When you drop a ball, it is dropped DOWNWARDS so the number is represented by a negative number. If you toss the ball up it will be a positive number.
To answer your question:
When an object is dropped downwards there will be a negative number since the object is falling downwards.
The process that reduces the number of chromosomes in half is called Meiosis
Unlike natural selection, genetic drift does not depend on an allele’s beneficial or harmful effects. Instead, drift changes allele frequencies purely by chance, as random subsets of individuals (and the gametes of those individuals) are sampled to produce the next generation.
Every population experiences genetic drift, but small populations feel its effects more strongly. Genetic drift does not take into account an allele’s adaptive value to a population, and it may result in loss of a beneficial allele or fixation (rise to 100\%100%100, percent frequency) of a harmful allele in a population.
The founder effect and the bottleneck effect are cases in which a small population is formed from a larger population. These “sampled” populations often do not represent the genetic diversity of the original population, and their small size means they may experience strong drift for generations.
