Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings CHAPTER 7: The Evolution of Living Things

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Section 7.1 Change Over Time

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Adaptation A characteristic that helps an organism survive and reproduce in their environment (may be physical or behavioral)

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Species Group of individuals that can mate (reproduce) only among themselves to produce offspring Groups of individuals of same species living in same place make up a population

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Species Species evolve over time by passing on genetic info Individuals in a population do not evolve – species as a whole does Either survive the conditions they encounter or they will die Cannot change due to pressure put on them by the environment

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Species When born possess genetic traits that determine if they can survive and reproduce because it had useful traits (over time more and more useful traits are passed on) Useless traits are also passed but not possessed by all individuals since not “selected” for

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Evolution Populations gradually changing over time – thus new species are formed. New species descend from older ones

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Evolution Misconceptions Man did not come from monkey - we share a common ancestor A fin will not turn into an arm but a will see a fin turn into a better fin over time (ie. a structure will become more useful over time)

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Fossils Remains, imprints, or traces of once living organisms (usually preserved in rock) that tell us when, where, and how these organisms lived

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Fossils Can be complete organisms or parts of organisms or just a set of footprints Usually form when a dead organism is covered by a layer of sediment; minerals replace organism with stone

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Timeline of life Organizes fossils by their estimated ages & physical similarities Examine fossil record to figure out relationships between extinct and living organisms. The Fossil Record

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The geologic time scale Table 14.1

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Skeletal Structures Structure and order of bones of the human arm are similar to those front limbs of cats, bats, and whales (limbs are different sizes because they perform different functions) Suggests that all these organisms shared a common ancestor at some point in time.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure Human Cat WhaleBat Homologous Structures –Same bones in each organism even though they perform different functions

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings DNA Species that have similar traits evolved from a common ancestor and therefore will also have similar DNA. Species that share a more common ancestor have fewer amino acid differences

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Section 7.2 How Does Evolution Happen?

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Darwin –Charles Darwin – naturalist (studied nature). –Explained how evolution happens. –Hypothesized that the finches (over many generations) may have adapted to diff. ways of life (finding food, space to live) on the islands.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –Collected thousands of specimens –Observed various adaptations in organisms The Voyage of the Beagle Figure 13.3 North America Great Britain Europe PACIFIC OCEAN ATLANTIC OCEAN Galápagos Islands South America Africa Equator Australia Andes Cape Horn Tierra del Fuego Cape of Good Hope Tasmania New Zealand

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –Studied finches in the Galapagos Islands. –Discovered that finches differed on each island (they seemed similar but yet had so many diff. adaptations). Darwin Figure (a) Large ground finch(b) Small tree finch(c) Woodpecker finch

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Selective Breeding Human practice of breeding animals/plants that have certain desired characteristics (genetic traits). Ex. People breed dogs with good hunting skills or horse with great speed.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Population Humans have potential to reproduce rapidly – food supplies cannot support an unlimited population. Human populations are limited by choices we make or by starvation and disease.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Population Darwin realized any species can produce many offspring and that these populations were limited by starvation, disease, predation, competition. (only limited # of individuals survive to reproduce). Thus offspring inherit traits that help them survive in their environment.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Natural Selection  Process by which individuals better adapted to their environment survive & reproduce more than less well adapted individuals do (some genes make an organism more likely to survive to reproduce).  Individuals with certain heritable (favorable) traits leave more offspring than others  Natural selection explains how a population changes in response to its environment because these favorable characteristics will increase in the population.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Section 7.3 Natural Selection in Action

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Examples of natural selection include Natural Selection in Action –Changes in a population sometimes observed when new force affects survival of individuals – ex. Hunting elephants (tusks vs. tuskless) –Resistance = some insects and bacteria are now resistant to chemicals/drugs that at one time killed them. –Insects can become resistant because have short generation times (period between birth of one generation & birth of next generation). –Finding a mate is part of struggle to reproduce (competition occurs)

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Examples of Evolution in Nature Industrial Melanism –Peppered months (white & blends in on birch tree) but pollution lead to dark moths begin more common in industrial areas (moth adapted to environment) Finch Beaks –Birds evolved in diff. ways to adapt to food sources

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Speciation Speciation = formation of new species as result of evolution. 1. Separation – part of population becomes separated from original population 2. Adaptation – over time the two populations adapt to their diff. environments and evolve diff. traits 3. Division - can no longer reproduce w/each other and are not same species anymore

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings In branching speciation, one or more new species branch from a parent species that may continue to exist Figure 14.2b (b)Branching evolution

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Section 8.3 Humans & Other Primates

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Primates are a group of mammals that include humans, apes, monkeys, and lemurs. Primate evolution –Helps explain human origins –Humans and apes have shared a common ancestry about 5–7 million years ago –“Lucy” best preserved skeleton of prehuman hominid (3 mya) The Evolution of Primates

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure Old World monkey Gibbon Orangutan Gorilla Human Chimpanzee

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Primate characteristics include –Limber shoulder joints –Eyes in front of the face –Excellent eye-hand coordination –Extensive parental care –Opposable thumbs Figure 17.39

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure Chimpanzee fetus Chimpanzee adult Human fetus Human adult

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Ape vs. Human Skeleton Ape –“C” shape spine, arms longer than legs, narrow pelvis, smaller brain, quadraped Human –“S” shape spine, arms shorter than legs, bowl shaped pelvis, large brain, biped

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Humans are Homo sapiens (means wise man) Homo sapiens are only 34,000 years old Can walk upright Modern Humans