1. A species of lizards living in the desert has a mouth only large enough to eat small crickets. For the size phenotype, the cr
icket population will therefore experience: a) disruptive selection
b) directional selection
c) genetic drift
d) stabilizing selection
e) none of the above
Directional selection is a type of natural selection in which an extreme phenotype is favored over other phenotypes. In this case, phenotype of large crickets will be favored, because they cannot be eaten by lizards. Large crickets are advantageous in surviving and reproduction. This will cause the allele frequency to shift over time in the direction of that large size phenotype.
Direction selection is the phenomenon in which a population’s genetic variance changes with respect to environmental changes to select a new phenotype. In this case, the size of cricket, the food source acts as the selection factor for the phenotype, the size of the lizard’s mouth.
In order to accommodate the food source, a single phenotype of mouth size changes and the respective allele is favoured. Correspondingly, the allele frequency will shift unilaterally in one direction only.
The increased frequency of the particular allele ensures a higher survival rate of the lizard. The population evolves towards the favoured phenotype.
The student is likely engaging or forming a hypothesis in which a hypothesis is a scientific method of having to formulate an intelligent or educated guess that may be an answer as to how a problem has occurred in which the student thinks that the racoon may live longer if it only eats vegetables.
