BIOL 142 Lecture Notes - Lecture 24: Ozone Depletion, Melanocortin 1 Receptor, Folic Acid
Biology 142- Lecture 24- Evolution
Evolution of Skin Color
• UV rays have the most intensity around the equator because UV rays travel a shorter
distance the closer they are to hitting the equator
• UV radiation can damage your DNA
• UV radiation can determinate blood levels of vitamin D
o Folate, commonly known as Vitamin B, and is sensitive to UV radiation
• MC1R gene is important for the production of melanin
o Melanin: a pigment; a specialized protein that absorbs different wavelengths of
light
o eumelanin (darker skin) and pheomelanin (lighter skin)
• The closer we get to the equator, we get higher skin reflectance
o Darker skin absorbs more light
o Lighter skin reflects more like
o As you get closer to the poles people have lighter and lighter skin colors
• Natural selection- eliminating individuals, or making them the best fit for their
environment for when they reproduce
• As you lose ozone layers via ozone depletion, there is less protection against UV
radiation
Evolution by Natural Selection
• Evolution by natural selection is one of the most important ideas in modern biology
• This is one of the best-supported theories in the history of scientific research
• Evolution is one of the five key attributes of life
o Populations of organisms evolve, or change through time; populations adapt
• Lamarck and Evolution as Change through time
o In 1908 Lamark was the first to produce a formal theory of evolution
o Simple organisms originate at the base of the great chain by spontaneous
generation
o Organisms evolve by moving up the chain
• Charles Darwin’s theory: the idea of special creation
o Species are independent (unrelated)
o Life on earth is young
o Species are immutable (unchanging)
o We now know all of these statements are NOT true
• Darwin and Wallace proposed that change in species though time and is also based
on variation
