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change that occurs over time it is NOT how life originated on Earth it is a scientific theory, which means it is supported by scientific evidence MICROEVOLUTION refers to smaller scale evolutionary changes within a species; can be seen in a lifetime ◦ Example: bacteria changes MACROEVOLUTION refers to large scale evolutionary changes; cannot be seen in a lifetime ◦ Example: formation of new species Divergent Evolution Convergent Evolution Coevolution Divergent Evolution related species becoming more dissimilar Spontaneous Generation* (life can arise from nonliving things) was being replaced by Biogenesis (life arising from life). ◦ *Disproved by Redi (meat experiment) and Pasteur (broth experiment) Earth was… a few thousand years old populated by unchanging life forms - made during a single week in which the creator also formed the entire universe Neither the planet nor its inhabitants had changed since creation Rocks and major geological features were produced suddenly by catastrophic events – floods, earthquakes, … Darwin - NOT the first to suggest evolution several Greek philosophers (Plato & Aristotle) believed in a “gradual evolution of life” Linnaeus ◦ Father of Taxonomy (the science of classification) grouped similar species into categories ◦ devised system of binomial nomenclature Cuvier - developed the science of Paleontology He said… each layer (stratum) of rock has unique fossil species the deeper the stratum, the more different the fossils are from modern life due to relative age Hutton and Lyell - said that the Earth is millions of years old ◦ changes in Earth result over a long period of time ◦ geological processes continue to “shape” the Earth today Darwin was especially influenced by the work of Hutton and Lyell because… He reasoned that if Earth could change, so could its living inhabitants Lamarck ◦ Wasthe first to suggest how evolution might occur Proposed 2 main ideas: 1. Use and Disuse - parts of the body used extensively become larger and stronger (Example: blacksmith’s arm) 2. Inheritance of Acquired Characteristics - modifications an organism acquires during its lifetime can be passed to offspring According to Lamarck, the giraffe’s long neck was acquired by stretching to get to the highest leaves. Slightly longer necks were passed on to the young and so on… and so on…. 1809-1882 British Naturalist proposed the idea of evolution by natural selection collected LOTS of evidence to support his ideas GREAT BRITIAN includes England, Sotland, and Wales UNITED KINGDOM includes - England, Scotland, Wales & Northern Ireland 1831- 1836 Darwin served as the ship’s naturalist HMS Beagle traveled around the world – main purpose was to chart the coast of South America Darwin…made observations, collected flora and fauna and studied geological features and land forms Figure 22.5 The Voyage of HMS Beagle relatively recent volcanic origin most animal species live nowhere else BUT they DO resemble species living on the mainland of South America Observed 13 types of finches Although similar, they seemed to be different species ◦ some were unique to individual islands ◦ some were distributed on 2+ islands Beaks were different He hypothesized that the beaks of the finches were evolutionary adaptations to different food sources It occurred to Darwin that a new species could arise from a ancestral form by the gradual accumulation of adaptations (good traits) to a different environment. early1840’s, Darwin had his major features of his theory of evolution by natural selection he did not rush out to publish his beliefs because his “ideas challenged fundamental scientific beliefs of his day” “Darwin was not only stunned by his discoveries, he was disturbed by them.” 1858 Darwin received a manuscript from Wallace who had come up with a theory of natural selection that was very similar to his own in 1859, Darwin published his book, The Origin of Species. natural variation - differences among members of a species are due to genetic variations genetic variation - variations in the genetic makeup of the members of a species 1. MUTATION…. a change in the DNA 2. GENE SHUFFLING…. the rearrangement of genetic information process by which organisms with favorable traits survive and reproduce at higher rates today, we use the phrase… “survival of the fittest” variation must exist among members of a species many more individuals are produced each generation than will survive – “struggle for existence” some individuals are better adapted so they survive and reproduce – “survival of the fittest” fitness – the ability of an organism to survive and reproduce – is the result of adaptations adaptation – any inherited characteristics that increases an organism’s chance of survival members of a species compete for food, space, mates, and other resources - competition according to Darwin, natural selection led to speciation….the development of a new species SPECIATION These are all the same species of beetle. dramatic color variations exist color variations are inheritable and are passed on those with coloration that best allows them to blend with their environment will survive, reproduce and pass on their coloration genes to their offspring Darwin found evidence that natural selection might work by studying artificial selection Artificial Selection… the breeding of domesticated plants and animals All domestic dogs were originally bred from wolves. Insecticide Resistance works much like antibiotic resistance in bacteria bugs susceptible to the insecticide die any bug that has a “resistance gene” will survive and reproduce Darwin perceived unity in life with all organisms related through descent from some unknown