Diversity of Life
•Major groupings
•How many organisms on earth
• viruses
Diversity of Life - Kingdoms
• Aristotle to Linneus 1860 – Animalia,
Plantae
Chlorophyll vs none = method of getting energy
1850 Haeckel – add Protista (one celled)
Separate them as both plants and animals and some in between
(Euglena – a motile one celled organism with chlorophyll
Discovered Volvox in
1700
Antonie van Leeuwenhoek
(1632-1723) the first person to
study protozoa and bacteria
1937 Charlton – procaryotes,(bacteria)
eucaryotes(true cells, with nucleus)
Eucaryotes include animals, plants and
protista (or proctista)
Procaryote
Bacteria – ‘nothing’ inside
Eucaryote
Amoeba; nuclei, organelles,
etc.
1959 – Whittaker – Fungi are fifth
kingdom
No chlorophyll, not motile, multicellular, eucaryotic
1990 – Woese, splits procaryota into true bacteria = eubacteria, and
archaebacteria (6th kingdom) also new category = Domains, archaea,bacteria
and eukarya. Separation based on biochemistry, not appearance.
Viruses: not classified – are they fragments of higher
organisms, or remnants of very early life?? More later.
What belongs in the kingdom plantae?
Original:If it is photysynthetic it is a plant.
Today;
1. But if it is a procaryote, and green, it is not a plant
(photsynthetic bacteria)
2. If it is one celled eucaryote (euglena), it is not a plant.
3. If it has no embryo, it is not a plant (so all marine and fresh
water algae are no longer plants.)
Why = cladistics in part. Attempt to find a common ancestor and
recognition that photosynthesis is very old and may have arisen
more than once.
Euglena – a protist
‘seaweed’ – protist
Photosynthetic bacteria = eu or archebacteria
Note: multicellular algae are now protists !!!
How many species are there on earth?
Described species: 1.6 million.
Most species are arthropods.
About 1 million are insects.
How many species are
undescribed ?.
How do we estimate the number of
undescribed species?
Two previously unknown monkey species,
discovered in the Amazon in 2002
Discovery rate for birds, mammals; 1-3 per
year – big, lots of researchers.
Discovery rate for insects: higher and fewer
researchers.
http://news.nationalgeographic.com/news/2002/06/0625_020624_0624TVprimate.html
Is the world full?
Are all niches utilized??
1. Oceans
2. land invasion
3. Air invasion
Fossil record:
Poorer farther
back you go –
Major
fluctuations
Most unidentified species are small insects.
Another strategy: species accumulation curves
How many species are undescribed?
The great killing experiment
•Find an tropical forest area about
to be logged
• gas a tree and catch all the bugs
• sort the beetles to species
• do this for several tree species
• identify beetles unique to each
tree.
•You know ½ of all animals are
insects, ¼ of all insects are beetles
• you know how many different
trees in the tropics
•Tree species x unique beetles x ½
x ¼ x 1.5 million (number of
described species) = 10 to 20
million species undescribed
This is the basis for the
statement that 100s of species
go extinct every day; they are
tropical insects and it is due to
tropical deforestation.
A whole world underground that is
mostly unexplored...
Viruses
• Tiny (23 billion needed to become visible)
• Many shapes
• Consist of an outer capsule (protein) and
an inner dna or rna molecule.
• Obligate parasites = use a host cell’s
machinery to make copies of selves.
Adenovirus (pink eye)
Hanta virus
Flu virus
Influenza virus
hiv virus
Papilloma virus (warts)
A submicroscopic infectious
agent that is unable to grow or
reproduce outside a host cell. It
is non-cellular but consisting of a
core of DNA or RNA surrounded
by a protein coat.
Viruses: extremely small, varied in shape.
Origins
• Virus are extremely varied, some with as
few as 4 genes, some with as many as
200.
• Believed to have several origins, not a
single one.
• Thought to be ‘fragments’ from living cells
and go back to first bacteria.
Extreme abundance of viruses.
One teaspoon of ocean water contains 10 to 100 million virus particles, ten
times the number of bacteria.
What are viruses?
“old view” = obligate parasites on cells, therefore, must have come into
existence after cellular life. They are ‘deccomposition fragments’ of living
cells.
New view = see evolution of viruses or viruses and evolution
The ancient Virus World and evolution of cells
Eugene V Koonin1
, Tatiana G Senkevich2
and Valerian V Dolja3
1 National Center for Biotechnology Information, National Library of Medicine, USA
2 Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20894, USA
3 Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR 97331, USA
• The extraordinary diversity of viruses
• Viruses are ubiquitous companions of cellular life forms:
it appears that every cellular organism studied has its
own viruses or, at least, virus-like selfish genetic
elements [1]. Recent environmental studies have shown
that viruses, primarily, bacteriophages, are "most
abundant biological entities on the planet" [2], with the
total number of virus particles exceeding the number of
cells by at least an order of magnitude [3,4]. Viruses
actively move between biomes and are thought to be
major agents of evolution by virtue of their capacity to
operate as vehicles of horizontal gene transfer (HGT) [5].
“Each teaspoon of weawater contains 10 – 100 million viruses (also 1-1million bacteria.
Effect on marine ecosystems?
Marine bacterioplankton = total weight of all other ocean organisms
and do most of the oceans photosynthesis
20% a day destroyed by viral infection – carbon not eaten but released.
We outline a scenario of the origin of the main classes of viruses in
conjunction with a specific model of precellular evolution under which the
primordial gene pool dwelled in a network of inorganic compartments.
Somewhat paradoxically, under this scenario, we surmise that selfish
genetic elements ancestral to viruses evolved prior to typical cells, to
become intracellular parasites once bacteria and archaea arrived at the
scene. Selection against excessively aggressive parasites that would kill off
the host ensembles of genetic elements would lead to early evolution of
temperate virus-like agents and primitive defense mechanisms, possibly,
based on the RNA interference principle. The emergence of the eukaryotic
cell is construed as the second melting pot of virus evolution from which the
major groups of eukaryotic viruses originated as a result of extensive
recombination of genes from various bacteriophages, archaeal viruses,
plasmids, and the evolving eukaryotic genomes. Again, this vision is
predicated on a specific model of the emergence of eukaryotic cell under
which archaeo-bacterial symbiosis was the starting point of eukaryogenesis,
a scenario that appears to be best compatible with the data.
Evolution of the virus world: origin of
the main lineages from the primordial
gene pool. Characteristic images of
RNA and protein structures are shown
for each postulated stage of evolution,
and characteristic virion images are
shown for the emerging classes of
viruses. Thin arrows show the postulated
movement of genetic pools between
inorganic compartments. Block arrows
show the origin of different classes of
viruses at different stages of pre-cellular
evolution.
Koonin et al. Biology Direct 2006
1:29 doi:10.1186/1745-6150-1-29