Taxonomy & Evolutionary History I. Taxonomic Concepts II. Taxonomic Principles III. Time Scale IV. Rate of Evolutionary Change

I. Taxonomic Concepts A. Taxonomy – scientific system for classification. Uses a set of rules to determine relationships among items (organisms?) in a set. B. Today, still based on Linnaeus’ seven level system: Kingdom, Phylum, Class, Order, Family, Genus, and Species. C. Remember as King Phillip Crossed Over For Grape Soda D. All organisms are referred to by their genus & species (binomial nomenclature).

II. Taxonomic Principles A. Structures that are shared through descent from a common ancestor are called homologies. B. Homoplasy is the process by which similarities can develop in different groups of organisms. Leads to analogous structures.

II. Taxonomic Principles C. Structures in organisms that are used for the same function, but have developed independently and are not the result of common descent, are called analogies. D. Analogies are often the result of convergent evolution.

II. Taxonomic Principles E. Cladistic Taxonomy An approach to taxonomy that groups species according to shared derived characteristics. 1. Traits that reflecting the ancestral condition of an organism are primitive. 2. Traits shared by all members of a group, but not present before the group's appearance, are said to be shared derived characteristics (e.g nails in primates).

II. Taxonomic Principles E. Cladistic Taxonomy 3. Related groups are thus in the same clade, or branch/level (genus, family, or whatever) 4. At the finest levels, determining where one species starts or stops, however, is sometimes a problem.

II. Taxonomic Principles F. Speciation 1. Groups of organisms capable of breeding to create fertile offspring that COULD normally be expected to contact one another. 2. Species are reproductively isolated from one another: i. Biological – physical or genetic limitations ii. Geographic – separation of the organisms on the landscape iii. Behavioral – social separation of organisms (e.g. nocturnal/diurnal)

III. Time Scale: Geological Eras A. Paleozoic The first vertebrates appeared 500 mya The first vertebrates appeared 500 mya B. Mesozoic Reptiles were dominant land vertebrates. Reptiles were dominant land vertebrates. Placental mammals appeared 70 mya Placental mammals appeared 70 mya C. Cenozoic Divided into two periods: Tertiary and Quaternary and 7 epochs. Divided into two periods: Tertiary and Quaternary and 7 epochs.

III. Time Scale: Cenozoic Epochs Draw and leave space to fill this chart: EpochTimePrimates Paleocene65 mya Eocene55 mya Oligocene34 mya Miocene23 mya Pliocene 5 mya Pleistocene1.8 mya Holocene 0.01 mya

III. Time Scale: Mammal Evolution A. The Cenozoic era is known as the Age of Mammals. B. After dinosaurs became extinct at 65 mya, mammals underwent adaptive radiation, resulting in rapid expansion and diversification. C. One advantage was the larger neocortex, which controls higher brain functions, comprised the majority of brain volume in mammals resulting in greater ability to learn.

III. Time Scale: Mammal Evolution D. Another was the variety of diet mammals were capable of, due to their digestive and dental differentiation (heterodont – having many types of teeth) E. Yet another was mammals’ endothermy, or ability to easily self-regulate their body temperature F. Still another was mammals’ emergence of marsupial and later placental birthing – keeping the developing embryo inside the mother for protection and greater development

IV. Rate of Evolution A. Punctuated Equilibrium – Long periods of no change punctuated by rapid evolution and speciation right) – S. Gould and N. Eldredge – Explains gaps in record B. Phyletic Gradualism Darwin’s idea of slow gradual change leading to eventual speciation