Among a population of lizards inhabiting an arid habitat, the skin color is controlled by two alleles - B (brown skin color) that is dominant over b (green skin color). The green lizards comprise only 4 percent of the population whereas the brown lizards comprise the rest. Over a long period of time, increased rainfall in the area leads to a transformation of the habitat, with growth of shrubs and small trees. The brown and green lizard numbers almost reverse with the green lizards approaching 81 percent of the total population. Calculate the allele frequency for the green skin color before and after the climate change occurred. Why did the brown lizard, which initially had greater relative fitness than the green lizard, reduce in number drastically?

Question

Among a population of lizards inhabiting an arid habitat, the skin color is controlled by two alleles - B (brown skin color) that is dominant over b (green skin color). The green lizards comprise only 4 percent of the population whereas the brown lizards comprise the rest. Over a long period of time, increased rainfall in the area leads to a transformation of the habitat, with growth of shrubs and small trees. The brown and green lizard numbers almost reverse with the green lizards approaching 81 percent of the total population. Calculate the allele frequency for the green skin color before and after the climate change occurred. Why did the brown lizard, which initially had greater relative fitness than the green lizard, reduce in number drastically?

2, 9; because relative fitness is dependent on environmental conditions

0.2, 0.9; because relative fitness is dependent on environmental conditions

0.2, 0.9; because the green lizard population acquired new adaptations that caused them to increase in number

0.4, 0.81; because the green lizard population acquired new adaptations that caused them to increase in number

Answer 1

The allele frequency for the green skin color before the climate change occurred is 0.2 (4 percent of the population). After the climate change, the allele frequency for the green skin color is 0.81 (81 percent of the population).

The brown lizards reduced in number drastically because the change in the habitat caused a shift in the selective pressures. With the growth of shrubs and small trees, the brown lizard's brown skin color no longer provided them with an advantage in blending with their environment. On the other hand, the green lizards now had a greater advantage in blending with the new vegetation, leading to an increase in their population. This change in selective pressures favored the green lizard population and resulted in the reduction of the brown lizard population.