The following of what? It sounds like there is more than one answer.
The smallest and most exclusive grouping category is species.
From the
books of Geography Seattle is well known for its rain and dark, gloomy skies, but
it may surprise many how pleasant the weather can be, particularly during the
summer months. Using data from meteorological services for the past 50 years,
we can conclude that November through March brings cool temperatures, heavy
cloud cover and rain falling on most days. The coldest month is January with
average lows in the mid to upper 30s F (about 3°C). Weather is pleasant from
April through October, with the best weather in July and August when highs
average in the 70s and rain is uncommon. Skies are mostly clear and smog-free,
though mornings can produce an on-shore flow resulting in low clouds and fog
which typically burns off by mid-day.
The answer is Overproduction
By definition in biological terms, overproduction means that each generation has more offspring that can be supported by its environment and it results to competition for limited resources.
The survival of the fittest's main idea is that the organisms or species that are well adapted to their environment have higher chances of survival.
The descent with modification proposes the idea that species undergo changes over time that produces new species in whcih they share a common ancestor.
Adaptation means organisms learn to adjust to their new environment.