- Slides: 25
+ Theory of Evolution by Natural Selection By Summer Academy Camp Adapted from portalsso. vansd. org/. . . /The%20 Theory%20 of%20 Evolution%2 0 by%20 Natural%20 Sel. . .
+ Cultural Connection -Whole Group Discussion- n What cultural changes have taken place over the past 200 years? 50 years? 10 years? n What changes do you see in the future for the reservation itself? Explain your reasoning for each change. n What change can you personally implement in your own community?
Darwin’s Voyage n Charles Darwin n Set sail on the HMS Beagle in 1831 n Became the ship’s naturalist n Arrived in the Galapagos Islands in 1835 n Observed that the animals on the islands were similar to those on the mainland
Darwin’s Voyage n Galapagos Animals n The Galapagos animals, while similar, were also different from island to island as well as to the mainland n Most obvious difference were the sizes and shapes of the finches’ (small birds) beaks n Sizes and shapes of the beaks were adapted to what the birds ate
Galápagos Finches + n Berry eater Insect eaters Seed Cactus eaters Beak shape varies depending on diet
+ Darwin’s Voyage n On the Origin of Species (Darwin’s book) For the 20 years that followed his return to England Darwin studied plants, animals and adaptations n Darwin wrote about how species can change gradually over many, many generations and become better adapted to new environmental conditions. n
Evolution n The gradual change in a species over time.
Natural Selection Organisms that are better adapted to an environment are more likely to survive and reproduce than organisms that are less well adapted.
+ Adaptations Katydids have camouflage to look like leaves. Non-poisonous king snakes mimic poisonous coral snakes.
Factors that affect Natural Selection: Overproduction most species produce far more offspring than will/can survive Overproducers Producers mature rapidly mature slowly short-lived: most die before they reproduce live long lives: low juvenile mortality rate have many offspring - tend have few offspring at a to overproduce time invest little in individual youngsters care for their young population not regulated population stabilizes near by density: boom and bust carrying capacity population figures
+ Factors that affect Natural Selection: Competition: since food and resources are limited, the offspring have to compete to survive Darwin called it: “Struggle for existence”
+ Factors that affect Natural Selection: Variation: Members within a species exhibit individual differences – these differences must be inheritable Natural selection won’t work in a population of clones! Remember that a key to variation is sexual reproduction.
+ Factors that affect Natural Selection: Fitness : Survival to reproduce/ Only those individuals that are better suited to the environment will survive and reproduce (“Survival of the fittest”). Fitness is when individuals pass on to a portion of their offspring the advantageous characteristics.
+ How do new species form? n Natural Selection n Continental Drift n Changes in environment n Mutations n Man
+ Continental Drift n Fossil records show that when the continents were connected animals walked across. When the continents separated, the animals were separated.
+ Changes in the Environment Example, the pepper moth. Originally, the pepper moth was white, which was good because it could blend in. Then, trains were invented and the soot they produced covered the trees. Making the trees black. The moths that were black could now survive better.
+ Mutations Some species are more susceptible to mutations. Some mutations allow the animal to survive; other mutations do not allow the animal to survive. The mutations that are not decrease the chance of survival remain.
+ Man: Artificial Selection n Selective breeding as practiced by humans on domesticated plants and animals…. n For example: Dogs
+ Evidence of Evolution n Fossil Record n Similarities in Body Structure n Similarities in Early Development n Vestigial Structures n Similarities in DNA
Fossil Record n How fossils form An organism dies and becomes buried in sediment n Minerals gradually replace the bones and more sediments cover the fossil n Pterodactyl Trilobite
Similarities in Homologous Body Structure If the two organisms have body structures that are similar, they must have had a common ancestor.
+ Similarities in Early Development- Embryology n Scientists look at embryos of different organisms and find that many embryos resemble one another.
+ Vestigial Structures n Vestigial Structures A structure found in an organism that is no longer in use but may have been useful at some point in the organism's life. Tail Present in human and all vertebrate embryos. In humans, the tail is reduced; most adults only have three to five tiny tail bones and, occasionally, a trace of a tail-extending muscle. Whales possess a femur and pelvis, but these bones are no longer useful to the mammals.
+ Vestigial Structures Why do dogs have tiny, functionless toes on their feet (dewclaws)? Ancestral dogs had five toes on each foot
+ Similarities in DNA n The more similar the sequences of DNA are, the more closely related the organisms are. n Humans and chimpanzees DNA is more similar than human DNA is to dog DNA.