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 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 .