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Powerpoint of evolution


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EVOLUTION = CHANGE Example of Evolution: Industrial Melanism

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Organisms best suited for the environment survive and reproduce. Offspring have traits similar to their parents.

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A Trinidad tree mantid that mimics dead leaves A flower mantid in Malaysia A leaf mantid in Costa Rica Figure 13.1 Organisms are adapted to their environment!

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For a long time, it was believed that organisms did not change or adapt. Mid 1700’s Fossil studies showed changes in species over time Accepted explanation was Lamarkism : inheritance of acquired characteristics

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February 12, 1809 Charles Darwin & Abraham Lincoln were born. As a boy, Darwin loved nature His father was a physician and insisted Charles attend medical school. Darwin left medical school and began studying theology. December 1831 After he received his degree, Darwin was offered a position as a naturalist on Board the HMS Beagle Video: Galápagos Islands Overview

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Darwin in 1840 Galápagos Islands North America South America PACIFIC OCEAN PACIFIC OCEAN ATLANTIC OCEAN Pinta 40 miles 40 km 0 Florenza 0 Fernandina Marchena Genovesa Equator Santiago Daphne Islands Pinzón Española Isabela Santa Cruz Santa Fe San Cristobal Great Britain Cape of Good Hope Europe Africa Cape Horn Tierra del Fuego Equator Asia HMS Beagle Australia Tasmania New Zealand Andes Figure 13.3 The 5 year voyage of the HMS Beagle

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On this voyage : Darwin collected thousands of specimens and observed various adaptations in organisms Observations that Darwin made while visiting the Galapagos Islands helped develop his understanding of nature .

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Galápagos Islands PACIFIC OCEAN Pinta 40 miles 40 km 0 Florenza 0 Fernandina Marchena Genovesa Equator Santiago Daphne Islands Pinzón Española Isabela Santa Cruz Santa Fe San Cristobal Figure 13.3c

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The turtles on each island were different… Why? Neck length based on vegetation available.

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(a) The large ground finch (b) The small tree finch (c) The woodpecker finch Figure 13.11 The finches had different beak structures as well as different feeding habits.

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Darwin made two key observations: Overproduction: All species tend to produce excessive numbers of offspring –this leads to struggle for existence Variation: Organisms vary, and much of this variation is heritable From these observations, Darwin challenged the idea of Lamarkism with his ideas of adaptation thru natural selection.

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Darwin’s Idea of Natural Selection: Organisms produce too many offspring. Offspring have different traits, many of which are inherited. There is competition for survival Those that are not adapted, die. Those that are best adapted, survive and reproduce Offspring have traits similar to parents

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Examples of natural selection include: Pesticide-resistant insects Antibiotic-resistant bacteria Drug-resistant strains of HIV

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Chromosome with gene conferring resistance to pesticide Insecticide application Figure 13.14-1

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Chromosome with gene conferring resistance to pesticide Insecticide application Figure 13.14-2

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Chromosome with gene conferring resistance to pesticide Reproduction Survivors Insecticide application Figure 13.14-3

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1809 Lamarck publishes his theory of evolution. 1830 Lyell publishes Principles of Geology . 1837 Darwin begins analyzing his specimens and writing his notebooks on the origin of species. 1844 Darwin writes his essay on the origin of species. 1865 Mendel publishes papers on genetics. 1858 Wallace sends an account of his theory to Darwin. 1859 Darwin publishes The Origin of Species . 1809 Charles Darwin is born. 1831–36 Darwin travels around the world on the HMS Beagle . Green sea turtle in the Galápagos Islands 1800 1870 Figure 13.2

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Microevolution : the change in a population POPULATION same species same place same time The smallest unit that can evolve Gene Pool: total collection of alleles in a population at any one time

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How can we tell if a population is evolving? A non-evolving population is at genetic equilibrium , in which the population gene pool remains constant over time. A change in the gene pool shows evolution. Evolution = Change

