Question

Evolution: (taken from "Easier Being Green" in National Geographic) The oblong-winged species of katydids was discovered in 1770's. Although the majority of katydids are green, a fraction displays unique bright colors of yellow, orange and hot pink. Entomologists belief the colors are symptoms of erythrism, an anomaly similar to albinism. Although the hot pink color is the dominant trait, these individuals are by far the fewest in number, closely followed by the orange and yellow. The green katydids, even though they carry the recessive allele, are by far the most in number. 1. What microevolution mechanism was the source of the erythrism, which caused the bright color katydids? 2. The variation in color of katydids has been documented for many of years with most individuals displaying the green color and very few with orange, yellow, and hot pink. Which natural selection pressure has been applied to the population over the years - disruptive, stabilizing, directional? 3. Why do you belicve the hot pink is the feer in ber 4. Assume that a small sample of the katydid population is brought to a remote island where electric pink dracaena is the predominant plant species and natural predators of the katydid exist. Which microevolution mechanism initially took place -nonrandom mating, bottleneck, or founder effect? Does the allele frequency of the hot pink allele change in the population? If not, describe why. If it does, describe if it increases or decreases

Answer 1

1) The bright colors of katydids like pink, yellow and orange katydids occurred as a result of a genetic mutation controlled by recessive genes that causes an absence of a normal pigment, such as green, and/or excessive production of another pigment, such as red or pink.

2) It is the example of directional selection.

A directional selection is a force in nature that causes a population to evolve towards one type of trait. In this type of selection, an extreme phenotype is favored over other phenotypes. This results in the shift of the allele frequency over time in the direction of that phenotype.

3) The erythristic mutation is actually a disadvantageous mutation. Hence, most pink or other vividly colored katydids do not survive to adulthood, and this observation explains their rarity or fewer numbers.