BIO SCI 100 Lecture Notes - Lecture 3: Alfred Russel Wallace, Second Voyage Of Hms Beagle, Thomas Robert Malthus
4 Oct 2018
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Document Summary
What s a trait: any measurable aspect of an organism: influenced by genes and environment. Distributions of traits vary within and between populations. Traits that enhance survival and reproductive success of individuals. Findings: in dry years, when hard seeds available, beak size increases, when there are many seeds available, smaller beak size increase, dramatic dry year: population drops from 1200 to 200 mostly females survive to the story: moth. Natural selection edits out those individuals with small beaks. Prior to the industrial revolution, dark moths rare in great britain. Experiments allegedly supported thesis that increased predation by birds led to decline of light moths. Problem: no one had actually seen birds eating moths. Along comes bernard kettlewell in 1953: camps in the woods with gin and cigarettes and sets out to prove. Found: black moths twice as likely as white moths to survive than black moths.
