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Cpbio ch 13 evolution
This document provides an overview of Charles Darwin and the key aspects of his theory of evolution by natural selection. It discusses Darwin's influences and education, his famous voyage on the HMS Beagle where he made observations that influenced his thinking, such as the variation in beak shapes of finches on the Galapagos Islands. The document also summarizes Darwin's theory of natural selection, the process by which organisms better adapted to their environment tend to survive and pass on their traits. It provides examples of evidence that supports the theory of evolution, such as the fossil record, comparisons of biological molecules, homologous and vestigial structures.
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Cpbio ch 13 evolution
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- 2. Charles Darwin, 1808- 1882 WHATABOUT HIM??? born into a wealthy family medical school drop-out - thought surgery was “brutal” his father pushed him into becoming a clergyman and dropped-out of this as well eventually followed his interests in ecology, geology and taxidermy author of “On the Origin of Species” - 1859, provided evidence for evolution by natural selection
- 3. SOME OF DARWIN’S INFLUENCES… CharlesLyell, 1797-1875 - “Principles of Geology”, described landforms as the result of gradual processes over time (Darwin saw evidence of this on his voyage - bands of coral fragments in volcanic rock) John Henslow, 1796-1861 - botanist/geologist, Darwin’s mentor
- 4. SOME OF DARWIN’S INFLUENCES… ThomasMalthus, 1766-1834 - “An Essay on the Principle of Population”, proposed that if the human population continues to grow “unchecked” it would soon reach carrying capacity…then what??? "In October 1838, that is, fifteen months after I had begun my systematic inquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from long- continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The results of this would be the formation of a new species. Here, then I had at last got a theory by which to work". Charles Darwin, from his autobiography. (1876)
- 5. DARWIN’S VOYAGE was selectedas an unpaid geologist/naturalist voyaged on the HMS Beagle purpose of voyage was to chart the coastline of South America over 2 years Darwin collected fossils and living organisms and took many notes unfortunately…he was seasick for most of the trip
- 6. WHAT DID HESEE IN THE GALAPAGOS ISLANDS??? Galapagos Islands - volcanic islands west of Ecuador in the Pacific Ocean (16 islands - 5 inhabited), some are still forming observed birds (later determined to be finches) - similar in appearance with differing beaks since these were islands, all of the birds were assumed to have one common ancestor each bird was adapted to eating a particular food - seeds, insects, etc.
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- 8. EVOLUTION BY NATURAL SELECTION???Darwin'stheory (yes, you need to know this!): within a given species, more individuals are produced than can survive due to limited resources (food, shelter, mates) as a result, there is a struggle for existence/competition for limited resources individuals within a species show variation - no two individuals are exactly alike those with advantageous traits have a greater chance of survival, and therefore of reproducing individuals produce offspring that tend to resemble their parents (inheritance) advantageous traits that promote survival are inherited by offspring, so individuals possessing those traits will become more common in the population over successive generations because they are more likely than individuals not possessing those traits to survive and reproduce
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- 10. WHAT IS EVOLUTIONBY NATURAL SELECTION??? Simply stated: in nature individuals compete for limited resources and based on those resources, nature selects the best suited for the environment = natural selection let’s look at an example… and another… and another… and another…
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- 12. More on Darwin… Naturalselection…less wordy more organisms are produced than can survive there is competition for resources those with favorable traits (depending on what the competition is over) win the resource(s) these are the organisms that survive and reproduce (and make more like themselves) favorable traits are the result of differences between organisms differences are the result of random mutations
- 13. TERMS TO KNOW adaptation- change in a species that makes it better suited for its environment natural selection - “nature” selects organisms with better suited traits to survive and reproduce, over time organisms become better adapted isolation leads to the development of new species - when organisms are isolated and cannot breed, they become more different over time
- 14. EVIDENCE FOR EVOLUTION1. fossils- show a pattern of development, all organisms evolved from earlier life forms FYI…there are few “missing links” or intermediate forms or transitional species archaeopteryx is one of the few “missing links” - it has both reptile and bird-like features
- 15. 2. biological molecules- comparing proteins and nucleic acid sequences can reveal a common ancestor for example - comparing differences in hemoglobin (a protein that carries oxygen in your bloodstream) - more distant ancestors have more differences
- 17. 3. comparing anatomycan reveal similarities homologous structures -similar structures, although they may have different functions/are adapted to different environments
- 18. analogous structures –similar function, but occur in unrelated species adapting to similar environments
- 19. 4. biogeography –studies locations of organisms around the world closely related organisms can be adapted to different environments that are nearby (ex. – Darwin’s finches) unrelated organisms can have similar adaptations to similar environments that are far apart (ex. – Australia’s mammals that resemble mammals in similar environments but are unlike in that they are all marsupials)
- 21. 5. vestigial structures- structures that have less important/no function as compared to related organisms for example - the human tailbone (coccyx), ear muscles and the gene to make vitamin C other vestigial structures - baleen whale pelvis and femur, splint in horses, pelvis and femur in some snakes
- 22. 6. comparing embryos- early in development many organisms share similar characteristics
- 23. phylogeny – putsevidence together to show relationships among organisms
- 24. GRADUALISM VERSUS PUNCTUATED EQUILIBRIUMgradualism -evolution occurs slowly over a long period of time, organism changes many times for example – human evolution…many small changes occurred…larger brain size, bipedalism punctuated equilibrium - major environmental changes may cause evolution to occur in spurts, rapid change followed by periods of no change for example – species that show few “transitional species” such as T. rex