1. MODERN TAXONOMY
Techniques that are used today to provide information about an organism.

2. Today most scientists …….
recognize that organisms have changed over time.
accept evolution as the basis for classification.

3. Phylogeny
This is a field of biology where scientists study the evolutionary history of living organisms. Phylogenists often study fossils.

4. 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.

5. 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. (Please turn to page 475 of your text for example)

6. 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. (see page 477 in your text)

7. 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.
Much research today focuses on comparing sequences of amino acids in organisms to reveal relationships. What determines the sequence of these amino acids ?
DNA

8. Methods and Techniques used by today’s taxonomists. (cont’d)
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.

9. Methods and Techniques used by today’s taxonomists. (cont’d)
6. Function: what the organism does, place in the ecosystem.
7. Behavior: series of activities performed by an organism in response to stimuli.
8. Nutrition: what an organism eats

10. Final Thoughts
It is important to recognize that a taxonomic classification system is not a fact. Classification is based on opinions and as a result there are a number of ways in which organisms can be grouped.