Thursday, February 28. Bell Work: On the picture.

Transcription

1 Thursday, February 28 Bell Work: On the picture. 1

2 Classification Chapter 17 This is a pangolin. Though it may not look like any other animal that you are familiar with, it is a mammal the same group of animals that includes dogs, cats, mixe and humans! 2

3 Utter chaos existed in the scientific world when it came to naming organisms. Scientists couldn't talk about different organisms from country to country There was no organization to the organisms (scientists would name them after themselves) 3

4 Biologists wanted to better understand organisms Taxonomy the science of naming and classifying organisms based on their different characteristics. Gave us a standard way to refer to a species. Classification the grouping of objects or information based on similarities. 4

5 Linnaeus's System 1700s Linnaeus s system is based on physical and structural similarities of organisms Organisms are placed into different levels, each level gets larger and more general. taxon a group of organisms in a classification system basic taxon is the species 5

6 Linnaeus's system gives each species a Scientific Name: Name given to all species to help identify them. This system is still used today 6

7 Binomial nomenclature A two word naming system that uses Latin First word identifies the genus of the organisms *genus group of physically similar species that are thought to be closely related. Second word is called the species descriptor Species desriptors can refer to: a specific trait of the species scientist who first described it native location of where they are found 7

8 How to write scientific names: The first letter of the genus should be capitalized. The species descriptor is NOT capitalized Written in italics or underlined. NEVER write the species descriptor by itself. Example: Quercus alba = white oak Tyto alba = barn owl Example: Humans are Homo sapiens 8

9 Why not just use the common names? Organisms can have more than one common name depending on the location(s) their habitat range. This can cause scientists problems especially if doing research. Latin is not used any longer in conversation and so it does not change. Common names can be misleading. Example: sea horse is a fish, not a horse! 9

10 *Linneaen system of classification has seven levels or taxa. Go from the most general to the most specific: Kingdom, phylum, class, order, family, genus, species. 10

11 Organisms are ranked in groups that range from having very broad characteristics to very specific ones. The broader the group, the more general its characteristics, the more species it contains. The more characteristics two organisms share, the more closely related they are. 11

12 Groups or Taxa of varying size. Domain one or more kingdoms Kingdom currently six kingdoms Phylum Class Order taxon of similar families Family consists of a group of similar genus Ex: lynx, bobcat, lions, domestic cats Genus groups of similar species that have similar features and are closely related. Species smallest group, organisms that look alike and successfully interbreed. 12

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14 Limitations: His system was created Before technology allowed us to study organisms at the molecular level focuses only on the physical similarities (wings) TODAY scientists use genetic research to help classify living things. Example: Giant Panda and the raccoon have similar ears and snouts and so they were placed in the same family in the Linnaean system. BUT molecular biology have found that the Giant Panda is more closely related to the Bears AND the red panda is more closely related to the raccoon than to the giant panda! 14

15 Classifying Organisms Today To understand underlying evolutionary relationships scientists look at the following: External features/structures Internal structures Geographical distribution Genetic makeup 15

16 Why is it important to classify organisms? To be able to study relationships among living and extinct species Useful to anyone working in agriculture, forestry, and medicine to be able to quickly identify species. Examples: knowing what a child ate, poison control center Discovery of new sources of lumber, medicines, and energy comes from knowing what we already have and linking new items to existing ones. 16

17 Grouping Organisms We can identify all kinds of organisms in the field or lab by using a useful tool called a dichotomous key. These help us to identify a specific species based on characteristics that are both unique and shared between different species. 17

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