BIOL 142 Lecture Notes - Lecture 18: Allele Frequency, Phylogenetic Tree, Structural Similarity
Thursday, April 26, 2018
BIOL142
•Melanin - specialized protein that can absorb light at different wavelengths#
•Eumelanin - dark skin#
•The older we get, the higher the chances we already reproduced - no natural
selection/pressure between skin color and cancer #
•Vitamin B - sensitive to UV radiation, high exposure decreases folate production
(important for healthy reproduction)#
•Selection pressure in areas close to the equator to maintain dark skin#
•As you move away from the equator, the constraint is relaxed because decreased
UV radiation, less risk to folate levels, dark skin absorbs UV and blocks UVB to enter
the body, vitamin D deficiencies arise#
•Compensation of the lower UV radiation with maximization of the use of it#
•Evolution is one of the five key attributes of life - populations of organisms evolve, or
change through time (adaptation)#
•Lamarck’s theory - Simple organisms originate at the base of the great main by
spontaneous generation#
•Organisms evolve by moving up the chain over time#
•Lamarckian evolution is progressive - always producing “better species”#
•Darwin - Origin of Species#
•Origin of creation:#
•Species are independent (unrelated)#
•Life on Earth is young (approx 6000 years old)#
•Species are immutable (static)#
•Change in species over time - does not follow a linear, progressive pattern#
•The theory of evolution by natural selection proposed a mechanism #
•Darwin described evolution as descent with modification - Modern, modified species
from ancestor species#
•Species are related by common ancestry#
1
