral genes shared with the smaller members of " Megavirales" constrains the fourth-domain hypothesis to a specific version under which a viral ancestor of the giant viruses reproduced in a host that belonged to a fourth domain of cellular life and acquired numerous genes, including some that are universal in cellular life forms.
Viruses are barely life forms.
Tree of life, diversity of life forms.
Viruses are curious life forms.
Let other life forms flourish.
