Theroy of Evolution:
GLE 1.1.6 Relationship between organisms
- (Charles) Darwins Theory: 1859
“all life is related and has descended from a common ancestor:”
complex creatures evolve from more simplistic ancestors naturally over time. In a nutshell, as random genetic mutations occur within an organism's genetic code, the beneficial mutations are preserved because they aid survival _
Ex. Darwins Finches and Turtles
- Finches – beaks
- Turtles – Shells based on habitat
-lush vegetation – short neck, dome shaped shell
- dry “cacti” – long neck, saddle back shell
Some Ex. From the Kids?
- Evolution
- Change over time
- Earth or geological Structures Changing over Time
- First assignment!
- Investigate local or world wide Earth, geological changes that are occurring right now!
- Extra Credit. Has there been any geological changes world wide that has been constant over the past ten years. 1. What are they, where are they occurring, and make a hypothesis about the outcome of the possible events that could happen.
- (Jean-Baptiste) Lamarck’s Theory (1809)
- Physical and genetic changes occur in organisms with attributes that are used repetitively or not at all.
-use and disuse Idea (develop useful characteristics or lose not useful)
-inheritance of acquired traits (blacksmith, giraffe, fiddler crab)
Patterns of Diversity
- Why and how come is there diversity among the different species of the world
- How can it be proven that certain species once lived, where there are no organisms of this kind in existence today?
Explanation = Fossil Records
- The differences in the size and shape of the tortoise shells in the galapagose islands. Why were the shells, and physiological shape of the tortoises different from island to island.
Geological Change = James Hutton 1795 (farmer who was known as the founder of “modern geology”
- Credited with Vulcanism – the study of the earths geological creation and
forces of heat beneath the earths surface
- Geological studies along with the fossil record helped to change the minds of the “old school of thought about “creation”
- Geological changes of mountains, landscape and under the sea. Does it happen quickly or does it take a long period of time.
Q’s – If the Earth could change over time, might life change as well?
Tendancy towards perfection – Getting more complex
Use and disuse fiddler crab, giraffe, Hippopotamus
Inheritance of acquired traits
- Thomas Malthus Theory (1798-1826 published 6 editions)
- Highier birth rate to death rate will cause chaos, death and famine.
Populations, Communities and the ability to maintain homeostasis
Population – a group of one species that live in a particular area
Community – All organisms that inhabit a particular area (an assemblage of
populations) living close enough to interact.
***Main Ideas
- Darwin
- Evolution occurs through various individual through internal and external forces.
- Geological, climatatic and through natural selection causes change within a species phenotypic and genotypic makeup.
- Natural Selection
- Survival of the fittest
- Fitness adaptation
- Over time Natural selection causes changes in the available genetics and eventually changes phenotypes.
- Explanations
- Fossil Records
- Geological inferences or clues to the past and changes that have occurred through time.
- Homologous Body Structures
- Structures that have different mature forms, but develop from similar embryonic tissues.
Whales, Cats, Bats and Human arms (mammals)
(not!!!!! bee vs. bat)
- Similarities in early development
Read Darwins Theory!
Start Chapter 16 Early Development : Today
Darwins Theory
He did not understand inheritance and genetics
Mendels work combined with Darwins helped to open the door of understanding
Gene Pools
Mutations
Gene Shufflling
- Single Gene Polygenic traits
- Natural Selection on Single Gene Traits = Can cause a change in the gene frequencies. (Lizards)
Natural Selection on Polygenic Traits =
- Directional Selection = When organisms on one side of the bell curve are more fit for survival.
- Stabilizing Selection = When the individuals at the center of the bell curve for survival are more fit to survive.
- Disruptive Selection = When the population in the middle of the curve become the most hunted or most desired prey, (least likely to survive) this will cause the creation of two new distinct phenotypes.
Genetic Drift
Evolution versus Genetic Equilibrium
Hardy – Weinberg Principle
- The evolutionary process will stop if the Allele Frequencies remains the same. This can happen if the following does not occur in a given population.
Random Mating = random mating must must be possible
Large Population = Genetic drift has less of an effect on large populations.
No Movement Into or out of the Population = Immigration and Emigration
No Mutations = Causes new allele forms and changes gene frequencies.
No Natural Selection = All genotypes in the population must have equal probabilities of survival and reproduction.
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Summary:
Lamarck suggested that adaptation occurred during the lifespan of an organism. So, those giraffes who were able to stretch their necks during their lifetime were better adapted to get food that other giraffes could not. He then suggested that these acquired bodily changes (the slightly longer neck) would be passed on to the next generation through something called "soft inheritance." The notion of "soft inheritance" or passing down of acquired characteristics was a common belief during Lamarck's time.
Darwin believed that changes in physiology occurred randomly. So he would have suggested that some giraffes were born with longer necks because of random genetic mixing, just like some humans are taller than others. He then suggested that the environment made having longer necks an advantage - those giraffes had a better chance at surviving and passing on their longer necks to their offspring.
In each case, the environment is promoting successful adaptations. The main difference is that Lamarck's belief that acquired characteristics could be passed on - so if you worked out at the gym every day and became very muscular, you would have more muscular children. Darwin might agree that your acquired musculature results in you having a better chance of attracting a mate. But he would probably suggest that what might be passed on is a capacity for musculature, not muscles showing up because you passed them on.
Lamarck’s theory primarily differs from Darwin’s theory on the basis that Lamarck’s theory focused more heavily on acquired characteristics. However, the Lamarck theory is also different because it does not account for cellular hereditary information—rather, it does support the transformation of a species through environmental factors, which Darwin’s theory largely does not.