Ch 1.2 Course Overview

Evolution as a Unifying ThemeCh 1.2 Course OverviewIII. Evolution- the unifying theme of biologyA. Evolution is used to unify biology at different scales of size through out the history of life on Earth.1. Roughly 1.8 million of the 10 to 100 million species thought to live on Earth are identified. Thousands are discovered yearly.a. Taxonomy is the science that names and groups (classifies) species into increasingly broad categories.b. The categories, going from broadest (largest) tonarrowest (smallest) are:DomainOrder Kingdom Family Phylum Genus Species name Class speciesTaxonomy illustration

B. Organizing Diversity- Domains & Kingdoms1. Placement into a category depends on similarities in structure, function, embryo development and DNA2. A three domain, six kingdom system is currently used.3. Two domains contain only prokaryotes. (bacteria.)4. The domains are:a) Archaebacteria- bacteria adapted to extreme conditions, possibly the oldest organisms on Earthb) Eubacteria- most bacteriac) Eukarya- contains only eukaryotes; everythingother than bacteria & virusesThe Domains

4. Four kingdoms are found in Domain Eukarya. They are: a) Protista- protozoans & algae b) Fungi c) Animalia d) PlantaeThe other two kingdoms are Archaebacteria and Eubacteria- also known as Domains

The Kingdoms

C. Unity in DiversityLife is diverse, but unity can be found in all life on a cellular level.a. The structure & function of DNA is the same for all cells.b. DNA is the universal genetic language of all organismsc. Organelle structure & function is the same in eukaryotic cells.

D. Charles Darwin & the theory of Natural SelectionDarwin published On the Origin of Species by means of Natural Selection in 1859.His 2 main points werea. Species show evidence of descent with modification from common ancestorsb. Natural selection is the means by which descent with modification occurs.Fossils and other evidence of how life on Earth has changed over billions of years is used to support his theory.Darwins theory can be used to explain both the unity & diversity of life.E. Darwins ObservationsIndividuals in a population have traits that vary.Many of these traits are heritable.More offspring are produced than survive.Competition is inevitableOrganisms usually suit their environmentsDarwins InferencesThe individuals best suited to their environment will most likely survive & reproduce.Eventually, most of the population will have the helpful traits.Thus, the environment selects for the beneficial traits.Also, by selection, an ancestral species can become two or more descendant species.

Natural Selection

G. Phylogenetic treesPhylogenetic tree- a diagram used to illustrate possible evolutionary relationships between ancestor & their descendant species.

Questions:Choose a plant, fungus, or animal familiar to you and classify it from Domain to species. Use the internet to look it up. Do not use the one in the book or the notes!What are the criteria used to place organisms into groups? Name the all the domains and kingdomsWhen did Darwin publish On the Origin of Species? What were his two main premises?What 4 inferences did Darwin draw from his observations?