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Founder of modern evolutionary theory 1831 Darwin became a naturalist on the HMS Beagle Studied animal and plant life on mapping expedition to South America.

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Presentation on theme: "Founder of modern evolutionary theory 1831 Darwin became a naturalist on the HMS Beagle Studied animal and plant life on mapping expedition to South America."— Presentation transcript:


2 Founder of modern evolutionary theory 1831 Darwin became a naturalist on the HMS Beagle Studied animal and plant life on mapping expedition to South America and South Pacific


4 Darwin studied anatomy of insects, reptiles, birds and flowering plants

5 Galapagos Tortoises The inhabitants...state that they can distinguish the tortoise from different islands; and that they differ not only in size, but in other characters. Captain Porter has described those from Charles and from the nearest island to it, namely Hood Island, as having their shells in front thick and turned up like a Spanish saddle, whilst the tortoises from James Island are rounder, blacker, and have a better taste when cooked.--- Charles Darwin 1845


7 That there must be a struggle for existence among all individuals Organisms must struggle for –Food –Space –Prey

8 From ancient times, most people believed all living things were created by a divine being at the same time and remained unchanged. By the time Darwin set sail, numerous discoveries, including a rich fossil record, had turned up importance evidence that caused some scientists to question these ideas.

9 Geologists James Hutton and Charles Lyell –After examining Earth in great detail, recognized that Earth is many millions of years old, and the processes that changed Earth in the past are the same processes that operate in the present. –Ex: volcanoes, earthquakes, erosion, continental drift, etc. The Grand Canyon, with its many layers of rock, was formed over millions of years by the Colorado River (erosion).

10 Jean-Baptiste Lamarck - French naturalist –Published hypothesis of Inheritance of Acquired Characteristics same year Darwin was born –Proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. Traits could then be passed on to offspring Over time would lead to change in species



13 Thomas Malthus - English economist –Reasoned that if the human population continued to grow unchecked, eventually there would not be enough space and food for everyone Forces such as war, famine and disease work against the growth –Darwin realized this was even more true for plants and animals because humans produce far fewer offspring

14 Upon returning to England, Darwin began studying his specimens and filling notebooks with ideas. Shared ideas with friends but reluctant to publish -- understood his ideas challenged scientific and religious beliefs of his day After more than 25 years -- published On the Origin of Species in 1859

15 Charles Darwin Published: “On the Origin of Species”


17 Only some of the population survive long enough to produce offspring

18 Darwin’s observations led to the conclusion that individuals have different variations of traits that can be inherited Darwin bred pigeons with desirable variations and he was able to produce offspring with the same features

19 Breeder selects the particular traits Darwin wondered if there was some force in nature similar to artificial selection


21 Mechanism for change in populations that occurs when organisms with favorable variations for a particular environment survive, reproduce and pass variations on to the next generation Organisms with less favorable variations are less likely to survive and pass on traits to the next generation


23 Tendency toward Overproduction For example: Fish lay thousands of eggs Most of these eggs will not survive

24 Individuals Exhibit Variations Example: Fishes may differ slightly in color, fin and tail size and speed

25 Individuals with favorable traits survive and pass on those genes Ex: A fast fish with camouflaged skin will be more likely to survive and reproduce. Thus, passing along the more desirable traits to future offspring.

26 Populations evolve, or change over time Gradually, the offspring of the survivors make up a larger portion of the population. After many generations the population may look entirely different.


28 Changes in structure or body parts that aide in survival

29 To copy the appearance of another species

30 Color adaptation so organism blends with its surroundings

31 May take millions of years to develop or they may be rapid Ex: Slow---Sightless mole rat Fast: Antibiotic resistance

32 Fossils show change over time The Fossil Record

33 Geographical Distribution –Organisms live in different areas of the world, but have similar adaptations –Different ancestors, but similar environmental pressures acting against it Descent with modification

34 Modified structure that is seen among different groups of descendants

35 Similar in function, but different in structure Ex: Bird Wing/Butterfly Wing

36 Any body structure that is reduced in function in a living organism but may have been used in an ancestor

37 Fish, reptiles, birds and mammals look similar during embryological development


39 If you know the genotypes of all the organisms in a population, you can calculate the allelic frequency. A population in which the frequency of alleles does not change is in genetic equilibrium.



42 Favors Average Individuals in a population

43 Favors either of the extreme forms of a trait

44 Both extreme forms of a trait are favored

45 Speciation, or the formation of new species, can only occur when either interbreeding or the production of fertile offspring is somehow prevented: Reproductive Isolation –Geographic isolation –Temporal isolation –Behavioral Isolation

46 Occurs when two populations are capable of interbreeding but have differences in courtship rituals or other reproductive strategies that involve behavior. Ex. Eastern and Western Meadowlarks –Habitat overlaps, but will not mate with each other because they do not respond to each others song!

47 Two populations are separated by geographic barriers such as rivers, mountains, or bodies of water. Ex. Colorado River separating the Abert squirrel and the Kaibab squirrel (about 10,000 years ago).

48 Two or more species reproduce at different times. Example: Orchids. Release pollen on different days, so they cannot pollinate each other.

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