Different interpretations of cetacean evolutionary history 4/19/10 Aim: What is Evolution by Natural Selection Do Now: How do we know all life on earth is related? Homework Read pp. 375 379 p. 379 # 1,2,3 Apr 21 6:33 AM May 13 12:28 PM Do Now LE 1: Copy Now Natural Selection Evolution, the change of species over time, is the central unifying theme of biology Biological evolution occurs through natural selection. Natural selection is the result of overproduction of offspring having variations, these variations struggling for survival, and the subsequent survival and increased reproduction of those best adapted to a particular environment. Mutations One source of the variation driving the process of evolution is mutation. Mutation is the change in DNA of an organism which may result in that organism being different than its parents While there are many causes of mutations, some factors are known which rapidly increase the incidence of mutation. The degree of kinship between organisms or species can be estimated from the similarity of their DNA sequences; this similarity often closely matches organisms' or species' classification based on anatomical similarities. The differences in species produced by inheritable mutation is a driving force in the process of natural selection. May 13 7:00 AM May 13 7:22 AM Variation Variations are differences between groups of organisms of one species. Mutation is one source of variation between different groups within a species. variation of organisms within a species increases the likelihood that at least some members of the species will survive under changed environmental conditions May 13 7:05 AM Apr 21 6:51 AM 1
Darwin's voyage on the HMS Beagle, 1831 1836 Darwin's Theory of Evolution by Natural Selection 1. Overproduction 2.Variation 3. Selection 4. Adaptation Apr 21 6:53 AM Apr 21 7:09 AM Theory of Natural Selection Overproduction: Within a population more offspring are born than can possibly survive Competition: Since the number of individuals in a population tends to remain constant from generation to generation due to limited resources, a struggle for survival occurs Survival of the Fittest: The individuals who survive are the ones best adapted to exist in their environment due to the possession of variations that best suit them to their environment. genetic variability within a species is chiefly due to mutation and genetic recombination variation of organisms within a species increases the likelihood that at least some members of the species will survive under changed environmental conditions Reproduction: Variations assist or hinder individuals in their struggle for survival The best adapted individuals survive and reproduce, passing on the favorable variations to their offspring Speciation: As time and generations continue, adaptations are passed on and new species may evolve from a common ancestor. History of Evolutionary Theory Lamarck proposed that organisms change over time as they adapt to changing environments thought (incorrectly) that changes due to use or disuse of a trait would be passed on t offspring Suggested to Darwin that inheritance played a role in Evolution Darwin voyage of HMS Beagle 1831 1836 Proposed that organisms change over time through a process called natural selection Evolution is a change in inherited characteristics in a population from one generation to another Theory predicts that over time the # of individuals w/ beneficial traits will increase in a population Overproduction Variation Selection/ Competition (Survival of fittest) Adaptation traits of most fit will become more common; May 13 7:24 AM Apr 23 8:41 AM Darwin's Theory of Evolution by Natural Selection A species is a population of organisms that interbreeds and has fertile offspring. Living organisms have descended with modifications from species that lived before them. Forces that Influence Evolution Environment Species can become more favored or not due to Environmental Changes Natural selection explains how this evolution has happened: More organisms are produced than can survive due to limited resources Geographic Isolation Organisms struggle for the necessities of life; there is competition for resources Individuals in a population vary in their traits; some traitts are heritable Some variants are better adapted to survive and reproduce under local circumstances than others Reproductive Isolation Better adapted individuals (The most Fit) are more likely to survive & pass on their traits, thereby passing on their genes to the next generation Species whose individuals are best adapted survive; others become extinct Apr 21 6:53 AM Apr 23 8:36 AM 2
EvolutionIntro.notebook Aim: How does the Evolution by Natural selection explain diversity of life? Do Now: How did the Galapagos finches help Darwin to understand evolution? Homework: Vocabulary: Natural Selection, adaptation, fossil, homologous Read pp.380 385 p.385 # 1,2 Apr 21 6:38 AM Apr 21 6:45 AM Darwin wondered about the changes in shape of bird beaks from island to island. So called cactus finches boast longer, more pointed beaks than their relatives the ground finches. Beaks of warbler finches are thinner and more pointed than both. Researchers at Harvard Medical School have taken the story one step further. Using modern genetic analyses, they found a molecule that regulates genes involved in shaping the beaks of Darwin finches. "Calmodulin is a protein that binds and activates certain enzymes, which triggers a signal that eventually turns specific genes on or off,". These signals alter the behavior of cells responsible for beak sculpturing. Apr 21 6:42 AM Aim: What is the evidence for Evolution? Apr 21 6:46 AM Coelecanth A prehistoric fish out of time Do Now: Did you have the same findings in the lab for the white & brown mice? Baby Coelecanth found near indonesia, 2009 Following a supposed extinction of 65 million years, head lined into human consciousness with its discovery alive in 1938. Called "Old Four Legs" and the "Living Fossil," Apr 23 12:04 AM Apr 25 6:13 PM 3
Evidence for Evolution Fossil Record traces of organisms from the past saw patterns in the record that species change over time noticed gaps Transitional Forms organisms that show an intermediate state between an ancestor and its descendant cross section through a sub adult thigh bone of the duckbill dinosaur Maiasaura. The white spaces show that there were lots of blood vessels running through the bone, which indicates that it was a fast growing bone. Nicholas Steno's anatomical drawing of an extant shark (left) and a fossil shark tooth (right). Steno made the leap and declared that the fossil teeth indeed came from the mouths of once living sharks. (17th Century) Apr 23 8:49 AM Apr 23 11:13 AM Aim: What influences Natural Selection? Do Now: Did white mice & Brown mice experience the same outcomes in the Lab? Explain what happened Apr 22 9:00 AM Apr 25 6:13 PM Apr 25 6:24 PM Apr 22 11:56 PM 4
Geographic Isolation Reproductive Isolation Apr 22 11:58 PM Apr 23 12:00 AM How Fast is Evolution? Punctuated Equilibrium Apr 23 12:00 AM Apr 23 12:02 AM Gradualism Apr 23 12:03 AM May 9 7:14 AM 5