GCO: How are living things organized into groups for ease of study – SCO: Describe peer review and explain how classification systems developed as new evidence concerning living things emerged (114-5, 115-7, 116-2) – SCO: Identify questions, limitations, and alternatives inherent in a classification system (214-2, 214-7, 212-1)

Where else can creating groupings/categories be of use to us in society, worldwide?

Taxonomy: The science of classifying living things. Unity: Similar characteristics among organisms which group them together (how similar organisms are). Diversity: Different aspects between organisms that place them into different groups (how organisms are different). Species: A group of organisms, alike in many ways, that can interbreed under natural conditions to produce fertile offspring. Genus: A group of similar species. Phylogeny: The evolutionary history of a species.

Living things MUST: 1)grow and develop 2)respire 3)have cells 4)use energy 5)respond to stimuli 6)generate heat 7)reproduce

Helps organize information about organisms Makes it easier to identify both known, and unknown organisms Shows relationships among organisms

Think of scientists as reverse engineers – Interested in the smaller, component parts and how they form the larger organism Started classifying plants first, which led into the classification of animals Began classifying according to superficial divisions (Cesalpino – differentia) – misleading?

Aristotle – Greek philosopher and naturalist – First known classification system (2000+ years ago) animal or plant where they lived (terrestrial (land), aquatic (water), aerial (air), etc.) arranged hierarchically by complexity – scala naturae (ladder of nature) not perfect (bats, birds, mosquitoes – can fly)

John Ray – 17 th century English botanist – Identified more than 18,000 plants – led to modern plant taxonomy – Used term species in classification species: group of organisms that looked alike and could reproduce among themselves.

Carolus Linnaeus – 18 th century Swedish botanist – New classification system based physical/structural characteristics more features in common, closer in relation – “Father of Modern Taxonomy” binomial nomenclature (8 names before genus prior) – Utility of Reproductive/Sexual Systems Less subject to environmental selection pressures – Species “blend” together Not intended, but influential for Darwin and Wallace – Ladder of species (separate rungs)

Focus on physiology, anatomy, and behaviour (Buffon) – downplayed the importance of taxonomy Taxonomy became more of a continuum (simple to complex) Correlation of characters (Cuvier) Affinities – characters exhibited at any level (similarities in groups – fins, hair, ability to feed young milk, etc.)

Analogous Structures – functionally similar, but made up of different constituent parts. Fossil records (limiting, but useful) Evolution (Darwin) – Sexual Selection – Theory of Natural Selection

Hierarchical system most common among scientists – graded/ranked – artificial/arbitrary/limited – imposed by humans Biochemical Similarity – blood composition, protein sequence (amino acids), etc. Genetic Similarity (how close are DNA/RNA sequences) Fossil Record (limited – extinct) Behaviour

Embryonic Development

Comparative Anatomy – homologous structures same basic pattern and same pattern of development – not necessarily same function

How did the theory of evolution influence classification? In 1859, a British Scientist names Charles Darwin explained how living things may have evolved over time. Today, Darwin’s theory of evolution is accepted by most scientists. Taxonomists started to classify living things according to their phylogeny or evolutionary history. Today, taxonomists try to develop an evolutionary tree for every species which shows the inferred relationships among different species (one common ancestor).

Linnaeus developed a naming system called binomial nomenclature. – Each organism is identified by a two part scientific name which is still used today. – The first part is the name of the genus and the second part is the name of the species. – Indicates similarities in anatomy, embryology, and evolutionary history. – Based on some characteristic (colour, habitat, etc.) Castor canadensis (beaver from Canada) – Latin names for his system as it allowed for a common language, regardless of national origin

Rules for writing the scientific name: – The first letter of the genus is always capitalized. – The first letter of the species name is never capitalized. – Both names must be underlined or italicized.

When creating groupings/categories at the beginning of the lesson, you made certain decisions based on previous knowledge and/or your own observations. Explain why you chose to divide things the way you did, and rationalize/justify why you had difficulty.

“Science is the systematic classification of experience.” – George Henry Lewes