Ch 15- Darwin’s Theory of Evolution Evolution- change over time – Process by which modern organisms have descended from ancient organisms Theory- well supported explanation of phenomena that has occurred in the natural world Evolution is a theory that has been well tested concept that is supported by evidence

Voyage of the Beagle What was Charles Darwin’s contribution to science? – Made numerous observations and collected evidence-led to revolutionary hypothesis about the way life changes over time – Now supported by large body of evidence Pattern of diversity – Grassland in Argentina, Australia, and Europe all supported different sorts of organisms

Fossils- preserved remains of ancient organisms – Resembled organism living today, others were like no other organisms – Why had so many of these species disappeared? Galapagos Islands km west of South America – Close together, very different climates Observed the characteristics of many animals and plants varied noticeably among the different islands of Galapagos – Birds’ different shaped beaks Welcome to Discovery Education Player

Lamarck’s Evolution Hypotheses Proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime – Traits could be passed on to offspring – Over time this process leads to change in species One of first scientists to develop scientific hypothesis of evolution

Origins of Evolutionary Thought Hutton and Lyell- suggested Earth was old enough for evolution to have occurred Thomas Malthus- suggested human population would continue to grow but sooner or later living space would be insufficient

Sec 3- Darwin Presents His Case 1859 Darwin published his findings in his book, On the Origin of Species- natural selection was the driving force behind evolution Artificial selection- selection by humans for breeding of useful traits from the natural variation among different organisms – Nature provided the variation, and humans selected the variation they found useful

Evolution by Natural Selection Struggle for existence- members of each species competes regularly to obtain food, living space, and other necessities of life – Predators that are faster can catch more prey – Prey that are faster, better camouflaged can avoid being caught Fitness- the ability of an individual to survive and reproduce in its specific environment Adaptation- any inherited characteristic that increases an organism’s chance of survival – Structural characteristics, physiological processes, behavior in animal in which they hunt in groups

Survival of the fittest- individuals that are better suited to their environment survive and reproduce most successfully= natural selection Over time natural selection results in changes in the inherited characteristics of a population – These changes increase a species fitness in its environment – Cannot be seen directly, observed as changes in population over many successive generations Welcome to Discovery Education Player Descent with modification- species descend with changes from other species over time – Natural selection produces organisms that have different structures, establish different niches, occupy different habitats – Common descent- all species, living and extinct, were derived from common ancestors

Evidence of Evolution Darwin argued living things have been evolving on Earth for millions of years Evidence – Fossil record – Geographical distribution of living species – Homologous structures of living organisms – Similarities in early development, or embryology

Homologous Body Structures Homologous structures- structures that have different mature forms but develop from the same embryonic tissues – Provide strong evidence all four limbed vertebrates have descended with modifications from common ancestors Vestigial organs- organs in animals reduced in size that serve little to no function – Miniature legs, tails