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• All living things share a common ancestor. • We can draw a Tree of Life to show how every species is related. • Evolution is the process by which one species gives rise to another and the Tree of Life grows • The theory of Evolution deals with how evolution happens. Our understanding of this process is always changing. • Evolution is also a fact as there is a huge amount of indisputable evidence for its occurrence. Most scientists in Darwin’s day thought the Earth was only a couple thousand years old They believe that Earth had not changed, nor had any of its species These two men helped scientists recognize that Earth is many millions of years old and the processes that changed Earth in the past are the same ones operating now – father of modern geology; hypothesis regarding geological forces that have shaped Earth – echoed Hutton; past events that affected the earth are still happening One of the first scientists to recognize that living things have changed over time Species were descended from other species Also realized that organisms had adapted to their environment By selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime The idea that organism’s alter their body by using it in new ways All organisms have an innate tendency toward complexity and perfection Organisms will continually change and acquire features that bring them closer to this goal! Believe acquired traits could be inherited If an organism’s body was altered, it would pass that trait to its offspring Example? 1809 - 1882 Most influential contributor to thoughts about evolution Wrote The Origin of Species 1859 – published Presented evidence for changes in species through Natural Selection Traveled around the world; notable work in the Galapagos Islands 5 year round-the-world voyage 1831 - at age 22 H.M.S. Beagle Ship’s naturalist At beginning of trip - believed species were immutable Collected and examined the species that inhabited the regions the ship visited Fossils, coral ,plants, animals Volcanic islands - 3.5 mya Isolated, west of Ecuador All inhabitants are descended from species that arrived on islands from elsewhere Finches Tortoises Iguanas Blue-footed Booby 13 species of finches Share many morphological features Differ in several ways Beak size Beak shape Food eaten Evolved from a single species He attempted to correlate variations in their traits with environmental challenges WET ISLANDS Short neck Domed shell Long neck Flared shell DRY ISLANDS Marine Iguana Algae eater Land Iguana Terrestrial vegetation The characteristics of many animals and plants varied noticeably among the different islands of the Galapagos Groups of 3-4 4 trials Start each new generation with 100 butterflies Be careful with the butterflies! Natural selection results in changes in the inherited characteristics of a population. These changes increase a species’ fitness (ability to survive and reproduce) in its environment Darwin’s Evolutionary Ways of Thinking Darwin publishes Origin Of Species in 1859 Prompted after Wallace publishes essay Words/phrases we are introduced to Artificial selection Struggle for existence Fitness Adaptation Survival of the fittest Nature provides variation, humans select variation that they found useful Livestock Members of the same species compete What are they competing for? What Darwin called the ability of an individual to survive and reproduce Fitness is a result of adaptation Adaptation any inherited characteristic that increases an organism’s chance of survival Individuals with characteristics that are better suited to their environment – adaptations that enable their fitness – survive and reproduce most successfully Over time, natural selection results in changes in the inherited characteristics of a population. These changes increase a species’ fitness in its environment Principle proposed by Darwin Over long periods of time, natural selection produces organisms that have different structures, establish different niches, or occupy different habitats RESULT species today look different from their ancestors All species, living and extinct, are derived from a common ancestor A single “tree of life” links all living things! Darwin argued living things have been evolving on Earth for millions of years Evidence for this process can be found: ▪ Fossil record ▪ Geographical distribution of living species ▪ Homologous structures of living organisms ▪ Similarities in embryology Fossils remains of ancient life Darwin compared fossils from older rock layers to those in younger rock layers to document the change of life on Earth © World Health Org. en.wikipedia.org/wiki/Image:Eopraptor_sketch5.png © NASA origins bacteria complex cells dinosaurs humans The fossil record shows a sequence from simple bacteria to more complicated organisms through time and provides the most compelling evidence for evolution. Species living on different geographical areas had each descended from different ancestors However, because of similar ecological conditions they were exposed to similar pressures of natural selection similar features Structures that have different mature forms in different organisms, but develop from the same embryonic tissue. Organs of many species are so reduced in size that they are just traces of homologous organs in other species Examples: miniature legs, tails Appendix Wisdom Teeth Tailbone Particular Ear Muscles VNO Plica semilunaris Embryology of many animals with backbones are very similar WHAT DOES THIS MEAN? Certain embryonic cells develop in the same order and in similar patterns to produce the tissues and organs of all vertebrates At one point… you looked like this. Thought you should know… Individuals organisms differ, and some of this variation is heritable Organisms compete for resources Each organism has different advantages/disadvantages organisms best suited survive and pass their traits to offspring Species today are descended with modification from ancestral species; common ancestor, single tree of life