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History of Life and Evolution Notes – part I History of Life o Biogenesis: o All living things come from other living things Spontaneous Generation: Living things could arise from nonliving things Redi’s experiment o Previous idea: Flies were created from rotten meat o Redi: Meat kept away from adult flies would not produce maggots Spallanzani – tried to disprove that microorganisms arose from a “vital force” in the air Pasteur – improved spallanzani’s experiment to eliminate the flaw of “no air” What is Evolution? o Dictionary: The gradual development of something; especially from a simple to complex form. o Text book: Generally, in biology, the process of change by which new species develop from pre-existing species over time 18th Century Ideas o All species were permanent and unchanging o The earth was only a few thousand years old and unchanging Uniformitarianism o Idea by Charles Lyell that said geologic processes happed slowly over time and that some features of the Earth may take millions of years to form. Jean-Baptiste Lamarck o French Naturalist o 1809 o Lamarck’s Hypothesis: by selective use or disuse of organs, organisms acquire or lose certain traits. These traits could then be passed on to their offspring. o Lamarck believed over time, this process led to change in a species. Tendency toward perfection - All organisms have an innate tendency toward complexity and perfection, so they are continually changing to be more successful in their environment Use and disuse - Organisms can alter their bodies/organs by use or disuse Inheritance of acquired traits - Organisms can pass on those altered body parts/organs to the offspring o Lamarck the Loser – he was wrong! o First to develop a hypothesis of evolution o First to realize organisms adapt to their environment o But, Behavior has no effect on inheritable characteristics Charles Darwin o 1809 – 1882 o Naturalist – study of nature and the natural world o Sailed on the HMS Beagle in 1831 o Every time the ship docked, Darwin went ashore to collect plant and animal specimens o Darwin’s observations piqued his interest in the diversity of life he observed. o Darwin even found evidence that suggested species once present on earth had vanished. o Researchers today speculate that 99.9% of all species that ever inhabited earth are now extinct. Galapagos Islands o The islands were close together, but had very different climates o Smallest and lowest islands = hot, dry & barren o Hood Island = sparse vegetation o Higher islands had greater rainfall and a different assortment of plants/animals o Isabella Island = rich vegetation Darwin’s Idea o Darwin observed that the plants and animals varied noticeably among the different Galapagos Islands. o However, Darwin wondered if animals living on different islands had once been members of the same species – originating from the same South American ancestor Descent With Modification o The Origin of Species by Means of Natural Selection – 1858 o Every species – living or extinct – descended by reproduction from preexisting species o AND o Species must be able to change over time Darwin’s reasoning for Natural Selection o Overproduction – more offspring produced than can survive o Genetic Variation – within a population, individuals have different traits. New traits may appear spontaneously. o Struggle to survive – constant competition may cause some variations/traits to be advantageous o Differential Reproduction – Organisms with the best adaptations will survive and reproduce, thus the advantageous adaptations will become most prevelant in the population. o Evolution by Natural Selection o Struggle for existence – each member of a species competes regularly for food, living space and other necessities of life. Survival of the Fittest o How well suited an organism is to it’s environment o Does fittest mean strongest? o Does fittest mean in the best shape? Fitness – the ability of an individual to survive and reproduce o The result of adaptations Fittest – the individuals most capable to survive and reproduce for multiple generations o The traits selected as the most useful for survival and reproduction are determined by the organisms environment Natural Selection accounts for Descent with Modification as species become better adapted to different environments. Adaptation vs. Acclimatization o Adaptation - Changes in traits in populations over time Example: White moth population becoming a black moth population after 5 generations. o Acclimatization – individual organism changes physiologically Example: growing thicker fur in winter Adaptations o Any inherited characteristic that increases an organism’s ability to survive and reproduce o o Anatomical or structural characteristics Porcupine quills - protection Longer necks in giraffes – find food Physiological processes o How a plant performs photosynthesis Instinctual Behaviors Hunting in packs Living in burrows