Natural And Sexual SelectionPresentation Transcript
(November 1997, Pennsylvania) Wayne Roth, 38, of Pittston, was bitten by a cobra belonging to his friend, Roger Croteau, after playfully reaching into the tank and picking up the snake. Wayne subsequently refused to go to a hospital, telling Roger, "I'm a man, I can handle it." Falser words have seldom been spoken. Instead of a hospital, Wayne reported to a bar. He had three drinks, and enjoyed bragging that he had just been bitten by a cobra. Cobra venom is a slow-acting central nervous system toxin. He died within a few hours, in Jenkins Township, Pennsylvania. I'm A Man, I Can Handle It 1997 Darwin Award Nominee Confirmed True by Darwin
Unit: Evolution Lesson: SELECTION Overview : A look at the concept of selection in evolution.
Unit: Evolution Darwin’s concept of natural selection was the keystone to the idea of evolution.
Unit: Evolution Natural Selection: the idea that any favourable trait (a trait that helps an organism be more suited to its environment), would give that organism a better chance of surviving and living long enough to reproduce and pass these traits on to their offspring.
Unit: Evolution This has been seen when examining bacteria. Some bacteria are resistant to antibiotics (a favourable trait for them) and can survive, pass on this resistance to their offspring, and continue to spread.
Unit: Evolution If conditions in an environment change, any members of a species that can survive that change will have an increased opportunity to reproduce and pass that trait on to future generations of that species.
Unit: Evolution A good example of natural selection is the peppered moth. The peppered moth is a white moth with black spots. It lived in pre-Industrial Revolution England on light coloured lichen-covered trees in the 1800’s.
Unit: Evolution When the Industrial Revolution began in England, large amounts of coal were burned, causing a huge increase in the amount of pollution and soot in the air. As a result, the lichen died and the bark of the trees began darkening.
Unit: Evolution A mutant black peppered moth appeared, due to some random mutation. This trait was more favourable considering the changing environment. The black moth was better camouflaged on the dark trees than the lighter peppered moths.
Unit: Evolution The birds that preyed on the peppered moths could find the light coloured moths much easier than the black ones.
Unit: Evolution As a result, the light coloured moth population began to decrease and the dark coloured moth population increased. Within 50 years, 98% of the peppered moth population was dark.
Unit: Evolution This was natural selection at work. Darwin referred to this as Survival of the Fittest . Those organisms that are most fit for a particular environment will have a better chance of surviving and passing on the trait to the next generation.
Unit: Evolution It is interesting to note that with England’s Clear Air laws and cleaner burning fuels, the dark peppered moth population is decreasing and the light population is on the rise.
Unit: Evolution It is important to note that survival of the fittest does not necessarily mean the strongest, fastest, or biggest claws and teeth… just any trait that makes an organism FIT better into its environment.
Unit: Evolution Another form of natural selection is sexual selection . Any trait that makes you more attractive to the opposite sex will increase your chance of passing on your traits to the next generation.
Unit: Evolution Of course, the traits are very specific to each species. Eg. vs
Unit: Evolution The size of antlers or horns in some animals is an indicator used for sexual selection. Obviously, the bigger the antlers, the stronger the animal and the longer it has survived with its good genes!
Unit: Evolution Unfortunately, for the Irish Elk, this became too true…it is believed that it evolved such HUGE antlers, it was no longer able to move through the woods or maybe even hold its neck up. As a result…
Unit: Evolution Some organisms use particular behaviours to signal their sexual potential. Many gazelles do the ole head butting thing…birds sing…fish do a sexy little swim…ostriches do a lovely mating dance…
Unit: Evolution Ostrich Video
Unit: Evolution For thousands of years, humans have used artificial selection or selective breeding to cross particular animals/plants with others to try to maintain or intensify certain traits.
Unit: Evolution Originally, there was one species of dog. Humans then used selective breeding to produce many different forms of dog, but they are still all the same species.
Unit: Evolution For years, humans have selective bred pigs to produce animals with more meat.
Eyes of Bill Nye Video “Evolution: Sexual Selection”
Unit: Evolution The concept of natural selection and survival of the fittest has been stretched to form a new program called the Darwin Awards . These awards go (usually posthumously) to people who have done such stupid things, they have died and removed their genes from gene pool.
Unit: Evolution Assignment: Darwin Award! Find one Darwin Award nominated story you like and print it off… hand it in tomorrow and we will post them on the bulletin board. http://www.darwinawards.com