Starting from the big tree

Answer 1

If one looked at the evolutionary process from the perspective of the big tree (here, it was assumed to be a representative of plants):

In the long history of biological evolution, plants had gradually developed from a relatively simple form. The early plants may be simple aquatic plants such as algae. As time passed, it gradually developed on land, and mosses, ferns, and so on appeared. For the big trees, they belonged to the higher class of seed plants.

From the perspective of evolutionary mechanisms, in a population, genetic mutations can cause traits to change, which in turn causes genetic variation between individuals. The new traits in the big tree population may be passed down through the population with genes due to species migration or horizontal gene transfer between species. When these genetic variations were affected by non-random natural selection or random genetic drift, and became more common or no longer rare in the population, it meant that the tree population had evolved. For example, large trees might have evolved to adapt to specific soil types, climate conditions, root structures, leaf forms, or reproduction methods. In the process of evolution, the evolution of big trees was also in the direction of adapting to the environment. For example, in an environment where the competition for light was fierce, they might evolve into taller trunks to allow the leaves to obtain more sunlight. In dry areas, they might evolve deeper roots to obtain underground water.

From the perspective of its relationship with other creatures, the tree was also a part of the ecosystem. Its evolution also influenced other creatures such as animals and microorganisms. For example, some animals helped the tree spread seeds, which might have prompted the tree to evolve fruit structures that attracted these animals.