Huygens was writing about the theory of light.
Answer:
Desertification is the destruction of the biological potential of the land and it is generally viewed as an advanced stage of land degradation. human activities also cause the process such as poor irrigation practices, deforestation, the expansion and intensive use of agricultural lands, and overgrazing.
Such human activities put enormous pressure on the land by altering its soil chemistry and hydrology. Modern agriculture causing a negative impact on the soil and land by overexploiting the biological and chemical potential of the land.
I think it’s phenotype bc phenotypes is what the natural selection acts on bc it’s what interacts with an organisms environment and not the genotype.
Answer:
The phrase "disease is an agent of natural selection" means that those individuals which carry specific genes to resist the disease will be selected by the nature, whereas those individuals which that don't have or not capable of developing resistance genes will be excluded.
It is a well-established fact that diseases (mainly outbreaks) are best action of nature to select only those individuals which can modify there genetic material and thrive against the changing environmental conditions. Let's take the example of Coronavirus outbreak (COVID-19) this year. From the statistics we know that old people that develop the disease are most likely killed within a few days. However, young people can develop immunity against the virus easily. Hence, nature selects young people and exclude older people. This natural phenomenon is however driven by the disease.
