The Evolution of an Idea PDF

The Evolution of an Idea Charles Darwin  Changes between generations Evolutionary Adaptation: when a mutation is favoured by the environment 🡪 Mutations produce heritable changes in individuals, called derived (new) trait. 1. This trait can be harmful to the individua...

The Evolution of an Idea Charles Darwin  Changes between generations Evolutionary Adaptation: when a mutation is favoured by the environment 🡪 Mutations produce heritable changes in individuals, called derived (new) trait. 1. This trait can be harmful to the individual in a given environment leading to the loss of trait within the species population (gene pool) Trait colour cannot be recognized, so no pollination 2. This trait can be neutral to the individual in a given environment leading to a sustenance of the trait within the species population, but with low frequency (a low number has it) Infrequent pollination 3. This trait can be favourable to the individual in a given environment leading to a spreading of the trait via reproduction within the species population (high frequency) Trait colour attracts bees effectively so lots of pollination Mutations and the Environment ⚫ The impact of a mutation also depends on the environment in which it is expressed ⚫ The same mutation can be harmful in one environment, neutral in another, and beneficial in still another ⚫ Example: ⚫ A mutation in the gene that codes for one part of the hemoglobin molecule can cause considerable damage and discomfort at extremely high altitudes, but cause no problems at all at sea level. ⚫ Other mutations may not become harmful to an individual unless he or she is exposed to a toxic chemical, carcinogen, allergen, or a specific environmental agent that acts on a genetic susceptibility. ⚫ Beneficial mutations include those that have allowed our species to acquire new, adaptive structures and functions during evolutionary history (e.g. opposable thumbs, binocular vision). There would be no evolution in any species without the genetic variation produced, in part, by mutations! Adapted from: http://www.nchpeg.org/dentistry/index.php?option=com_content&view=article&id=22&Itemid=55&limitstart=3  What is Evolution? Gradual Change in the inherited traits (genes) of a population of organisms from one generation to the next  How do organisms evolve? Individual organisms DON’T evolve, populations evolve. How do populations evolve? (Hint: what did we study in the last unit?)  GENES!! Recall: DNA contains genes that carry the code responsible for building that organism in a very specific way. Genes are passed from parent to offspring. In order for evolution to occur, the change must be at the genetic level and be passed on to the next generation Darwin & Natural Selection 7  The Voyage of the H.M.S. Beagle December 27, 1831 Darwin offered position as ship’s naturalist Sailed to South America, along its coast and to Galapagos Islands off coast of Equator  The voyage that changed the face of biology… Darwin set sail on the H.M.S. Beagle (1831-1836) to survey the south seas (mainly South America and the Galapagos Islands) to collect plants and animals. Darwin’s observations of the geographical distribution of wildlife and fossils he collected on the voyage puzzled him WHY DID SOME SPECIES SURVIVE WHILE OTHERS BECAME EXTINCT? Darwin conceived his theory of natural selection in 1838 12  Copy this in your notes!! Theory of Evolution by Natural Selection Over time, the population Theory of Natural Selection changes as advantageous heritable traits become more common generation after generation Inferences Some individuals will inherit traits Individuals in a population that give them a better chance of compete for resources surviving and reproducing (survival of the fittest) Observations More offspring are produced than can Individuals in a Food and other Many variations are survive due to limited population vary resources are limited heritable resources (genetic variation) (overpopulation)  Natural selection occurs through an interaction between the environment and the genetic makeup inherent among the individual organisms making up a population. Natural selection is differential success in reproduction (unequal ability of individuals to survive and reproduce) The process of natural selection is the adaptation of populations of organisms to their environment. 1 4 Theory of Natural Selection Individuals with heritable, favorable traits results in a population that is better adapted to its current environment. Galapagos finches show diversity in bill size and shape. Each species has adapted to a specific type of food. The ground finch has a thick beak for eating seeds, while the warbler finch has a slender, pointy bill for catching insects.  Evolution of Antibiotic Resistance in Bacteria Antibiotic resistance evolves by natural selection, much as pesticide resistance evolves in insects. An antibiotic causes selection among the varying bacteria of a population, leaving those individuals that can survive the drug. While the drug kills most of the bacteria, the resistant bacteria multiply and quickly become the norm in the population rather than the exceptions http://evolution.berkeley.edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College. Helpful Terms: Adaptation: a structure, behaviour, or process that helps an organism survive in a particular environment. Mimicry: an example of a structural adaptation which helps a harmless species resemble a harmful one, or a colouration in structure. Vestigial structure: a structure or feature that has no apparent function but appears to have been from a past ancestor or an ancestral trait (evidence of evolution) How do we get variation in a species? Mutations: a change in the genetic material of an organism, which gives rise to new genes and new traits. 1 8 1 9 Orchid Mantis HAWKMOTH CATERPILLAR  BEE ORCHID Amoeba Sisters! 2 3 Practice Questions 1. According to Darwinian evolution, there must be variation and selection. In the evolution of large claws in lobsters: a. What trait(s) might have been variable? b. What factors might have resulted in members of the population being selected? 2. Speculate about why predatory cats such as lions have not evolved to be as fast as the cheetah. Hint: lions and cheetahs live in different ecological niches. 3. The elephant has evolved to be a great size, while the mouse has evolved to be relatively small. Explain how natural selection might favour a different size in each mammal species. 4. Would you consider human body hair to be a vestigial feature? Explain.2 4 If you’d like more practice… try the Natural Selection Gizmo listed under our class gizmo page 2 5