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Transcript
Evolution of Living Things Adaptation • Characteristics that helps an organism survive and reproduce in its environment • When disturbed, they inflate their bodies. A conspicuous spadelike tubercle on each foot pushes soil to either side as the frog shuffles backward into the ground. They spend much of the year underground, but come to the surface after a heavy rain to breed. Squirrel monkeys move through the trees by leaping. They have thighs that are shorter relative to their lower legs; this allows more jumping force. They distribute a musky glandular secretion throughout their fur (especially on tail) as scent to mark territory or to leave a trail for others of the troop to follow as they go through the trees. This odor turns away hunters who might otherwise kill them for food. • Very agile. Furry pads on feet are good for rock climbing. Will actively dig for water, sometimes up to one meter deep; however, they conserve body water by hiding in hollows under granite boulders during hottest part of day. Wallaroos are the kangaroo best adapted to heat and dryness. Heat sensors along the upper lip as well as its keen sense of smell help it to find prey. As with other snakes, the python's loosely hinged jaws can be stretched far apart, enabling it to swallow animals with bodies much larger in diameter than the python's head. They are good climbers and have prehensile tails. To open the Abalone shell they place a small rock on their chest and smash the shell against it. Sea otters are one of the few mammals, beside humans, that use tools. They will use strands of kelp to tie themselves into the kelp beds for a secure night's sleep. Air trapped in their fur keeps them warm and buoyant Adaptations: Cockroach and chameleon • Group of organisms that can mate with on another to produce fertile offspring Species Do Species change over time? • Evolution: process by which populations accumulate inherited changes over time. • Evolution Could birds have evolved from dinosaurs? Evidence of Evolution • Fossil Record: provide a historical sequence of life • Fossils are solidified remains or imprints of once living organisms Vestigial Structures • Remnants of once useful structures. • Whales possess a femur and pelvis, but these bones are no longer useful to the mammals Comparing Organisms • Comparing skeletal structures • Comparing DNA • Comparing embryonic structures • Comparing DNA: • All organisms contain the same limb bones- humerus, radius, ulna, etc, but they evolved to look different over time in length. • Homologous structures are structures from different organisms that look similar because the organisms descended from common ancestors (according to evolution). Comparing Embryonic Structures • Scientists look at embryos of different organisms and find that many embryos resemble one another. Before Darwin • French Scientist Jean Baptiste de Lamark ( 17741829) • “inheritance of acquired characteristics” • Passed acquired traits to their How does Evolution Happen? Charles Darwin: • 1831 he went on voyage on the HMS Beagle for five years. • He observed thousands of species and collected many different types of fossils. • Finches living on Galapagos Islands differed slightly from the finches in Ecuador. • Darwin concluded from his years of research that individuals having advantageous variations are more likely to survive and reproduce than those without the advantageous variations… Evolution by Natural Selection. Natural Selection •The process by which organisms with favorable variations survive and reproduce at a higher rate. •Darwin learned from farmers and animal and plant breeders •Selective breeding: breed only individuals that have desired traits. • Darwin was aided in his research by the book Principles of Geology, written by Charles Lyell, where he learned the age of Earth. • Darwin also learned from Thomas Malthus’ essay on the Principle of Population, which helped him realize that animal species often produced too many offspring, and starvation, disease, and predators affected their population. • Then in 1858, Russell Wallace (1823-1913) came up with the same idea, therefore, Darwin finished his book The Origin of Species in 1859. Theory of Natural Selection explains how a population changes over many generations in response to its environment. Formation of new species: • Speciation: when two populations can become so different that they can no longer interbreed. 1. Separation: • Populations become isolated from one another 2.Adaptation: • When the environment changes so may the population that lives there. 3. Division – Two populations over time may become so different they can no longer interbreed