BIOC51H3 Lecture : Readings 1 notes
11 Aug 2010
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Readings 1
Pgs 73-96
-evidence amassed by Darwin and the early evolutionists indicated that both fossilized and
living organisms were derived with modification from a single common ancestor
-to refine a particular breed of an organism, breeders employ artificial selection in which
individuals are selected with the most desirable traits
-if desirable traits are passed from parents to offspring, then the next generation will have a
higher proportion of the desirable trait than in the last generation
-even though several vegetables are strikingly different in architecture, they all can readily
interbreed due to deriving from wild cabbage
-farmers artificially select in order to yield large crops
-Á]v[Z}Ç}(À}oµ]}vZ}oZvÁ]Zu}](]tion is the logical outcome of
four postulates
-the first postulate is that individuals within populations are variable
-the second postulate is that the variations among individuals are passed from parents to
offspring
-the third postulate is that in every generation, some individuals are more successful at
surviving and reproducing than others
-the fourth postulate is that the survival and reproduction of individuals is not random but
tied to variation
-differential success means that certain traits will be passed on more frequently than others
causing the characteristics of the population to change slightly (Darwinian evolution)
-natural selection happens to individuals while evolution occurs through changing populations
-Darwinian fitness is the ability of an individual to survive and reproduce in its environment
successfully
-adaptation is referred to as a trait or characteristic of an organism that increases its fitness
relative to other individuals without the trait
-each of the four postulates of the Darwin-Wallace theory and their logical consequence can be
verified independently, making them testable
-Á]v[Z}ÇÁ}l]v}v}ooÆ]uv]}vµ]vP}Pv]u(}}µ]}v}
produce a new generation of offspring (snapdragon flowers example)
-finches in the Galapagos Islands reveal relatedness towards each other through similarity in
size and colouration
-the diversity in beaks of the finches shows the diversity of food they eat in the Archipelago
-in one of the Galapagos Islands, finches have variable beak depth sizes proving the first
postulate of variation within populations
-environmental variation can cause beak depth variation through variation in the amount of
food received as chicks as well as injury
-the heritability of a trait is the proportion of variation observed in a population that is due to
variation in genes
-if the difference among individuals is due to allelic differences, then offspring will resemble
parents
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Document Summary
Evidence amassed by darwin and the early evolutionists indicated that both fossilized and living organisms were derived with modification from a single common ancestor. To refine a particular breed of an organism, breeders employ artificial selection in which individuals are selected with the most desirable traits. If desirable traits are passed from parents to offspring, then the next generation will have a higher proportion of the desirable trait than in the last generation. Even though several vegetables are strikingly different in architecture, they all can readily interbreed due to deriving from wild cabbage. Farmers artificially select in order to yield large crops. tion is the logical outcome of four postulates. The first postulate is that individuals within populations are variable. The second postulate is that the variations among individuals are passed from parents to offspring. The third postulate is that in every generation, some individuals are more successful at surviving and reproducing than others.
