- Sep 2022
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bio.libretexts.org bio.libretexts.org
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So in the above scenario, an individual pea plant could be pp (YY), and thus produce yellow peas; pq (Yy), also yellow; or qq (yy), and thus producing green peas (Figure 6.2.16.2.1\PageIndex{1}). In other words, the frequency of pp individuals is simply p2; the frequency of pq individuals is 2pq; and the frequency of qq individuals is q2. And, again, if p and q are the only two possible alleles for a given trait in the population, these genotypes frequencies will sum to one: p2 + 2pq + q2 = 1.
Knowing only the phenotypes of two organisms that reproduce allows us to calculate the predicted offspring using a punnit square, in which a table is made while knowing the genotype frequency and number of individuals allows us to calculate the predicted offspring with the Hardy-Weinberg equilibrium equations. However, these calculations are not 100% accurate, as they are based on the Hardy-Weinberg equilibrium assumptions which is nearly impossible.
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Natural selection and genetic drift usually occur simultaneously in populations and are not isolated events. It is hard to determine which process dominates because it is often nearly impossible to determine the cause of change in allele frequencies at each occurrence. An event that initiates an allele frequency change in an isolated part of the population, which is not typical of the original populatio
Would a natural disaster or another similar event that wipes away a significant part of a population be considered genetic drift or a founder effect?
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bio.libretexts.org bio.libretexts.org
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Other examples of vestigial structures are wings on flightless birds, leaves on some cacti, and hind leg bones in whales.
In the case of these vestigial structures, will populations of flightless birds, for example, eventually lose their wings due to lack of usefulness, or will populations maintain their wings as it is neither a positive nor negative aspect of a flightless bird?
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The webbed feet of platypuses are an adaptation for swimming. The snow leopards’ thick fur is an adaptation for living in the cold. The cheetahs’ fast speed is an adaptation for catching prey.
It is also interesting to note how human populations have adapted over time, first by developing genetic advantages in order to hunt for food (sweating to cool down body and maintain homeostasis) and, more recently, have developed adaptations as technology has become more advanced during the industrial revolution.
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