* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download NATURAL SELECTION AT WORK
Survey
Document related concepts
Sexual selection wikipedia , lookup
Microbial cooperation wikipedia , lookup
Evolving digital ecological networks wikipedia , lookup
Sympatric speciation wikipedia , lookup
Paleontology wikipedia , lookup
Punctuated equilibrium wikipedia , lookup
Evolutionary history of life wikipedia , lookup
Natural selection wikipedia , lookup
Organisms at high altitude wikipedia , lookup
Theistic evolution wikipedia , lookup
Hologenome theory of evolution wikipedia , lookup
Inclusive fitness wikipedia , lookup
Evidence of common descent wikipedia , lookup
Population genetics wikipedia , lookup
Transcript
THEORY OF EVOLUTION “Evolution explains the diversity & relatedness of life on earth” GPS – Evolution (Population Genetics and Speciation) The Idea of Evolution: Descent with Modification • Living things share common characteristics because they are descended from common ancestors. • Living things are diverse because each species is adapted to its own habitat and way of life. Who was Charles Darwin? • 1831, became an unpaid naturalist on board the HMS Beagle. • Observed plants and animals on the Galapagos Islands… Darwin’s Investigations of the Galapagos Islands • Each island had its own species of giant tortoise in response to the type of vegetation found on each island. • Marine iguanas (only found on the Galapagos) have similarities to the land iguanas found in South America. • The 13 species of finch on the islands are similar except for each having a beak adapted to a particular way of life. CHARLES DARWIN DEVELOPS A THEORY “On the Origin of Species by Means of Natural Selection” Darwin’s Observations: 1) Individuals in a population are different from one another. 2) Organisms produce more offspring than the environment can support. 3) In spite of the large numbers of offspring, population size tends to remain the same. 4) Environments are constantly changing. CHARLES DARWIN DEVELOPS A THEORY “On the Origin of Species by Means of Natural Selection” 1) In each population there is a competition for available resources; only some organisms survive. 2) Individuals with favorable variations are more likely to survive and reproduce. (survival of the fittest) 3) The favorable variation that allows survival accumulates and eventually appears in the entire population. (adaptation) NATURAL SELECTION AT WORK “Natural Selection Provides a Mechanism for Evolution” • Natural Selection Check List: aVariation exists between individuals. aOverproduction/struggle for survival. aSurvival of the fittest. (survive and reproduce) aAdaptation increases in the population. The maintenance of variation is beneficial because populations that lack variation may not be able to adapt to new conditions and may become extinct. What causes Variation? • Mutations and genetic recombination. • Natural Selection reduces, but does not eliminate, the range of phenotypes. A Mutation is a change in the DNA sequence Spontaneous mutations affect the amino acid sequence of a protein. This new protein may be beneficial, harmful or have no affect at all. New mutations are constantly being generated in a gene pool. • A gene pool is all the genes in a population. • Mutation is an important source of genetic variation within a gene pool. How does Natural Selection determine which genetic traits are passed on? • Beetles with brown genes escaped predation and survived to reproduce more frequently than beetles with green genes, so that more brown genes got into the next generation. Over the past 60 years penicillin has been used to treat bacterial infections. • Now, however, penicillin has become ineffective at killing many types of bacteria. What helped the bacteria become more resistant? Organisms Differ in Fitness What is Fitness? • The most fit organisms reproduce and leave more offspring than the less fit organisms. • Natural Selection is the change caused by the survival and reproduction of specific individuals. Natural selection causes change within populations • Organisms best suited to their environment survive and pass on their traits through their “genes”. • The frequency of these “genes” builds up in the population. • When this “genetic trait” builds up in the entire population it is called an adaptation. Natural Selection determines the differential survival of groups of organisms • An adaptation is a trait that helps an organism be more suited to its environment. • Natural selection results in the adaptation of populations to their specific environments. Industrial Melanism “An Example of Natural Selection” • The Peppered Moths of Manchester, England come in two varieties, one darker than the other. • Before the industrial revolution, the dark moth was rare; however, during the industrial revolution the light moth seldom appeared. • Why? SPECIATION “Splitting of one species into two species” Isolation leads to species formation • Geographic isolation physically separates groups within a population. • When populations become separated, different environmental pressures can create differences between the two groups. Allopatric speciation is created by a geographic barrier Sympatric speciation is when populations develop a genetic difference • If these differences become so extreme that the two populations can no longer interbreed they can, at that point, be considered two different “species”. Reproductive isolation keeps newly forming species from interbreeding Why is species diversity beneficial? • Increased diversity among species increases the chances that some species will adapt to survive future environmental changes. Fossils Tell The Story … Fossils - preserved or mineralized remains or traces of an organism that lived long ago. THE FOSSIL RECORD - Provides evidence for succession of life over time (example: the evolution of the horse). - Provides transitional links between groups of organisms (example: Archaeopteryx - links reptiles to birds). What is a Mass Extinction? • Periods when a large percentage of existing species becomes extinct within a relatively short period of time. Is All life wiped out during a Mass Extinction? • No, but one mass extinction lost as much as 95% of the life on earth. Convergent Evolution The independent development of similar structures in organisms that are not directly related Convergent evolution is usually seen in animals and plants that live in similar environments Analogous structures tend to be alike but constructed differently e.g. insect wings and bird wings. The relationship between insect wings and bird wings is analogous The relationship between different bird wings is homologous Co-evolution Two species that interact with each other (predator/prey; mutualistic; parasite/host;) and act as selection pressures on one another Long legs Good hearing Sharp eyesight Co-evolution What can cause a Mass Extinction? • Environmental changes, diseases, loss of resources, predation, extraterrestrial events What do Mass Extinction do in terms of evolution? - Mass Extinctions allow evolution to take a new direction. - Episodes of speciation are the most dramatic after a mass extinction has cleared the way for new species take over recently vacated areas. Evidence of Evolution Taxonomy: Classification of life forms. Homologous structures: Structures that are similar because of common ancestry (comparative anatomy) Divergent Evolution • When species with a common ancestor evolve into very different forms. • Evidence: homologous structures – May have the same components but different a function and or structure. Evidence cont’d Comparative embryology: Study of structures that appear during embryonic development. Molecular biology: DNA and proteins (amino acids) EVIDENCE CONT’D VESTIGIAL STRUCTURES: STRUCTURES THAT DO NOT SEEM TO HAVE A FUNCTION What adaptation would increase the white turtle’s fitness? www.msnbc.com Evolution due to natural selection • Ex: white turtle will not survive in nature (no evolution) • If sea becomes white, then white turtle will have the advantage, thus green turtles become extinct Can you see me? http://www.trendhunter.com/images/phpthumbnails/28656_4_468.jpeg Can you see me? Can you see me? Can you see me?