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Lecture

Readings 1 notes


Department
Biological Sciences
Course Code
BIOC51H3
Professor
Maydianne Andrade

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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}oZvÁ]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}ooÆ]uv]}vµ]vP}Pv]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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