What causes a species to change over time?
what causes some species to not change over time?
what are the causes of species extinctions?

they each offer a fresh glut of resources to the organisms that can arrive and exploit them. as individuals and new species continue to appear, they actively and passively alter the environment. competition for shared resources increases, local abiotic and biotic conditions shift, and the relative abundances of species change accordingly. the process is called ecological succession, and it is one of the earliest and most well-known concepts in ecology.

tissue

explanation:

it is actually formed by geoup of cells which is tissue