The very base of the food chain is occupied by plants, which use sunlight directly. These primary producers then become nourishment for the primary consumers, and indirectly for all other organisms, up to the top predators.
The fact that plants are at the base, implies that almost all other living beings depend on them, as well as the course of their evolution.
This is also due to the fact that the generational turnover of plants is extremely long compared to that of the vast majority of animals, and therefore the mutations, and their relative spread in a population is much slower, and it wouldn’t be able to keep up and react to the evolution of the consumers. Indeed, the very opposite is true: it is other animals that generally adapt to plants.
The different varieties of plants become different kinds of food for which different species specialize (like browsing and grazing herbivores).
The amount of plant biomass also regulates the size of the populations of all other organisms: constant rainfall and abundant light, which is what plants need, make the tropics an ecosystem teeming with highly diverse life forms, while at the poles the lack of sunlight supports far fewer herbivores (both in terms of species and population) and even fewer carnivores.
An animal that feeds on grass can afford not to compete with one that feeds on leaves, shrubs or fruit: offering different ways to feed and new shelters, multiplies the available ecological niches that consumers can occupy, and incentivizes them to diversify.
The most important mutations in the history of plant evolution have always heavily influenced the animals that lived at that time:
- The purpose for which fruits evolved is to use the animals that feed on them to spread the seeds more efficiently. Plants have encouraged animals to collaborate by rewarding them with a meal rich in easily digestible sugars, which has also modified their digestive systems (while previously they had to feed on the rest of the plant, which is energetically very expensive to digest) and made available ecological niches that also include that of primates.
- Another crucial point was the evolution of vascular plants, where the presence of cellulose…