EVOLUTION  Evolution – Change in a kind of organism over time

EVIDENCE OF EVOLUTION

EVIDENCE FROM FOSSILS  Fossils are traces of once living organisms found most commonly in sedimentary rock.  Sometimes the fossil can be from hard parts of an organism including shells, bones, teeth and woody stems.  Fossils can be trapped in hardened resin (like insects) or frozen in Arctic ice (like a woolly mammoth) with skin, bones and muscle perfectly preserved.

EVIDENCE FROM FOSSILS (continued)  Fossils are not always body parts:  Example – Imprint – a film of carbon remains after all other parts have decayed.  Mold – when an impression of the shape or track of an organism has survived.  Cast – forms when sediments fill in the cavity left by a mold fossil.

EVIDENCE FROM LIVING ORGANISMS  Common ancestry – deer and elk – both are possibly from a now extinct Irish Elk  Homologous structures – parts that have similar structures but different functions  Vestigial Organs – seemingly functionless parts.  Examples: – tailbone and appendix in humans  some species of snakes have tiny pelvic bones (Anaconda in S America)  small limb bones (boa and python)  some cave dwelling salamanders have eyes even though members of the same species are blind.

EVIDENCE OF EVOLUTION FROM LIVING ORGANISMS (continued)  Embryological Development – Embryos of certain species develop almost identically.  DNA analysis  Biochemistry – example – the metabolism of different organisms is based on the same complex biochemical compounds.

EVIDENCE OF EVOLUTION FROM LIVING ORGANISMS (continued)  Geography *Geographic isolation of a species occurs when a physical barrier, such as a mountain range, stops members of two populations of a species from coming into contact with each other. *Geographic isolation of a species occurs when a physical barrier, such as a mountain range, stops members of two populations of a species from coming into contact with each other. *Interbreeding between the two populations is not possible. *Interbreeding between the two populations is not possible. *Different environmental factors may favor one adaptation over the other in the two groups. In time the populations may become different enough that they can no longer interbreed. (Reproductive isolation has taken place.) *Different environmental factors may favor one adaptation over the other in the two groups. In time the populations may become different enough that they can no longer interbreed. (Reproductive isolation has taken place.)  Antibiotic and Pesticide resistance – explain

EVIDENCE OF EVOLUTION FROM LIVING ORGANISMS (continued)  Viral evolution – explain  Over the years, breeders have used artifical selection (selective breeding) to produce plants and animals that are much more suited to human needs. These animals are often dramatically different in appearance from their original parent stock.

MASS EXTINCTION  Mass Extinction is the sudden disappearance of many species.  It is often followed by the rapid evolution of many new species known as adaptive radiation.  They fill in the “niche” left by the mass extinction  Example – large mammals filled in the “niche” left by the extinction of dinosaurs

MASS EXTINCTION TIME LINE “THE BIG 5”  Five main extinction events have been recognized, these are known as the BIG 5.  Number 1  The late Ordovician event 438 million years ago, when 100 families went extinct  Caused by a drop in sea levels as glaciers formed, then by rising sea levels as glaciers melted.  (The toll: 25 percent of marine families and 60 percent of marine genera.)

THE BIG 5 (CONTINUED)  NUMBER 2  Late Devonian 360 million years ago, when 30% of families went extinct  Cause unknown  (Killed 22 percent of marine families and 57 percent of marine genera.)

THE BIG 5 (CONTINUED)  NUMBER 3  End Permian-Triassic extinction million years ago, the biggest extinction of all time when over 50% of all families were lost.  There are many ideas as to what caused the extinction  The Permian-Triassic catastrophe was Earths worst mass extinction, killing 95 percent of all species.  (53 percent of marine families, 84 percent of marine genera and an estimated 70 percent of land species such as plants, insects and vertebrate animals. )

THE BIG 5 (CONTINUED)  NUMBER 4  Late Triassic 199 million to 214 million years ago 35% of families died out  most likely caused by massive floods of lava erupting from the central Atlantic magmatic province -- an event that triggered the opening of the Atlantic Ocean.  The volcanism may have led to deadly global warming. Rocks from the eruptions now are found in the eastern United States, eastern Brazil, North Africa and Spain.  (The death toll: 22 percent of marine families, 52 percent of marine genera. Vertebrate deaths are unclear.)

THE BIG 5 (CONTINUED)  NUMBER 5  The Cretaceous Tertiary (K-T) 65 Million years ago, which ended the reign of the dinosaurs  probably caused or aggravated by impact of several-mile- wide asteroid that created the Chicxulub crater now hidden on the Yucatan Peninsula and beneath the Gulf of Mexico.  Some argue for other causes, including gradual climate change or flood-like volcanic eruptions of basalt lava from India’s Deccan Traps.  Others believe that diseases brought from dinosaurs as they migrated across the land bridges that were present contributed to the destruction.  (The extinction killed 16 percent of marine families, 47 percent of marine genera (the classification above species) and 18 percent of land vertebrate families, including the dinosaurs.)

CLADOGRAMS  A CLADOGRAM IS USED IN CLADISTIC TAXONOMY  SHOWS RELATIONSHIPS OF ORGANISMS BASED ON SHARED CHARACTERISTICS  USED TO ESTABLISH EVOLUTIONARY RELATIONSHIPS  TO INTERPRET A CLADOGRAM, BEGIN AT THE BOTTOM AND MOVE UP

Cladogram  Diagram showing how organisms are related based on shared, derived characteristics such as feathers, hair, or scales

Primate Cladogram

Dating of Fossils  Relative Dating – A method of determining the age of a fossil by comparing them to other fossils in different layers of rock.  Radioactive Dating – a method of determining the age of an object by measuring the amount of a specific radioactive isotope it contains.

BIOLOGICAL EVOLUTION  Biological evolution is a change in the allele frequency of a species or a population over time.