In a species, the weight of the newborn ranges from 2 to 5 kg. 97% of the newborn with an average weight between 3 and 3.3 kg survive whereas 99% of the infants born with weights from 2 to 2.5 kg or 4.5 to 5 kg die. Which type of selection process is taking place?

Step-by-step solution

Stabilizing selection (not to be confused with negative or purifying selection) is a type of natural selection in which the population mean stabilizes on a particular non-extreme trait value. Karn & Penrose (1951) showed that birth weight follows a normal distribution, that mortality for newborns is greater for those either under- or over-weight, and that the mean birth weight (7 lbs) coincides with that showing minimum mortality. That is, natural selection reduces the variance in birth weight, in such a way that t