Presentation on theme: "“Survival of the Fittest”"— Presentation transcript:
1 “Survival of the Fittest” Changes through timePhotos (L to R): 1. African lion attempting to take down a cape buffalo as an example of a predator-prey relationship. The traits of those who survive long enough to reproduce are those past on to the next generation while the traits of those who do not survive are not past on. This is the basis for natural selection – or “survival of the fittest.” 2. A Colorado Potato Beetle. Populations of the potato beetle have become resistant to certain pesticides. This is an example of changes in populations occurring within our lifetime. 3. Fossil of a fish found in the Green River formation near Kemmerer, Wyoming. The fossil record provides much detail on how populations have changed over time.“Survival of the Fittest”
2 Evidence that life has changed and is now changing Images: Left to rightLayers of sedimentary rock show relative position of fossils near Lake Powell, UTTrilobite fossil from Utah Shale – Millard County, UT. Trilobites once inhabited much of Utah and are now extinct.Antibiotic resistance in bacteria is an example of change in populations observed in our lifetime. There has been much concern recently about “super bugs” such as antibiotic resistant staph infections contracted in hospitals.
3 Fossil RecordFossils are remains or traces of organisms that lived in the past.Photo: Dinosaur fossils in the Morrison Formation, Dinosaur National Monument near Vernal, UT
4 Fossil Record Fossils are usually found in sedimentary rock. Organisms are buried soon after death and the hard parts become fossilized.Photos: Dinosaur tracks at Dinosaur Discovery site, Johnson Farm, St. George, Utah, UT. Copyright Calvin Hamilton. Used with permission. Additional photos can be found at
5 Fossil RecordFossils indicate a great deal about the actual structure of the organisms and their environment.Left: Morrison Formation in Utah near Dinosaur National Park. Steeply dipping sandstone and shale beds are seen in the picture.Right: Navajo Sandstone Formation viewed from Hidden Canyon Trail, Zion National Park.
6 Types of fossils Petrified Bones Photos (Left to Right): Petrified bones from Dinosaur National Monument near Vernal; Allosaurus (“Al”) mold at the College of Eastern Utah Prehistoric Museum in Price.
7 Types of fossils Imprints Dinosaur imprints from San Rafael Swell – Buckhorn Wash near Castledale, UT
8 Types of fossils Molds/Casts Left to Right: Fossil mold found near Provo, UT; Cast Fossil of Cephalopod
9 Fossils preserved in tar, amber, or ice Types of fossilsFossils preserved in tar,amber, or iceLeft to Right: Saber-toothed cat fossil from the La Brea Tar Pits in Los Angeles; Insect preserved in amber; Remains of a man from stone age found preserved in a glacier in the Alps; Columbian Mammoth Fossil found in Huntington Canyon near Price, UT. It had been preserved in ice cold mud.
10 Relative Age of Fossils Layering of fossils:Older fossils are found in the lower levels of sediment
11 Relative Age of Fossils Layering of fossils:Newer fossils deposited on top of older fossils and sedimentSometimes flipped by earthquakes, etc.
13 Relative Age of Fossils Fossils in each layer usually of those organisms that lived at the time the layer was formed.Fossils in lower layers represent species that lived earlier than those found in the upper layers.Relative position only tells which are older and which younger.
14 Evolution of the HorseOver time (higher layers of sediment) horse fossils became largerSeparate toes became a single-toed hoofTeeth became adapted to grinding grasses
15 Radiometric DatingSome elements, such as uranium, undergo radioactive decay to produce other elements.Scientists have observed that radioactive elements (isotopes) decay at a constant rate over time
16 Radiometric DatingThe amount of radioactive elements remaining in a rock can help scientists determine how much time has elapsed since the rock was formed and cooled.Common isotopes used for long-term dating (old rocks) include uranium as it decays to lead, and potassium as it decays to argon.The carbon-14 isotope can be used for dating of more recent fossils and artifacts
17 Radiocarbon DatingCarbon-14 is a radioactive isotope found in all living organisms.It decays at a known rate.Carbon-12 does not decay.By comparing the ratio of C-12 to C-14 scientists believe they candetermine the age of a fossil
19 A timescaleBased on radiometric data, scientists have proposed a timeline for the history of the earth.Composed of four primary “eras”Archeozoic (oldest) [aka Precambrian period]PaleozoicMesozoicCenozoic (most recent)
20 Contemporary Changes Evidences we can observe within our lifetime Pesticide resistance in insectsPictures (L): Diamondback moth developed resistance to Bacillus thuringiensis (Bt). The Colorado Potato Beetle has developed resistance to certain pesticides.
21 Contemporary Changes Evidences we can observe within our lifetime Antibiotic resistant bacteriaPictures: “Superbugs” are becoming more of a concern as bacteria are found, primarily in hospitals, that are resistant to antibiotics.
