Download The Science of Classification

MODERN
TAXONOMY
Techniques that are used today to
provide information about an
organism and its relatives.
Phylogeny
This is a field of
biology where
scientists study the
evolutionary history
of living organisms.
Phylogenists often
study the fossil
record and analyze
connections to the
past.
Today most scientists …….
• recognize that organisms have
changed over time.
• accept evolution as the basis for
classification.
What is a fossil ?
• A fossil is a cast or mold of an
organism preserved in rock that
formed where the organism
died.
• A fossil could also consist of
the organism itself in ice,
amber, or in volcanic glass.
• A fossil could also consist of
tracks (footprints), seeds, or
skeleton preserved in deposits.
1
Methods and Techniques
used by today’s taxonomists.
1. Fossil Records: Fossils provide evidence that show
how plants and animals are related by preserving
structures that can be studied and compared.
2. Homologous
structures:
Homologous structures
are parts in different
animals that show
similarities in their
structure.
Methods and Techniques used by
today’s taxonomists. (cont’d)
4. Comparative
biochemistry:
Taxonomists today now study
the chemistry of blood,
enzymes and other specific
substances produced by
animals and plants. Example The hemoglobins in the blood
cells of gorillas and humans
are the same except for one
amino acid.
Methods and Techniques used by
today’s taxonomists. (cont’d)
3. Comparative
embryology:
Taxonomists study
the patterns of
development before
birth. Embryos of
organisms believed to
be closely related
show similar patterns
of development.
Methods and Techniques used by
today’s taxonomists.
5. Comparative DNA and RNA:
Scientists now study DNA and RNA
structure to see their similarities
amoung organisms. We know that
the DNA of humans and
chimpanzees is 99% identical. We
also know that the DNA between
humans and other mammals
(dog,horses,whales,bats,etc) is only
about 80% identical.
2
In summary some of the methods used
to determine characteristics for
classification purposes are:
•
•
•
•
•
How are these animals
compared?
1. Fossil records
2. Homologous structures
3. Comparative embryology
4. Comparative biochemistry
5. Comparative DNA / RNA (genetics)
The End
3