Darwins 4 postulates are basic rules for when a trait is likely to .pdf
- 1. Darwin's 4 postulates are basic rules for when a trait is likely to evolve by natural selection. Please apply Darwin's postulates to evolution of antibiotic resistance in a Bacillus bacteria. Why was the lack of understanding of the mechanism of heredity such a significant problem for Darwin? Why was the age of the universe a challenge to Evolutionary thinking in Darwin's time? Why is it not a challenge now? The vertebrate eye is sometimes given as an example of irreducible complexity. How is our emerging understanding of eyes in a variety of animals giving us insight into how simple eyes or partial eyes may have been selectively advantageous in early animals? Solution Answer: darwin's 4 postulates of evolution are: 1. Individual variation (phenotypes amongst individuals vary) 2. In every generation, the proportion of progeny that survives is less than the number of progeny produced. 3. Survival and reproduction of individuals not random. With the current prevailing conditions, individuals with some phenotypes produce more offspring, find more mates, survive better and are naturally selected. 4. Some phenotypic variants passed on to offspring (heritable genetic information is passed on). Thus, more fit phenotypes are better represented in the next generation. therefore, microbacterial resistance of Bacillus tuberculosis is a classic example of darwinian selection. This is not a natural process, but a man-made situation superimposed on nature; there is perhaps no better example of the Darwinian notions of selection and survival. 1. the bacterial populations are individually diverse. 2. the number of bacterial conies surviving is less than the total colonies produced. 3. survival is the result of many years of unremitting selection pressure from human applications of antibiotics, via underuse, overuse, and misuse. 4. the surviving genotypes/traits are transffered to the progeny by conjugation, transfusion and transformation. part 2) Lack of understanding of heredity mechanism was a huge problem for Derwin as he could not give conclusive evidence of natural selection. and may skeptics continued to question his theory like Hugo de Vries, William Bateson till around the 1920s. After which the mechanisms of genetics started coming into fore. part 3) Age of universe was a fierce challenge for the success of theory of evolution
- 2. a) the age of earth then accepted was around 6000 years as estimated by readings of bibl by Bishop Ussher. b) Darwin proposed the age of earth to be several hundred million years so that were sufficient for subtle canges in variation to happen for successful evolution c) William Thompson argues that based on thermodynamics and the source od radiation (which was mainly chemical and gravitational) the age of earth could never be more than 10s of million years which was too less for the theory of evolution to sustain. Hence age of universe was a major sore point for Darwin and his Theory of evolution. Part 4) now it is not a challenge as William thompson has been proved wrong and by 20th century the processes of fission and fusion poering the sun were well establishes and the study of neutrinos fromthe sun had established the age of earth to be approximately 10 billion years. An estimate that makes the theory od evolution test the sways and skeptics of time. Part 5) Irreducibility is a term first coined by Micheal Behe in 1996, and is used in the terms that human eye is too complex to have evolved through evolution. But, this intelligent design did nnot come overnight and has been the outcome of selection pressures like all other organs. E.g: according to Darwin, earlier snails might has develeoped tis light sensitive spot to distinguish from light to dark and they lived longer due to this adaptive mutation, which was then transmitted to generation followed by an indented spot in the Limpet was an advance over the snails as the pigment could now distinguish between the direction of light. . Nautilus has pin hole camera eyes which allows them to see blurry images, which suits them as it could differentiate between a prey or predator and was an advantage. then followed by devlopment of aqueous humor to maintain the shape of eye, to the development of cornea, lens, iris all to get more sharper, clearer images. Hence partial eyes were advantageous to early animals and the human eye is an evolved version of these rudimentary eye like structures.