22 Indirect evidencesScientists cite these indirect evidences as evidence of common ancestryHomologous structuresEmbryonic development patternsBiochemical evidenceVestigial organsThey at least demonstrate a common pattern of development
23 Parts of the body with similar structure (homologous) HumanCatWhaleBat
24 Similar patterns of embryonic development (homologous) HumanSwineReptileBirdYes, you had a tail as an embryo!
25 Homologous Development – actual photos of embryos ReptileBirdRabbitHuman
26 Biochemical similarities – DNA and Proteins The ability to analyze individual biological molecules (DNA and proteins) has provided evidence for biochemical similarities
30 Charles Darwin and Natural Selection (1859) Naturalist on the HMS Beagle
31 Charles Darwin and Natural Selection (1859) Exploration of South America (3 ½ years)Visited the Galapagos Islands
32 Darwin’s theory of Natural Selection Living things increase in number geometrically (overproduction)There is no net increase in the number of individuals over a long period of timeSpider eggs: Many more produced than will survive
33 Darwin’s theory of Natural Selection A “struggle for existence” since not all individuals can surviveNo two individuals exactly alike (variation)
34 Darwin’s theory of Natural Selection In the struggle for existence, those variations which are better adapted to their environment leave behind them proportionately more offspring than those less adapted“Survival of the Fittest”
35 A Modern PerspectiveMutation – a sudden change in the genetic material (a source of variation)Example: The DNA of one bacteria changes (becomes mutated), allowing it to become resistant to an antibiotic. It survives long enough to reproduce. Each succeeding generation has the mutated copy and is resistant to the antibiotic.
36 A Modern PerspectiveRecombination of genes within a population (sexual reproduction)Provides new combinations for natural selection to try.Shows how the percentage of a gene in a population can change.
37 A Modern PerspectiveIsolation – separation of a population from others of the same kind (species)Prevents recombination of genesSpecies become different overtimeExample: A species of primrose existed together where the Promontory Range (Northern Utah) now exists. When the range lifted up, it isolated two groups. Both became different as they adapted to the different environments on either side of the range. They have become so different they can no longer reproduce.
38 A Modern PerspectiveNatural Selection – certain traits give an adaptive advantage to organisms and they leave behind more offspringThey survive long enough to reproduce and pass on their genetic informationINDIVIDUALS DO NOT EVOLVE . . .POPULATIONS EVOLVE OVER TIME
39 SpeciesA group of individuals that LOOK similar and are capable of producing FERTILE offspring in the natural environment.
40 PopulationAll of the members of the same SPECIES that live in particular AREA at the same TIME.
41 Variation in a population Bell Curve - The distribution of traits (Average is the middle.)Mode - The number that occurs most often (High pt.)Range - The lowest number to the highest number
53 Stabilizing Selection Individuals with the AVERAGE form have the ADVANTAGEExample – lizards that are small are not fast enough to avoid predators; lizards that are large cannot hide easily from predators; those of average size are both fast enough to get away from predators and small enough to hide – giving them the selective advantage.
55 Directional Selection Individuals with one of the EXTREME forms have the ADVANTAGEExample – Peppermoth in Great Britain during the industrial revolution – “melanistic” (dark colored) moths had the selective advantage after trees where covered in coal soot. After air quality improved, the selection advantage returned to the lighter colored moths.
56 Directional Selection Peppermoth – find two moths per picture
57 As the ants dig deeper, anteaters with longer tongues have the adaptive advantage – survive to reproduce.
58 Disruptive SelectionIndividuals with either of the EXTREME forms have the ADVANTAGEExample: a shellfish living in shallow ocean water is preyed upon by a bird. Originally those with the neutral color (sand colored) had the advantage because they were camouflaged in the sand. As the birds fed on the shellfish and left their feces behind in the water, the ocean floor became white in color. Those shellfish that were sand colored are now easily found while the lighter colored shellfish are able to blend in, as are the darker colored shellfish if they are found on the darker rocks.
73 Natural Selectionan organisms’ ability to SURVIVE and pass on its GENETIC information to its offspring.
74 Selective Breeding Also known as Artificial Selection Human control over organisms passing on their genetic information.Human determination of those crops and livestock allowed to reproduceBased on desired traits
75 Selective BreedingIn what ways is selective breeding similar to natural selection?In what ways is it different?
76 Archeozoic Era Oldest known rocks and fossils Animals without backbonesJelly-fish, worms, spongesBacteria and blue-green algae
77 Paleozoic Era Estimated from 248-550 million years ago Animals: Fish, amphibians, and insectsPlants: Algae and simple plants; first conifers
78 Mesozoic Era Estimated from 65-248 million years ago Age of the DinosaursAnimals: Reptiles and birdsPlants: Conifers and first flowering plants
79 Cenozoic Era Estimated from present to 65 million years ago Age of the MammalsAnimals: Mammals and birdsPlants: Flowering plants