Lecture 15 Outline of Last Lecture I. Evolutionary thought has a long history II. Important definitions III. Other evidence supporting evolution IV. Hot off the press! - April 6, 2006 V. “Missing Link” between fish and amphibians VI. Other evidence supporting evolution VII.Sexual selection may produce sexual dimorphism Outline of Current Lecture I. The Origin of Species II. What is a species? III. Species Definitions IV. Maintaining Species V. MECHANISMS OF SPECIATION VI. The tempo of speciation can appear steady or jumpy VII.Complex structures VIII.History of the Universe IX.But how do we know how old things are? X. Radiometric dating XI.Continental Drift XII.Earth’s Geographical History BIOL 1543 1st EditionThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. !Edited with the trial version of Foxit Advanced PDF EditorTo remove this notice, visit:www.foxitsoftware.com/shoppingXIII.Consequences of plate tectonics XIV.Mass extinctions are followed by diversification XV.Phylogeny and Systematics XVI.Arranging Life into Kingdoms is a work in progress Current Lecture I. The Origin of Species a. This chapter links “microevolution” with “macroevolution.” b. Microevolution = Changes in a population’s gene pool over a succession of a few generations w/o changing species. c. “Mesoevolution” is a term that could mean development of a new species – speciation. d. Macroevolution = evolutionary change on a grand scale including mass extinctions. II. What is a species? a. Carolus Linnaeus, a Swedish physician and botanist, used physical characteristics (phenotypes) to distinguish species. b. He developed the binomial system (used now)(Genus species) that established the basis for taxonomy, the branch of biology concerned with naming and classifying the diverse forms of life. c. Similarities between some species and variations within a species can make defining a species difficult. III. Species Definitions a. The Biological Species Concept i. The biological species concept defines a species as a population or group of populations whose members can interbreed and produce fertile offspring. b. Other Species Concepts i. Morphological species concept (Carolus Linnaeus used)ii. Ecological species concept - define a species by their ecological niche iii.Phylogenetic species concept - define a species based on its unique genetics IV. Maintaining Species a. Reproductive barriers keep species separate i. Reproductive barriers (biological barriers) serve to isolate a species’ gene pool and prevent interbreeding. They are categorized as prezygotic or postzygotic. ii. Know table 14.3 b. Prezygotic Barriers i. Prezygotic barriers prevent mating or fertilization between species. They include: 1. temporal isolation - timing is different 2. Habitat 3. behavioral isolation - no sexual attraction 4. mechanical isolation - physically doesn’t work 5. Gametic - the sperm and egg don’t recognize each otherc. Postzygotic Barriers i. Postzygotic barriers operate after hybrid zygotes are formed. These include: 1. hybrid inviability - fails to develop 2. hybrid sterility 3. hybrid breakdown - hybrids offspring is weak V. MECHANISMS OF SPECIATION a. Geographic isolation can lead to speciation i. In allopatric speciation, a population is geographically divided, and new species often evolve. b. New species can also arise within the same geographic area as the parent species i. In sympatric speciation, new species may arise without geographic isolation ii. Many plant species have evolved by polyploidy: multiplication of the chromosome number due to errors in cell division VI.The tempo of speciation can appear steady or jumpy a. Gradualism: species evolve by the gradual accumulation of changes brought about by natural selection b. Punctuated equilibrium: species change the most as they arise from an ancestral species and then change relatively little for the rest of their existence VII.Complex structures a. 14.11 Evolutionary novelties may arise in several ways i. Many complex structures evolve in many stages from simpler versions having the same basic functionb. Has Mickey evolved? c. Evolutionary trendsies that have evolved have died out, and most evolutionary trees have had lots of unsuccessful branches. d. Evolution does not fashion “perfect” organisms i. Natural selection can only operate on existing variations - it does not create new ones. ii. Chance is a major part, and sometimes adaptations are compromises. VIII.History of the Universe a. If the Universe (13.7 billion years) were reduced to one Earth-year… i. 1 January: The Big Bang ii. 7 February: The Milky Way is “born” iii.14 August: The Earth is “born” iv. 4 September: First life on the Earth v. 15 December: The Cambrian Explosion vi.25 December: The dinosaurs appear vii.30 December: Extinction of the dinosaurs viii.31 December: ix. 7:00:00 pm: First hominids (human-like) © Copyright Disney Enterprise, Inc.x. 11:58:00 pm: First humans xi.11:59:30 pm: The “Age of Agriculture” xii.11:59:47 pm: The pyramids were built xiii.11:59:58 pm: Jesus Christ is born xiv.11:59:59 pm: Galileo is born xv.12 midnight - today IX.But how do we know how old things are? a. There are methods for aging rocks and fossils in geologic time b. Radiometric dating measures the decay of radioactive isotopes (see section 2.4). We can gauge the actual ages of fossils and the rocks in which they are found, for example, “carbon-dating.” X. Radiometric dating a. Isotopes of other elements are used when we need to go back even further. XI.Continental Drifta. The slow, incessant movement of Earth’s crustal plates on the hot mantle has affected the distribution of animals (and their fossils). XII.Earth’s Geographical History Edge of one plate being pushed over edge of!neighboring plate (zones of violent geologic events)Antarctic PlateAustralian!PlateSplit!Indian!PlateEurasian PlateNorth!American!PlateSouth!American!PlateNazca!PlatePacific!PlateArabian!PlateAfrican!PlateXIII.Consequences of plate tectonics a. plate tectonics- refers to forces involved in the movement of the earth’s plates b. New Madrid fault line in Arkansas i. 3-5 major fault segments that lie on top of each other c. The earth quakes in 1811-1812 in Arkansas were the strongest earth quakes to occur in the US XIV.Mass extinctions are followed by