Final answer:
A low frequency of a trait in a population does not necessarily indicate that the trait is recessive. Many factors influence trait frequency, including selective pressures, genetic drift, and gene flow. Recessive traits require two copies of the allele to be phenotypically visible, but dominant traits can also be rare if the alleles are not common.
Step-by-step explanation:
I disagree with the statement that a trait found at a low frequency in a population has to be a recessive trait. While it is true that recessive traits require two copies of the allele to be displayed in an organism's phenotype, the frequency of a trait in a population is influenced by many factors beyond simple dominance. Traits that are recessive can indeed be rare, but so can dominant traits if the alleles that cause them are not common within the gene pool.
Gregor Mendel's classical experiments with peas showed that recessive alleles can disappear in one generation, but they reappear in later generations. This demonstrates that the presence of a trait in a population is not solely dependent on whether the trait is dominant or recessive. Moreover, new research suggests that even traits influenced by a single gene can present a range of phenotypes, and polygenic traits follow even more complex patterns of inheritance that can lead to different frequencies in a population.
In summary, a low frequency of a trait in the population can be due to factors such as selective pressures, genetic drift, mutation rates, and gene flow, among others. It is not necessarily an indication of whether the trait is dominant or recessive.