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11.7 Genetic drift is likely to occur more rapidly on an island, where smaller populations are expected to occur.
- The plants that can best use the resources of the area, including competing with other individuals for those resources, will produce more seeds themselves and those traits that
allowed them to better use the resources will increase in the population of the next generation.
- The Hardy-Weinberg principle of equilibrium states that a population’s allele frequencies are inherently stable. Unless an evolutionary force is acting upon the population, the
population would carry the same genes at the same frequencies generation after generation, and individuals would, as a whole, look essentially the same.
- The theory of natural selection stems from the observation that some individuals in a population survive longer and have more offspring than others, thus passing on more of
their genes to the next generation. For example, a big, powerful male gorilla is much more likely than a smaller, weaker gorilla to become the population’s silverback, the pack’s leader who
mates far more than the other males of the group. The pack leader will, therefore, father more offspring, who share half of his genes, and are thus likely to also grow bigger and stronger
like their father. Over time, the genes for bigger size will increase in frequency in the population, and the population will, as a result, grow larger on average.
- A vestigial structure is an example of a homologous structure that has apparently been reduced through evolution to a non-functional state because its function is no longer
utilized by the species exhibiting it; therefore, any mutations which might reduce its structure are not selected against. The fact that the species has vestiges of the structure rather than
no structure at all is evidence that it was present in an ancestor and evolved to non- functionality through accumulation of random mutations.
- Organisms of one species can arrive to an island together and then disperse throughout the chain, each settling into different niches, exploiting different food resources and,
evolving independently with little gene flow between different islands.
- It is likely the two species would start to reproduce with each other if hybridization is still possible. Depending on the viability of their offspring, they may fuse back into
- In science, a theory is a thoroughly tested and verified set of explanations for a body of observations of nature. It is the strongest form of knowledge in science. In contrast,
a theory in common usage can mean a guess or speculation about something, meaning that the knowledge implied by the theory may be very weak.
- The statement implies that there is a goal to evolution and that the monkey represents greater progress to that goal than the mouse. Both species are likely to be well adapted
to their particular environment, which is the outcome of natural selection.