Organizing Life’s Diversity

Classification To attempt to make sense out of all the living things on the earth scientists have tried to organize them into ‘like’ groups. This attempt has been termed ‘CLASSIFICATION’

Taxonomy The branch of biology that groups and names organisms. Scientist who do this are called taxonomists.

Aristotle The Greek philosopher ARISTOTLE ( B.C.) developed the first widely accepted biological classification system.

Considered the Father of Taxonomy. Aristotle classified all the organisms he knew about in to 2 groups:

–Plants Herbs, Shrubs, Trees –Animals Air, Land, Water

It was useful but did not group organisms according to their evolutionary history. Bats, Bees, Birds all classed together. Are chickens land or air animals? Duck air or water animals?

Linnaeus (1707 – 1778) Carolus Linnaeus developed a classification system that replaced Aristotle’s because it was more useful. We still use it today.

Linnaeus based his system on physical and structural similarities of organisms. The groupings revealed the relationships of organisms.

Bats fly like birds but have hair and produce milk for their young so they are classified as mammals rather than birds.

Binomial Nomenclature Linnaeus used a 2 word naming system to name each organism he classified. The system is called Binomial Nomenclature

The first name identifies the genus of the organism. The first letter of the name is ALWAYS capitalized. The second name identifies the species, usually descriptive, it does not contain capitols.

The scientific name of a species is always 2 names. Example: Humans have the scientific name of Homo sapiens. Notice the name is italicized. If you are writing the name by hand underline it.

Homo is the genus. Genus means a group of similar organisms. Sapiens means ‘wise’ Wise is the descriptive name.

All scientific names are Latin names or Latinized names. Latin is a language that is not longer in use so it does not change, making it great for naming organisms.

The reason we do not use common names like sea horse is that they can be misleading. A sea horse is a fish not a horse.

The house sparrow (America) The gorrion (Spain) The musch (Holland) The hussparf (Sweden) Same Bird different name. Can get confusing.

Taxonomy Today Expanding on Linnaeus’s work taxononists try to identify natural relationships of organisms.

They use: External, internal, geographical distribution and chemical makeup to reveal possible evolutionary relationships.

Helps find Relationships Birds have hollow bones, some dinosaurs have hollow bones too. This suggests that birds and dinosaurs might be more closely related than reptiles and dinosaurs.

Helps Poison Control The folks at Poison Control have a list of all toxic substances.

If a kid eats a berry from a plant you can call poison control and describe the plant and because taxonomist have classified all poisonous plants they can let you know if what the kid ate is poisonous.

Taxonomy and the Economy If a taxonomist knows a certain pine tree has a chemical in it’s bark that makes a good disinfectant related trees might also.

How Living things are Classified Biologists group organisms, then subdivide the groups into smaller groups, each smaller group is more similar than the previous group. Each group is called a taxon.(plural, taxa)

7 taxa are used today. Listed from broadest to narrowest. –Kingdom Phylum –Class »Order »Family »Genus »Species

See page 459 in text. Kingdom is a taxon of similar phyla. Phylum is a taxon of similar classes. Class is a taxon of similar families. Family is a taxon of similar genera. Genus is a taxon of similar species.

A species is a group of organisms that can mate with one another to produce fertile offspring but cannot mate successfully with members of another group.

PSL 17-1 page 457 # 1-4. SA 17.1 page 459 # 1-5.

The Six Kingdoms How do scientist determine how organisms are related and what taxon to place them into? It’s no easy task.

Sometimes an organism is classed one way then years later after more research is done taxonomists move the organism to another taxon.

5 ways to determine relations

Structural similarities: All cats have retractable claws, fore limbs with 5 toes and hind limbs with 4 toes. Lynx and bobcats have 28 teeth Cougars have 30 as well as all other lions.

Breeding Behavior Two species of frog: Hyla versicolor and H. chrysoscelis. Both look similar Both live in the same area Both eat the same foods

Hyla versicolor makes a different sound during mating season than Hyla chrysoscelis therefore they only attract mates from their own group.

Geographical distribution The wide variety of finches found on the Galapagos islands suggests that they may have a common ancestor that lived in South America and flew to the islands.

Once there the finches spread into different niches and evolved into many distinct species.

Chromosome comparisons Organisms that have chromosomes that are almost identical are probably more related than organism with vastly different chromosomes.

Brussel sprouts, cauliflower, cabbage, kale and broccoli have almost identical chromosomes. Suggesting a close relationship.

Biochemistry Closely related species have similar DNA sequences and, therefore similar proteins. In general the more inherited nucleotide sequences that two species share the more closely related they are.

BIO chem Lab. Amino acid sequences.

Phylogeny The evolutionary history of a species. Species that share a common ancestor also share an evolutionary history.

Cladistics Assumes that as groups of organisms diverge (grow apart) and evolve from a common ancestor they retain some unique inherited characteristics.

Cladogram A model of the phylogeny of a species. Shows a probable phylogeny of a group of organisms from ancestral groups.

Fanlike Model Help you find relationships between modern and extinct species. May communicate the time organisms became extinct, or relative number of species in a group.

Mini Lab 17-2 Page 467 Fill out Six Kingdom content frame. With Teacher.

Characteri stic EubacteraArchae- bacteria ProtistaFungiPlantaeAnimalia Cell Type Body Form Method of Obtaining Food Presents of Complex Organ Systems

Character istic Eubacter a Archaeba cteria ProtistaFungiPlantaeAnimalia Cell TypeProkaryo tic eukaryote s Body Form Single Cell Single Cell Single Cell Multi & Single Cell Multi Cell Multi Cell Method of Obtainin g Food Hetero Auto Trophic Hetero Chemo Trophic Hetero Auto Trophic Hetero Trophic Auto Trophic Hetero Trophic Presents of Complex Organ Systems NO YES

Assignment SA 17.2 Page 473 #1-5. CA17 page 477 #1-25. Vocabulary (ALL) Page 477 LAB Making a Dichotomous key.