Charles Darwin 1809 - 1882 Charles Most influential contributor - PDF document

Charles Darwin  1809 - 1882 Charles  Most influential contributor to thoughts about Darwin evolution  The Origin of Species  1859  Presented evidence for changes in species through Natural Selection 1 2 Contrast of Views Darwin’s Voyage  1831 - at age 22  5 year round-the-world voyage  H.M.S. Beagle  Ship’s naturalist  At beginning of trip  Believed species were immutable  As ship’s naturalist, he collected and examined the species that inhabited the regions the ship visited  Many collections  Fossils,coral,plants, animals 3 4 HMS Beagle 5 6 1

Galapagos Islands  Volcanic islands - 3.5 mya  Isolated, west of Ecuador  All inhabitants are descended from species that arrived on islands from elsewhere EQUATOR Galapagos Islands 7 8 Darwin’s Finches Galapagos Tortoises  13 species of finches  Share many morphological WET ISLANDS features Short neck Domed shell  Differ in several ways  Beak size  Beak shape  Food eaten  Evolved from a single species Long neck Flared shell  He attempted to correlate DRY ISLANDS variations in their traits with environmental challenges 9 10 Galapagos Iguanas Theory of Natural Selection Alfred Russel Wallace Marine Iguana Algae eater Land Iguana Terrestrial vegetation Charles Darwin 11 12 2

Darwin’s Theory Alfred Russel Wallace  1823-1913  Naturalist who arrived at the same  A population can change over time when conclusions Darwin did individuals differ in one or more heritable  Wrote to Darwin describing his views traits that are responsible for differences in  Prompted Darwin to finally the ability to survive and reproduce. present his ideas in a formal paper  Both presented papers  Linnean Society of London  July 1, 1858 13 14 “On the Origin of Species” Darwin & Wallace Proposed Two Theories  1. The living organisms we see today are all related  Basic draft finished in 1842 by descent (common ancestry)  Kept in drawer for 16 years  2. The means by which evolution occurs is a process of 'natural selection.'  Other research  organisms differ from one another  Coral reefs  i.e., there is variation  Barnacles  these differences are heritable,  i.e. passed from generation to generation many  Joint presentation of ideas at Linnean  more organisms are born than survive and reproduce Society (mortality)  therefore, any variation that makes one offspring more  Final draft published - 1859 successful than another will have a greater chance of being passed to the next generation  Immediate sensation  ("survival of the fittest") 15 16 DARWIN’S OBSERVATIONS and DEDUCTIONS DARWIN’S OBSERVATIONS and DEDUCTIONS 17 18 3

DARWIN’S OBSERVATIONS and DEDUCTIONS DARWIN’S OBSERVATIONS and DEDUCTIONS 19 20 DARWIN’S OBSERVATIONS and DEDUCTIONS DARWIN’S OBSERVATIONS and DEDUCTIONS 21 22 DARWIN’S MAIN IDEAS DARWIN’S OBSERVATIONS and DEDUCTIONS DARWIN’S OBSERVATIONS and DEDUCTIONS 23 24 4

REVIEW OF DARWIN’S POINTS 1-2 REVIEW OF DARWIN’S POINTS 3-4  Natural selection is the outcome of  Individuals of a species vary in form, differences in the survival and function, and behavior reproduction of individuals that show  Much of the variation is heritable variation in one or more traits  Can be transmitted from parents to offspring  Natural selection leads to a better fit with  Some forms of heritable traits are adaptive prevailing environmental conditions. to the prevailing environmental conditions  Adaptive forms of traits tend to become more  They improve an individuals chance of common and other forms less so surviving and reproducing  The population changes its characteristics  IT EVOLVES 25 26 NATURAL SELECTION Natural Selection  A difference in the survival and reproductive  “Those individuals that success of different phenotypes possess superior  Acts directly on phenotypes and indirectly on physical, behavioral, or other attributes are more genotypes likely to survive than  Change over Time those that are not so well  Over time, the alleles that produce the most endowed” successful phenotypes will increase in the population  Selection  Less successful alleles will become less common  Change leads to increased fitness  Artificial  Increased adaptation to environment  Natural  Survival of the fittest 27 28 Natural Selection- Put Another way THE EVOLUTIONARY VIEW  Individuals vary in some heritable traits Life’s diversity is the sum total  Some forms of heritable traits are more adaptive of variations in traits that have  A trait that gives the individual an advantage in accumulated in different lines survival or reproduction, under a given set of circumstances of descent generation after  Natural selection is differences in survival and generation, as by natural reproduction among individuals that vary in their traits selection or other processes  Adaptive forms of traits become more common of change than other forms 29 30 5