Chapter 28
Viruses, Underestimated Drivers of Ecology
and Evolution of Life
Antje Lauer
Abstract Viruses are the most understudied microbial agents on our planet; their
polyphyletic origin is still shrouded in mysteries. At least some RNA viruses appear
to have evolved from self-replicating molecules in the so-called RNA-world that
researchers believe to have existed before DNA evolved billions of years ago. Many
theories of viral origin and evolution are debated and, even though the fossil record
of viruses is basically non-existent in the traditional sense, modern phylogenetic
sequencing and electron microscopy have revealed astonishing secrets of viral
diversity regarding genome, shape, and size and elucidated many sophisticated
mechanisms behind their ability to thrive and replicate as obligate parasites,
enslaving their host’s replication machinery for their own purposes. Furthermore,
evidence exists that many proviruses have evolved with their host, some being part
of the so-called junk DNA that we find in prokaryotes and eukaryotes alike, whereas
others shaped the evolution of multicellular species becoming even necessary for the
survival of the host. With the detection of giant viruses with large genomes including
genes coding for replication, one might consider a fourth domain of life for these
agents. Ignored and despised, these representatives of the microbial world have been
significantly involved in shaping the evolution and ecology of all living species on
Earth, in the past, currently, and will continue so in the future. Therefore, viruses, as
well as viroids, deserve to be considered as being part of the foundation stone of
Earth’s biosphere.
28.1 Introduction
It is undebated that microbial species on Earth are the true rulers of the biosphere;
without them and their involvement in biogeochemical cycles, life, as we know it,
would not be sustainable, not even exist. Thanks to the dedication and diligence of
uncounted researchers, we are now aware of the microbial world around us. It has
A. Lauer (*)
California State University Bakersfield, Department of Biology, Bakersfield, CA, USA
e-mail: alauer@csub.edu
© Springer Nature Switzerland AG 2021
C. J. Hurst (ed.), Microbes: The Foundation Stone of the Biosphere, Advances in
Environmental Microbiology 8, https://doi.org/10.1007/978-3-030-63512-1_28
613
Viruses, Underestimated Drivers of Ecology
and Evolution of Life
Antje Lauer
Abstract Viruses are the most understudied microbial agents on our planet; their
polyphyletic origin is still shrouded in mysteries. At least some RNA viruses appear
to have evolved from self-replicating molecules in the so-called RNA-world that
researchers believe to have existed before DNA evolved billions of years ago. Many
theories of viral origin and evolution are debated and, even though the fossil record
of viruses is basically non-existent in the traditional sense, modern phylogenetic
sequencing and electron microscopy have revealed astonishing secrets of viral
diversity regarding genome, shape, and size and elucidated many sophisticated
mechanisms behind their ability to thrive and replicate as obligate parasites,
enslaving their host’s replication machinery for their own purposes. Furthermore,
evidence exists that many proviruses have evolved with their host, some being part
of the so-called junk DNA that we find in prokaryotes and eukaryotes alike, whereas
others shaped the evolution of multicellular species becoming even necessary for the
survival of the host. With the detection of giant viruses with large genomes including
genes coding for replication, one might consider a fourth domain of life for these
agents. Ignored and despised, these representatives of the microbial world have been
significantly involved in shaping the evolution and ecology of all living species on
Earth, in the past, currently, and will continue so in the future. Therefore, viruses, as
well as viroids, deserve to be considered as being part of the foundation stone of
Earth’s biosphere.
28.1 Introduction
It is undebated that microbial species on Earth are the true rulers of the biosphere;
without them and their involvement in biogeochemical cycles, life, as we know it,
would not be sustainable, not even exist. Thanks to the dedication and diligence of
uncounted researchers, we are now aware of the microbial world around us. It has
A. Lauer (*)
California State University Bakersfield, Department of Biology, Bakersfield, CA, USA
e-mail: alauer@csub.edu
© Springer Nature Switzerland AG 2021
C. J. Hurst (ed.), Microbes: The Foundation Stone of the Biosphere, Advances in
Environmental Microbiology 8, https://doi.org/10.1007/978-3-030-63512-1_28
613