copyright cmassengale

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Evolution Diversity of Life copyright cmassengale

Why did you pick the candy you did? What are some reasons you didn’t pick certain candy? What candy “survived” copyright cmassengale

Natural Selection Process by which populations change in response to their environment as individuals better adapted to the environment leave more offspring than those individuals not suited to the environment Adaptations are the changes that occur in a species that results in organisms being better suited to its environment copyright cmassengale

Natural Selection All species have genetic variation. The environment presents many different challenges to an individuals ability to reproduce. Organisms tend to produce more offspring than their enviornment can support copyright cmassengale

Natural Selection Individuals within a population that are better able to cope with the challenges of their environment tend to leave more offspring than those less suited to the environment. The traits of individuals best suited to a particular environment tend to increase in a population over time. copyright cmassengale

Evolution Change in the genetic makeup of a population or species over time Four major points that support the theory of Evolution copyright cmassengale

Theory of Evolution Variation exists within the genes of every population or species (result of random mutation) In particular environment, some individuals of a population or species are better suited to survive (as a result of variation) and have more offspring copyright cmassengale

Evolution Over time, the traits that make certain individuals of a population able to survive and reproduce tend to spread in the population. There is clear proof from fossils and many other sources that living species evolved from organisms that are extinct. copyright cmassengale

Evolution “Nothing in biology makes sense EXCEPT in the light of evolution.” Theodosius Dobzhansky Charles Darwin in later years copyright cmassengale

History of Evolutionary Thought
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Charles Darwin the Naturalist

Voyage of the Beagle Charles Darwin Born Feb. 12, 1809 Joined Crew of HMS Beagle, 1831 Naturalist 5 Year Voyage around world copyright cmassengale

HMS Beagle’s Voyage copyright cmassengale

Evidence for Evolution – The Fossil Record copyright cmassengale

The Galapagos Islands Finches on the islands resembled a mainland finch from South American More types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…) Finches had different types of beaks adapted to their type of food gathering copyright cmassengale

Lamarck’s Theory of Evolution
Jean-Baptiste Lamarck, 1809 One Of First Scientists To Understand That Change Occurs Over Time Stated that Changes Are Adaptations To Environment acquired in an organism’s lifetime Said acquired changes were passed to offspring copyright cmassengale

Idea called Law of Use and Disuse If a body part were used, it got stronger If body part NOT used, it deteriorated copyright cmassengale

Inheritance Of Acquired Traits Traits Acquired During Ones Lifetime Would Be Passed To Offspring copyright cmassengale Clipped ears of dogs could be passed to offspring!

Darwin’s Conclusion Production of more individuals than can be supported by the environment leads to a struggle for existence among individuals Only a fraction of offspring survive each generation Survival of the Fittest copyright cmassengale

The Struggle for Existence
Malthus’ Influence and Key Associations- Darwin’s key association was that individuals that have physical or behavioral traits that better suit their environment are more likely to survive and reproduce than those that do not have such traits. copyright cmassengale

Darwin’s Conclusion Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals Called Natural Selection copyright cmassengale

Publication of “On The Origin of Species”
He Refused To Publish Until He Received An Essay From Alfred Wallace Fellow Naturalist Independently Developed The Same Theory After 25 Years, Someone Else Had Come To The Same Conclusions From Their Observations Of Nature copyright cmassengale

Survival of the Fittest
Key Concept Over Time, Natural Selection Results In Changes In The Inherited Characteristics Of A Population. These Changes Increase A Species Fitness In Its Environment copyright cmassengale

Natural Selection Cannot Be Seen Directly It Can Only Be Observed As Changes In A Population Over Many Successive Generations Radiation Fossil Record copyright cmassengale

Major Problem in Darwin’s Theory
No mechanism to explain natural selection How could favorable variations be transmitted to later generations? With the rediscovery of Mendel’s work in the first half of the 20th century, the missing link in evolutionary theory was found . copyright cmassengale

Opposition to Evolution
The upheaval surrounding evolution began with Darwin’s publication of On the Origin of Species By Means of Natural Selection The debate continues nearly 150 years later copyright cmassengale

Isolation Process by which two populations of the same species cannot breed with one another. Geographically species populations become separated, and change independently over time. At some point they are so different they can no longer breed and are two distinct species. copyright cmassengale

Theory of Evolution Today
Supporting Evidence copyright cmassengale

Evidence of Evolution Key Concept Darwin Argued That Living Things Have Been Evolving On Earth For Millions of Years. Evidence For This Process Could Be Found In: The Fossil Record Homologous Structures of Living Organisms Protein and DNA similarities Similarities In Early Development copyright cmassengale

Fossil Record Provide the most direct evidence that evolution has taken place Fossils In Different Layers of Rock (sedimentary Rock Strata) Showed Evidence Of Gradual Change Over Time copyright cmassengale

Homologous Body Structures
Scientists Noticed Animals With Backbones (Vertebrates) Had Similar Bone Structure Similar structures in different organisms are from a Common ancestor Arms, Wings, Legs, Flippers copyright cmassengale

Homologous Structures copyright cmassengale

Similarities in DNA Sequence

Cytochrome c is a protein that is involved in cellular respiration in all eukaryotic organisms. Human cytochrome c contains 104 amino acids. The following table compares human cytochrome c with cytochrome c from a number of other organisms. Organism Number of cytochrome c amino acids that differ from human cytochrome c amino acids Chickens 18 Chimpanzees Dogs 13 Rattlesnakes 20 Rhesus Monkey 1 Yeasts 56 copyright cmassengale

Similarities In Early Development
Embryonic Structures Of Different Species Show Significant Similarities Embryo – 3 structures Tail Buds that become limbs Pharyngeal pouches copyright cmassengale

Human Fetus – 5 weeks copyright cmassengale

Chicken Turtle Rat copyright cmassengale

Gradualism vs punctuated equilibrium
Gradualism – gradual change over a long period of time lead to species formation Punctuated equilibrium- periods of rapid change in species are separated by periods of little or no change copyright cmassengale

Industrial Melanism copyright cmassengale

Industrial melanism Hypothesis- dark peppered moths are camouflaged on the soot-darkened bark and so are not eaten by the birds. Light moths, on the other hand would stand out against the dark background and would be preyed upon. copyright cmassengale

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