taxonomy & classification lecture grouping and naming organisms

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TAXONOMY & CLASSIFICATION LECTURE Grouping and Naming Organisms

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Page 1: TAXONOMY & CLASSIFICATION LECTURE Grouping and Naming Organisms

TAXONOMY & CLASSIFICATION

LECTURE

Grouping and Naming Organisms

Page 2: TAXONOMY & CLASSIFICATION LECTURE Grouping and Naming Organisms

DEFINITION

Taxonomy as defined by Webster’s dictionary is:

the process or system of describing the way in which

different living things are related by putting them in

groups

the study of the general principles of scientific

classification

orderly classification of plants and animals according

to their presumed natural relationships

Page 3: TAXONOMY & CLASSIFICATION LECTURE Grouping and Naming Organisms

Taxonomy is used to help scientists to universally name and classify organisms.

Why do we need to classify things?We classify organisms so that we can understand how they relate to one another. We organize them into groups that have biological significance.

Why is Taxonomy so important?So that everyone uses the same name and same naming system for all organisms worldwide

Page 4: TAXONOMY & CLASSIFICATION LECTURE Grouping and Naming Organisms

EARLY EFFORTS AT NAMING

A. Early naming efforts were very confusing and

the names were extremely long and detailed.a) Early naming systems have been traced

back as far as 1500 B.C.E. from the early Egyptians

b) Early nomenclature (500 C.E. to 1700 C.E.) example: “Oak with deeply divided leaves that have no hairs on their undersides and no teeth around their edges”

Page 5: TAXONOMY & CLASSIFICATION LECTURE Grouping and Naming Organisms

WHAT DO WE USE TODAY?

B. The Linnaeus system is the system that we use todaya) Created by Carolus Linnaeus in 1735b) Linnaeus’s system is a binomial nomenclature which is

a two-word naming systemc) A taxon is a group or level of organization within a

taxonomic category d) The Linnaeus system uses seven taxonomic categories:

a) Kingdom, phylum, class, order, family, Genus & speciesb) The scientific name is Genus species

Page 6: TAXONOMY & CLASSIFICATION LECTURE Grouping and Naming Organisms
Page 7: TAXONOMY & CLASSIFICATION LECTURE Grouping and Naming Organisms

WHAT DO WE USE TODAY?

C.Although we use the Linnaeus taxonomic

system, we have eight taxonomic categories, and

those categories could also have sub-categoriesa) Domain, kingdom, phylum, class, order,

family, Genus, and speciesa) example: Canis lupis

b) Sub-categories include sub-class and sub-order

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Page 9: TAXONOMY & CLASSIFICATION LECTURE Grouping and Naming Organisms
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D. Traditional Classificationa) Problems

1. Based on body structure and physical similarities.

2. Living things that are not related can share similar body structures due to convergent evolution and related organisms may have totally different body structures.a) Convergent evolution is the appearance

of apparently similar structures in organisms of different lines of descent.

E. Evolutionary Classification a) Scientists now group organisms into

categories that represent lines of evolutionary descent, not just physical similarities.

b) Cladistics is now the preferred analysis method which uses derived characteristics to connect lineages. This method is used to construct a cladogram

Page 11: TAXONOMY & CLASSIFICATION LECTURE Grouping and Naming Organisms

Traditional classification

Cladogram

Page 12: TAXONOMY & CLASSIFICATION LECTURE Grouping and Naming Organisms

F. Role of DNA and RNAa) With the advancement in DNA and

RNA we have been able to follow the genes of animals back through time.

b) A molecular clock allows us to use DNA to estimate the amount of time that two organisms have been evolving independently, or how long ago the two organisms separated on the evolutionary tree.

c) DNA advancement has also allowed us to ancestral relationships that we didn’t know existed:1. Example: yeast and humans both

have a gene that codes for myosin, which shows us that at one point we had a common ancestor with yeast.

Page 13: TAXONOMY & CLASSIFICATION LECTURE Grouping and Naming Organisms

A gene in an ancestral species

2 mutations

New mutations

Species A

Species B

Species C