ancestor that lived in the remote past. As descendants of the first organism spilled into various habitats over millions of years, they accumulated diverse modifications or adaptations that fit them to specific ways of life. variation exists in populations more organisms are made than can exist in a population (variation is often inherited – genetically based) (called OVERREPRODUCTION - competition results) natural selection occurs through (1) interaction with the environment (2) variability among individuals in a population better “fit” individuals produce more offspring (they pass their “better fit” genes on to their offspring and so on…) the product of natural selection is…. adaptation of populations to their environment INDIVIDUALS CANNOT EVOLVE (1 individual with a new trait does NOT mean a new species has evolved) 1809 1825 1827 1827 1828 1831 1836 1838 A TIMELINE OF DARWIN’s LIFE - Charles Robert Darwin born in England - began pursuit of a medical career at University of Edinburgh in Scotland. - quit medical school - attended Christ's College at Cambridge - studying for the clergy - met Reverend Henslow, Professor of Botany at Cambridge to 1836 – served as naturalist on board the HMS Beagle – met geologists Lyell and Owen - Darwin read a book by economist, Malthus Malthus put forward the idea that as human populations grow and resources become scarce the weak die off in a struggle for existence. Darwin theorized that the same kind of relationship may exist in the wild. 1842 - wrote up a sketch of his ideas about evolution 1844 - wrote an "In the event of my sudden death" letter to his wife In it he requested that upon his death she promote the publication of his essay on evolution. 1858 - received a paper from Wallace in which Wallace had come up with a theory of natural selection that was very similar to his own 1859 - published The Origin of Species 1866 - the phrase, “survival of the fittest," was coined by Spencer and became a substitute for the phrase “natural selection" 1882 - Darwin died Chapters 14 & 15 Fossil Record Geography Comparative Anatomy Comparative Embryology Comparative Biochemistry FOSSIL…. a trace of a long-dead organism usually left in sedimentary rock and can be seen in different layers (strata) examples: trace (footprints, scat), mold (imprint), cast (rocklike model), replacement, petrified, amber, original material (bones, shells, seeds, feathers) There are many gaps in the fossil record Provide for a more detailed pattern of change There are many of these that share features of different species. ◦ Derived traits: new traits since ancestor (ex: feathers) ◦ Ancestral traits: retained traits of ancestor (ex: teeth) The 2 most common ways are… Relative Dating: based on law of superposition (lower fossils are older) Radiometric Dating: based on half-life (uses the decay of radioactive isotopes to measure the age) The study of the geographic distribution of life forms on Earth. The existence of similar but unrelated species was puzzling. Plate tectonics shifted Pangaea. Analogous Structures Homologous Structures Vestigial Structures similarities in the embryological development of species indicates common ancestry similarities in the biochemistry of species indicates common ancestry almost all living organisms have the same molecules: DNA, RNA, ATP, enzymes, etc. amino acid sequences are similar genetic code = A T C G (in ALL living things) Gene pool – combined genetic information of all the members of a particular population – typically contains 2+ alleles (forms of a gene) for each trait Due to natural selection – alleles may be “removed” from the population – thereby changing the genetic make up of the population Genetic drift – occurs in small population when individuals that carry a particular allele may leave more descendants than other individuals - over time, can cause an allele to become more common in a population Founder effect: occurs when small samples of a population settles apart from the population ◦ Ex: Amish & Mennonite Bottleneck: population declines to a very low number then rebounds ◦ African cheetahs 1. Stabilizing selection: eliminates extremes; the average expression leads to higher fitness (most common form) ◦ Baby’s birth weight 2. Directional selection: extreme version of a trait has more fitness ◦ Galapagos finches; Peppered moths In the 1800’s many moths in the British Isles began to become darker in color . In 1849, a coal-black mutant was found near Manchester, England. Within a century, this black form had increased to 90% of the population. The moth rests by day on tree trunks and is preyed upon by birds. In rural areas, the trunks of trees are encrusted with lichens. In areas where air pollution is severe, toxic gases and soot has killed the lichens and blackened the trunks. In these areas, the darker form of the moth has a much better chance of survival. PEPPERED MOTH 3. Disruptive selection: average traits are removed and extremes are left Ex: snakes with extreme color will camo 4. Sexual selection: operates in populations where males and females differ in appearance Ex: birds Two types will prevent gene flow Prezygotic isolating mechanism – prevent fertilization from occuring ◦ Behavioral, geographical, ecological Postzygotic isolating mechanism - a sterile offspring is made ◦ Liger Allopatric speciation: physical barriers divide populations (most common) ◦ Mountains, rivers, etc. Sympatric speciation: no physical barriers ◦ Insects, plants (polyploids) Gradualism: evolution occurs in small, gradual steps Punctuated equilibrium: rapid spurts of genetic change cause quick divergence the theory that eukaryotic cells arose from a symbiotic relationship among different prokaryotic organisms