Because as natural selection occurs and species mate and create offspring this leads to a change in DNA which can lead to new species or evolutionists versions of that species
A descriptive observation may very well be a mixture of both quantitative and qualitative as it can utilize elements of both types. Qualitative deals with the kinds of observations that cannot be measured in numerical form. Quantitative data is just that.
Since the
speed of many physiological processes in marine organisms is determined by the
temperature, the first consequence of the changes in the conditions of the
medium becomes offset the timing of seasonal events, such as the timing of
spawning fish. There have also offset migration routes and spawning areas. So,
as a result of warming in the Sea of Japan, spawning navaga shifted to an
earlier date, because of the reduction of the area of "cold spots"
in the eastern Bering Sea shelf feeding migration of pollock, halibut and crab
are lengthened, but because of the temperature rise to the east of Japan,
spawning saury expanding. These changes significantly affect the success of
reproduction, resulting in changes populations of their fishery.
