Chapter 15 EVOLUTION

chapter 15.1 Evolution – change over time -- facts, observations, & hypotheses about the history of life

chapter 15.1 Charles Darwin – sailed on the Beagle around the world naturalist who studied plant and animal life -- noticed life’s great diversity -- wondered how it happened -- collected fossils, saw great fossil diversity -- noticed plants & animals were well adapted for survival

chapter 15.1

Beagle – traveled around the world…

chapter 15.1 Darwin’s trip – observed land tortoises & marine iguanas -- saw great variety in birds -- noticed that geographical isolation led to changes in members of the same species -- his ideas were radical for the time

chapter 15.1 Many people of the time thought that the Earth was only a few 1000 years old; did not think that any creatures had ever changed

chapter 15.2 Naturalist – had once enrolled in medical school (against his wishes) and when offered a place on the HMS Beagle he took it Well-read – studied the works of Lyell, Malthus, and Wallace Hutton & Lyell - described processes that shaped the Earth’s surface and must have happened long ago

Chapter 15.2 Lamarck – proposed that by selective use or disuse of organs, organisms acquired or lost certain traits  Tendency toward perfection – all organisms are changing to help them live more successfully  Use and disuse – organisms can alter the size or shape of particular organs by using their bodies in new ways  Inheritance of acquired traits – altered bodies could be passed on to offspring

Chapter 15.2 What’s wrong with Lamarck’s theory?  Didn’t understand genetics  Didn’t know that organism’s behavior has no effect on its heritable characteristics Malthus – economist  Noted that babies were being born faster than people were dying  He reasoned that the human population could grown exponentially and result in insufficient food and living space

Chapter 15.3 Artificial selection  Darwin noticed the great variation among species  Nature provides the variation and humans selected those variations that were useful

chapter 15.3 Darwin’s solutions – THE THEORY OF EVOLUTION AND NATURAL SELECTION  Found that the Galapagos Islands had very similar species on different islands that had different characteristics  Saw different tortoises, iguanas & finches on different islands and different from mainland  Darwin explained his view in a book – The Origin of Species by Natural Selection (published in 1859)

chapter 15.3 EVOLUTION – genetic change or ‘descent with modification’ occurs over time

Chapter 15.3  STRUGGLE FOR EXISTENCE  Darwin was convinced that there was a force in nature like artificial selection used by humans  Observed competition for food, living space and other necessities  Some prey are faster than others, better camouflaged – they catch more prey than others

chapter 15.3 SURVIVAL OF THE FITTEST – Darwin said that all organisms differ slightly; those that happen to be most suited to the environment will survive and reproduce!

Chapter 15.3 FITNESS  Ability of an individual to survive and reproduce ADAPTATION  Fitness is the result of adaptations  Adaptations are any individual characteristic that increases an organism’s chance of survival

What is the purpose of the adaptation in this animal?

What would happen? Suppose a small group of humans are rocketed at warp speed to Planet X. Planet X has no ozone layer to protect its surface from cancer-causing radiation. Native plants and animals have evolved to live safely there. Below the surface, the planet has a network of underground tunnels, just a meter in diameter, that are inhabited by carnivorous predators.

What would the humans look and act like after evolving for 100,000 years on Planet X?

chapter 15.3 COMMON DESCENT – the idea that all living things share common ancestors  Darwin proposed that over time, natural selection produces organisms that have different structures, occupy different niches and habitats  As a result, modern species would look different from their ancestors

chapter 15.3 NATURAL SELECTION – mechanism of evolution  When individuals vary in one or more traits (variation), there may be slight differences in the ability to survive and reproduce

chapter 15.3 Natural selection depended on mutations to happen and be beneficial depending on the circumstances and the environment!

chapter 15.3 EVIDENCE OF EVOLUTION FOSSIL RECORD –  Fossils form when an organism becomes buried in mud, volcanic ash, or sediments  Over time the organic remains become replaced with inorganic minerals

chapter 15.3 Darwin found fossil evidence that did not fit idea of no change

Chapter 15.3 GEOGRAPHIC DISTRIBUTION OF LIVING SPECIES  Species of finches found in Galapagos by Darwin demonstrate adaptations that caused evolution of one species into several = adaptive radiation

chapter 15.3 EVIDENCE FOR CHANGE OVER TIME:  HOMOLOGOUS STRUCTURES – similar structures that develop from similar tissue in embryological development

chapter 15.3 Similar in various species – provides strong evidence that all four-limbed vertebrates have descended, with modification, from common ancestors

chapter 15.3 VESTIGIAL ORGANS – organs that seem to have no function or purpose  Unable to explain why they are there  Examples: human appendix, pelvic bones of a whale, dewclaw in dogs

Chapter 15.3 EMBRYOLOGY  Many embryos share similar characterisitics during certain stages

chapter 15.3

THE THEORY OF EVOLUTION  GENETIC VARIATION AMONG THE SPECIES  OVERPRODUCTION  STRUGGLE FOR EXISTENCE  DIFFERENTIAL SURVIVAL AND REPRODUCTION

CHAPTER 15.3 NATURAL SELECTION  STRUGGLE FOR EXISTENCE  SURVIVAL OF THE FITTEST  DESCENT WITH MODIFICATION

chapter 15.3 Why study evolution?  Evolution is the unifying link of all living things  It is still being tested and revised  Evolution is change and change is a SLOW but constant part of biology

chapter 15.3 EXAMPLES OF QUICK EVOLUTION  Peppered Moth – Industrial melanism

chapter 15.3 RESISTANCE OF BACTERIA TO ANTIBIOTICS  Antibiotics easily wipe out most bacteria  However, if one cell is resistant to antibiotics due to natural variation and  SURVIVES AND REPRODUCES  A billion resistant bacteria will be produced by that one survivor in 10 hours!!!!!!!!!!!!