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Change is caused by: Mutations: changes in the DNA Meiosis: shuffling of alleles Natural Selection: adaptation to the environment Genetic drift Gene flow

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Genetic drift is: A change in the gene pool of a small population Due to chance Animation: Causes of Evolutionary Change

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RR rr Rr RR RR RR Rr RR Rr Rr Generation 1 p (frequency of R )  0.7 q (frequency of r )  0.3 Figure 13.22-1

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Only 5 of 10 plants leave offspring RR rr Rr RR RR RR RR Rr RR Rr Rr rr RR Rr rr RR Rr Rr Rr rr Generation 1 p (frequency of R )  0.7 q (frequency of r )  0.3 Generation 2 p  0.5 q  0.5 Figure 13.22-2

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Only 5 of 10 plants leave offspring RR rr Rr RR RR RR RR Rr RR Rr Rr Only 2 of 10 plants leave offspring RR rr RR Rr rr RR Rr Rr Rr rr RR RR RR RR RR RR RR RR RR Generation 1 p (frequency of R )  0.7 q (frequency of r )  0.3 Generation 2 p  0.5 q  0.5 Generation 3 p  1.0 q  0.0 Figure 13.22-3

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Bottleneck effect : Type of genetic drift Results from a drastic reduction in population size usually reduces genetic variation because at least some alleles are likely to be lost from the gene pool. Cheetahs appear to have experienced at least two genetic bottlenecks in the past 10,000 years.

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Original population Figure 13.23-1

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Original population Bottlenecking event Figure 13.23-2

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Original population Bottlenecking event Surviving population Figure 13.23-3

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Founder effect Type of genetic drift a few individuals colonize an isolated habitat explains the relatively high frequency of certain inherited disorders among some small human populations.

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Gene flow: Is genetic exchange with another population Tends to reduce genetic differences between populations

Natural selection promotes adaptation:

Natural selection promotes adaptation Directional selection: Selects in favor of some extreme phenotype Disruptive selection balance between two or more contrasting phenotypic forms in a population. Stabilizing selection : Favors intermediate phenotypes Is the most common

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Original population Evolved population Phenotypes (fur color) Frequency of individuals Original population (a) Directional selection (b) Disruptive selection (c) Stabilizing selection Figure 13.28

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Macroevolution: Encompasses the major biological changes evident in the fossil record Includes the formation of new species Speciation: Non-Branching Branching

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Non-Branching Branching

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The biological species concept defines a species as A group of populations members have the potential to interbreed produce fertile offspring” There are Reproductive Barriers between Species

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INDIVIDUALS OF DIFFERENT SPECIES MATING ATTEMPT Temporal isolation Habitat isolation Behavioral isolation Mechanical isolation Gametic isolation Prezygotic Barriers —prevent mating Figure 14.3a

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Temporal Isolation Skunk species that mate at different times Figure 14.4a

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Habitat Isolation Garter snake species from different habitats Figure 14.4b

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Mating ritual of blue-footed boobies Behavioral Isolation Figure 14.4c

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Mechanical Isolation Snail species whose genital openings cannot align Figure 14.4d

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Sea urchin species whose gametes cannot fuse Gametic Isolation Figure 14.4e

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VIABLE, FERTILE OFFSPRING Hybrid breakdown FERTILIZATION (ZYGOTE FORMS) INDIVIDUALS OF DIFFERENT SPECIES Reduced hybrid fertility Reduced hybrid viability Postzygotic Barriers: Altered offspring Figure 14.3b

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Frail hybrid salamander offspring Reduced Hybrid Viability Figure 14.5a

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Reduced Hybrid Fertility Mule (sterile hybrid of horse and donkey) Donkey Mule Horse Figure 14.5b

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Hybrid Breakdown Sterile next-generation rice hybrid Figure 14.5c

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Allopatric speciation: population is severed from other populations of the parent species. due to geographic isolation

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